Before Shock Wave Therapy: Blood Thinners, Recent Injections and What to Tell Your Doctor

The appointment letter arrives, and with it a short form. Somewhere between the questions about allergies and emergency contacts sits a line that stops people: “Are you taking blood thinners?” Below it, another: “Have you had a steroid injection in this area?” For a treatment that sounds as gentle as a handheld device pressed against a sore heel or elbow, the questions feel oddly serious.

They are serious, in the way a seatbelt is serious. Preparing for shockwave therapy is less about doing anything to your body and more about telling the right people what is already happening inside it. A clinician who knows about your anticoagulant, your recent cortisone shot or your pacemaker can adjust the plan, pick a safer window, or decide that another option suits you better right now.

This explainer walks through what the treatment does, why those two questions matter more than most, and how to have the conversation so nothing important gets left in the waiting room.

How does shockwave therapy work, in plain language?

Extracorporeal shockwave therapy, usually shortened to ESWT, delivers brief, high-energy pressure pulses through the skin into a painful tendon, ligament or bone surface. “Extracorporeal” simply means the energy is generated outside the body. The pulses are acoustic, so they are sound-based rather than electrical, and nothing is implanted or injected.

Two device designs are in common use. Focused shockwave converges energy to a defined depth, a little like a magnifying glass concentrating sunlight. Radial shockwave spreads a pressure wave outward from the applicator tip, with most of its energy near the surface. Both are described by the NHS as non-invasive treatments where pressure waves pass through the skin to help relieve pain and support healing in a persistently sore area.

The leading explanation for how this helps is mechanical stress. Chronic tendon problems, known as tendinopathy, often involve tissue that has stalled in a disordered state rather than healing properly. The pulses appear to trigger a controlled, short-lived inflammatory response, stimulate new small blood vessels and nudge the tissue back into a repair cycle. There is also evidence of an effect on local nerve endings, which may explain why some people notice less pain before any structural change could plausibly have occurred.

What the evidence does not support is any claim of instant or guaranteed repair. Mayo Clinic describes the treatment as an option for chronic plantar fasciitis that has not responded to more conservative care, and notes that results in studies have been mixed. That honest framing matters, because the way the treatment works, by provoking a biological response, is also the reason your medicines and recent injections come into the conversation.

Why preparing for shockwave therapy starts with a conversation, not a to-do list

People often expect preparation to mean fasting, special clothing or a bag of supplies. Almost none of that applies. You can usually eat normally, drive yourself, and wear whatever lets the clinician reach the painful spot. The real work is informational.

Think of the pre-treatment discussion as calibration. The energy level, the number of pulses, the position of the applicator and even whether treatment goes ahead at all depend on details only you can supply. A clinic that treats hundreds of heels will still not know that you started an anticoagulant after a clot last winter, or that another practitioner injected your shoulder recently, unless you say so.

Three themes dominate that conversation:

• Bleeding risk: anticoagulant or antiplatelet medicines, bleeding disorders and recent surgery at the site.
• Tissue vulnerability: a recent corticosteroid injection, a known partial tendon tear, or skin that is broken or infected.
• Whole-body considerations: pregnancy, an implanted cardiac device near the field, active cancer in or near the area, and conditions affecting sensation such as peripheral neuropathy.

None of these automatically closes the door. Each changes the risk-benefit calculation your team is making on your behalf. A clinician who knows about an antiplatelet medicine may expect more bruising and warn you in advance, or may ask the prescriber whether timing can be adjusted. A clinician who knows about a recent injection may schedule the first session further out.

Preparing for shockwave therapy well also means writing things down beforehand. Medication names as they appear on the label, the approximate month of any injection, and the name of the clinician who gave it are all more useful than “a shot a while ago.”

Shockwave therapy and blood thinners: what your team is actually weighing

“Blood thinner” is everyday shorthand for two different drug families. Anticoagulants, such as warfarin and the direct oral anticoagulants, slow the chemical cascade that forms a clot. Antiplatelet medicines, such as aspirin or clopidogrel, make platelets less sticky so they clump less readily. MedlinePlus explains that these medicines do not literally thin blood; they lengthen the time it takes to clot, which is exactly why they are prescribed after strokes, heart attacks, clots or valve replacements.

Shockwave pulses cause tiny mechanical disruption in the tissue they target. In most people this shows up, if at all, as mild redness, small pinpoint bruises called petechiae, or a tender area that fades within days. When clotting is slowed, that same disruption can produce larger bruises or, rarely, bleeding into a tendon sheath or joint. Many ESWT protocols therefore list anticoagulant use and bleeding disorders as reasons for caution or exclusion, particularly for focused, higher-energy treatment deep in tissue.

Here is the part that cannot be said too plainly: do not stop, skip or reduce an anticoagulant or antiplatelet medicine because a shockwave appointment is coming up. These drugs are usually protecting you from something far more dangerous than a bruise. MedlinePlus warns that stopping them without medical advice can allow clots to form. The decision about whether any adjustment is appropriate belongs to the clinician who prescribed the medicine, often in discussion with the person delivering the treatment.

In practice, the conversation may end in several ways. Treatment may proceed at a lower energy setting with closer monitoring. It may be deferred. A different option may be chosen entirely. What you can control is making sure the question is asked early, ideally when the referral is made, not on the treatment couch.

Shockwave therapy after steroid injection: why the interval matters

Corticosteroid injections, commonly called cortisone shots, deliver a potent anti-inflammatory medicine directly into or around a painful joint or tendon. Mayo Clinic notes they can ease pain for weeks to months, which is why many people arrive at a shockwave appointment having tried one or more first.

The tension between the two treatments comes down to mechanism. Shockwave aims to provoke a healing response that includes a brief inflammatory phase. A corticosteroid suppresses inflammation. Delivering both to the same tissue within a short window may blunt whatever benefit the pulses could offer. More importantly, Mayo Clinic lists tendon weakening or rupture among the possible side effects of corticosteroid injections, especially when they are repeated. Applying mechanical energy to a tendon that has recently been exposed to a steroid is a combination most protocols try to avoid.

For that reason, clinics generally ask about any injection into the treatment area within recent weeks and set a waiting interval before the first session. The exact interval varies between protocols and is a judgment call for the treating team, informed by which tendon is involved, how many injections you have had, and how the tissue looks on examination or ultrasound. Mayo Clinic’s broader guidance that cortisone injections are usually spaced apart, and limited in number per year, reflects the same underlying concern about cumulative tissue effects.

What you should bring to the appointment is specific: the approximate date, the body part, and whether it was a corticosteroid or something else. Platelet-rich plasma, hyaluronic acid and local anesthetic-only injections raise different questions, and your team will want to know which one you had. If you are unsure, ask the clinician who gave the injection for a brief written note. It saves everyone from guessing.

Who is shockwave therapy usually for, who is usually asked to wait, and what the alternatives are

The strongest evidence sits with chronic soft-tissue problems that have outlasted first-line care. Mayo Clinic describes ESWT as an option for plantar fasciitis that has not improved with stretching, footwear changes and activity modification. The NHS lists it as a treatment that may be offered for persistent tennis elbow. Other common targets include calcific shoulder tendinopathy, Achilles and patellar tendinopathy, and greater trochanteric pain around the hip. In each case the key word is persistent: a problem measured in months, not days.

People commonly asked to wait, or offered something else, include those who:

• take anticoagulant or antiplatelet medicines, or have a bleeding disorder, until the prescriber has weighed in;
• had a corticosteroid injection into the same area recently;
• are pregnant, since treatment near the trunk or pelvis is generally avoided;
• have an implanted pacemaker or defibrillator close to the planned field;
• have a tumor, infection, open wound or acute fracture at the site;
• have a known complete or significant partial tendon rupture, which needs a different pathway.

Alternatives are not consolation prizes. Structured loading programs, where a physiotherapist prescribes progressive exercise for the tendon, carry good evidence for many tendinopathies and are often continued alongside shockwave rather than replaced by it. Orthotic insoles and footwear changes are first-line for plantar heel pain. Corticosteroid injection remains an option for some conditions, with the trade-offs described above. For a minority of people with long-standing problems, surgical opinion may be appropriate.

The decision about which path fits you sits with your treating team. A good team will tell you not just whether shockwave is possible, but whether it is the most sensible next step given everything else in your history.

What to tell your doctor before shockwave therapy: the information that changes the plan

The pre-treatment form is a starting point, not a ceiling. Clinicians consistently say the most useful patients are the ones who volunteer context the form did not ask for. Here is what tends to matter.

Medicines, in full. Bring the current list, including over-the-counter products. Anticoagulants and antiplatelets head the list, but non-steroidal anti-inflammatory drugs are relevant too: some protocols ask people to avoid them around treatment because the inflammatory response is thought to be part of how shockwave works, although the evidence for that practice is limited. Oral corticosteroids for other conditions, and any medicine that affects bleeding or healing, also belong in the conversation.

Recent procedures at the site. Any injection, surgery, or imaging-guided procedure in the painful area within recent months, with approximate dates.

Medical conditions. Bleeding disorders, diabetes with reduced sensation, peripheral vascular disease, epilepsy, active cancer, and pregnancy or the possibility of it. Implanted devices anywhere near the treatment field.

The story of the pain itself. How long it has been present, what has already been tried, and whether anything suddenly changed. A tendon that became abruptly worse after a pop or snap raises the question of a tear, which should be assessed before any shockwave is delivered.

Your own priorities. If you are an athlete mid-season, a carer who cannot afford a sore week, or someone anxious about pain during treatment, say so. These shape scheduling and the energy settings chosen.

One final habit helps: ask the clinician to repeat back what they understood. Misheard medication names and misremembered dates are among the most common reasons a plan is wrong, and the simplest to fix.

What are the NHS guidelines for shockwave therapy?

People searching for “NHS guidelines” are usually asking two questions: is this treatment recognized, and is it recommended? The answers are yes, and it depends on the condition.

NHS patient information describes shockwave therapy as a non-invasive treatment in which pressure waves are passed through the skin to the painful area, and lists it among options for persistent tennis elbow and plantar fasciitis when simpler measures have not helped. The NHS also notes that the number of sessions depends on how severe the pain is and how the tissue responds, that treatment may cause some discomfort during the session, and that a local anesthetic is sometimes used. Those statements are deliberately modest. They describe a reasonable option, not a guaranteed one.

In the UK, treatment-specific guidance comes from the national guideline body, which has issued interventional procedures guidance for shockwave in several conditions. The pattern across that guidance is consistent: the safety profile is considered acceptable, the evidence of benefit varies by condition and is in places inconsistent, and clinicians are asked to explain that uncertainty to patients and to record outcomes. Mayo Clinic strikes the same note, calling study results mixed while still listing ESWT as an option for stubborn heel pain.

For someone preparing for treatment, the practical takeaway is this: the guidelines emphasize informed consent as much as technique. You should hear, before you agree, what the realistic range of outcomes looks like for your specific problem, what the alternatives are, and what might go wrong. If a service presents shockwave as certain to work, that is a departure from the guidelines, not an application of them.

Where you are treated, and by whom, is a decision for you and your referring clinician based on your own circumstances.

How long does it take to do shockwave therapy, and what actually happens in the room?

The session itself is brief. You will be positioned so the clinician can reach the painful spot, usually sitting or lying down. They locate the tender point by palpation, sometimes confirmed with ultrasound, and apply a water-based gel so the pulses transmit efficiently into tissue rather than bouncing off air at the skin surface.

The applicator is then held against the skin while a set number of pulses is delivered. Each pulse makes a sharp clicking or tapping sound, and most people describe the sensation as a firm, rhythmic thump that ranges from mildly uncomfortable to genuinely sore, particularly over bone. Energy typically starts low and is increased within what you can tolerate. Communicate freely; the clinician adjusts in real time.

The pulses themselves last a matter of minutes. Including positioning, assessment and discussion, a visit is usually short enough to fit into a lunch break. The NHS describes treatment as a course rather than a single event, with sessions spaced roughly a week apart and the total number depending on severity and response. Your team will give you a planned number up front and review whether to continue partway through.

Immediately afterward, the area may be red, slightly swollen or numb-feeling for a short time. You can usually walk out and resume ordinary activity, though vigorous loading of the treated tendon the same day is generally discouraged. Ice packs and heat are often advised against in the first day because they may interfere with the local response the treatment is trying to provoke; follow your team’s specific instructions.

If you take an antiplatelet or anticoagulant and treatment has been agreed, expect the clinician to inspect the skin more carefully afterward and to ask you to report bruising that spreads or feels tight.

A summary table: medicines, injections and conditions to flag before shockwave therapy

The table below gathers the factors most likely to change your plan into one place. It is a prompt for the conversation, not a substitute for it, and it does not predict what your team will decide.

What to flag	Why it matters	What usually happens next
Anticoagulant or antiplatelet medicine	Slower clotting raises the chance of larger bruising or bleeding into tendon or joint	Prescriber consulted; treatment may proceed at adjusted settings, be deferred, or be replaced. Never stop the medicine yourself
Bleeding disorder	Same mechanism, independent of medicines	Specialist input before any decision
Corticosteroid injection at the site in recent weeks	Steroids weaken tendon tissue and suppress the inflammatory response shockwave relies on	Waiting interval set by the team; first session scheduled after it
Other injections (platelet-rich plasma, hyaluronic acid)	Different tissue effects; timing questions differ	Team reviews what was given and when
Pregnancy or possible pregnancy	Treatment near trunk or pelvis avoided as a precaution	Usually deferred
Pacemaker or defibrillator near the field	Theoretical interference with the device	Cardiology advice or alternative site plan
Infection, open wound, tumor or acute fracture at the site	Mechanical energy could worsen the problem or delay diagnosis	Not treated until resolved or investigated
Reduced sensation (for example diabetic neuropathy)	You may not feel when energy is too high	Lower settings, closer monitoring

Notice how often the right-hand column reads “consulted” or “reviewed” rather than “excluded.” Few of these factors are absolute barriers. They are reasons to slow down and involve the right people, which is the whole point of preparing for shockwave therapy properly.

Is it normal to feel worse after shockwave therapy?

A temporary flare is common and, within limits, expected. The treatment works by irritating stalled tissue into a repair response, and irritation is not painless. Many people report that the treated area aches more than usual for a day or two after a session, that it feels bruised to the touch, or that the first steps in the morning are briefly harder. The NHS notes that treatment can be uncomfortable and may leave soreness afterward.

What a typical post-session flare looks like:

• Dull, bruise-like soreness over the treated spot, worst in the first 24 to 48 hours and settling over the following days.
• Mild redness, slight swelling, or small pinpoint bruises on the skin.
• Temporary numbness or tingling in the immediate area that fades within hours.

What a flare should not look like is a new kind of pain. A sharp, tearing sensation, sudden weakness, an inability to bear weight or lift the arm, or a bruise that keeps growing and feels tense under the skin are different signals. On an anticoagulant or antiplatelet medicine, that last point matters most: report any spreading or tight bruise promptly rather than waiting for the next session.

Feeling worse for a short period does not mean the treatment is failing, and feeling nothing at all does not mean it is working. Benefit, when it comes, tends to arrive gradually over the course of treatment and in the weeks after the final session rather than overnight. Studies of ESWT typically measure outcomes weeks to months later for that reason.

Your team should tell you, before the first session, what pattern of soreness they consider ordinary and how to reach them if yours departs from it. If they have not, ask.

What the following days and weeks usually look like

The first evening is often the loudest. Soreness peaks, the area may look flushed, and people sometimes worry they have made things worse. Most clinics advise gentle normal movement rather than rest, avoidance of heavy loading of the treated tendon that day, and simple pain relief only as agreed with the team. Any medicine question, including over-the-counter options, goes back to your prescriber, especially if you take an anticoagulant.

Over the next several days the flare fades. Many people notice their baseline pain is unchanged at this stage, which is normal. If a loading or stretching program has been prescribed, this is when it resumes; the combination of shockwave and progressive exercise is a common pairing because each addresses a different part of the problem.

Sessions typically follow at about weekly intervals, with the NHS describing a course whose length depends on severity and response. Partway through, your team should reassess. Some improvement by the midpoint is encouraging; no change is a prompt to discuss whether to continue, adjust, or try something else.

After the final session, the biology keeps working. Tendon remodeling is slow, measured in weeks and months rather than days, and trials of ESWT commonly report their main outcomes at a follow-up point weeks after treatment ends. Expect your team to schedule a review in that window rather than immediately.

Through all of this, keep a simple log: pain on a scale you choose, first thing in the morning and after activity, plus any bruising. It turns vague impressions into a trend your clinician can act on, and it makes the mid-course conversation far more useful than memory alone.

What people often get wrong about preparing for shockwave therapy

Myth: “I should stop my blood thinner for a few days so I do not bruise.” This is the most dangerous misconception in the whole topic. Anticoagulant and antiplatelet medicines are prescribed because the alternative is a clot in the heart, brain, lungs or legs. MedlinePlus is explicit that stopping them without medical advice can be harmful. A bruise is recoverable; a stroke may not be. Only the prescribing clinician decides whether any change is appropriate.

Myth: “The cortisone shot I had helped, so having shockwave right after will help even more.” The two treatments pull in opposite biological directions, and recent steroid exposure may weaken the tendon you are about to load with pressure waves. Teams set an interval for good reason.

Myth: “Shockwave is just a fancy massage gun.” Consumer percussion devices vibrate the surface. Clinical shockwave delivers calibrated acoustic pulses designed to reach specific tissue at specific energy, under the supervision of someone trained to recognize when not to use it. The screening questions exist precisely because it is not trivial.

Myth: “If it hurts during treatment, something is wrong.” Discomfort during the session is common and the clinician adjusts energy to what you can tolerate. The signals to worry about are the ones described in the red-flag section, not ordinary treatment soreness.

Myth: “More sessions and more energy are always better.” Guidance frames ESWT as a course with a planned number of sessions and reassessment, not an open-ended escalation. Tissue needs time to respond.

Myth: “It works for everything.” The evidence is strongest for a specific set of chronic tendon and fascia problems and is described by Mayo Clinic as mixed even there. Honest preparation includes honest expectations.

Questions to ask your care team before the first session

Walking in with a short list changes the quality of the appointment. These questions are phrased to invite specific answers rather than reassurance.

• Given my anticoagulant or antiplatelet medicine, have you discussed this treatment with the clinician who prescribes it, and what did they advise?
• I had an injection in this area in about this month. How long do you want to wait before treating it, and why that interval for my tendon?
• Is my problem one where the evidence for shockwave is reasonably good, or is this more of a reasonable try? What do the studies for my condition actually show?
• Which device type will you use, focused or radial, and does that change the risks for me?
• How many sessions are you planning, and at what point will we review whether to continue?
• What soreness pattern do you consider normal afterward, and what would make you want to see me urgently?
• Should I pause any over-the-counter pain relief around treatment, and who should I confirm that with?
• What should I do, or avoid, in the day after each session?
• Will I be continuing a loading or stretching program alongside this, and who is coordinating it?
• If this does not help, what is the next step you would consider?

Two questions deserve a follow-up if the answer is vague. The first is about the medicine conversation: “have you discussed it” should produce a yes or a clear plan to do so, not a shrug. The second is about expectations: a team that cannot describe the realistic range of outcomes for your condition has not finished the informed-consent part of the job.

Write the answers down or ask for them in writing. Preparing for shockwave therapy is, in the end, about making sure the decision is made with everything on the table, by the people responsible for your care.

When to call your doctor: red-flag signs after shockwave therapy

Most people experience nothing more than a few days of bruise-like soreness. A small number develop problems that need prompt assessment, and knowing the difference is part of safe treatment.

Contact your care team the same day if you notice:

• a bruise that keeps spreading, feels tense or hot, or is accompanied by rapidly increasing swelling, particularly if you take an anticoagulant or antiplatelet medicine;
• sudden sharp or tearing pain in the treated tendon, a popping sensation, new weakness, or an inability to bear weight or move the limb normally, which could indicate a tendon tear;
• numbness, tingling or pins and needles that persist beyond a few hours or spread beyond the treated area;
• skin that becomes broken, blistered or shows signs of infection such as increasing redness, warmth, pus or fever.

Seek emergency care immediately, rather than waiting for a callback, if you develop chest pain, sudden breathlessness, coughing up blood, one-sided weakness or facial drooping, difficulty speaking, or a painful swollen calf. These are signs of a possible clot or stroke and are especially urgent for anyone whose anticoagulant has been altered or interrupted for any reason.

Less urgent, but still worth a call within a day or two: soreness that is getting worse rather than better after the first 48 hours, pain that wakes you repeatedly at night, or any reaction that was not described to you as expected.

Do not adjust medicines in response to any of these symptoms without speaking to a clinician. If you are unsure whether something counts, call. Teams would far rather answer an unnecessary question than hear about a missed one at the next session. The decision about whether to continue treatment after any complication rests with them.

Frequently asked questions

How does shockwave therapy work on a tendon?

It delivers brief acoustic pressure pulses through the skin into tissue that has stalled in a chronic, disordered state. The mechanical stress appears to trigger a short-lived inflammatory response, encourage new small blood vessels and alter local nerve signaling, nudging the tendon back into a repair cycle. Nothing is injected or implanted. Evidence of benefit varies by condition and is described by Mayo Clinic as mixed.

What are the NHS guidelines for shockwave therapy?

NHS information lists shockwave as a non-invasive option for persistent tennis elbow and plantar fasciitis when simpler measures have not helped, delivered as a course of sessions whose number depends on severity and response. National guidance emphasizes acceptable safety, variable evidence of benefit, and the duty to explain that uncertainty to patients before they consent.

Can I have shockwave therapy and blood thinners at the same time?

Sometimes, but only after your prescriber has been consulted. Anticoagulant and antiplatelet medicines raise the risk of larger bruising or bleeding into tendon or joint, so many protocols treat them as reasons for caution. Treatment may proceed at adjusted settings, be deferred, or be replaced. Never stop or skip the medicine yourself; MedlinePlus warns that doing so can allow dangerous clots to form.

How soon can I have shockwave therapy after steroid injection?

Your treating team sets the interval, and it varies by protocol and tendon. The concern is twofold: Mayo Clinic lists tendon weakening or rupture among corticosteroid injection side effects, and steroids suppress the inflammatory response shockwave is trying to provoke. Bring the approximate date and the type of injection so the team can judge timing accurately.

Is it normal to feel worse after shockwave therapy?

A temporary flare is common. Expect bruise-like soreness over the treated spot, mild redness or small pinpoint bruises, and sometimes brief numbness, usually worst in the first day or two. What is not normal is sharp or tearing pain, sudden weakness, an inability to bear weight, or a bruise that keeps spreading and feels tense, which need a same-day call.

How long does it take to do shockwave therapy?

The pulses themselves last a matter of minutes, and a whole visit including positioning and discussion is short. The NHS describes treatment as a course of sessions, typically spaced about a week apart, with the total number depending on how severe the pain is and how the tissue responds. Your team should tell you the planned number and when they will review progress.

Do I need to stop taking anti-inflammatory painkillers before shockwave therapy?

Some protocols ask people to avoid non-steroidal anti-inflammatory drugs around sessions because inflammation is thought to be part of how the treatment works, though the evidence behind that practice is limited. Do not change any medicine on your own, particularly if you also take an anticoagulant. Ask your treating team and confirm with the clinician who prescribes your medicines.

Who should not have shockwave therapy?

People usually asked to wait or offered an alternative include those on anticoagulants or with bleeding disorders until the prescriber advises, those with a recent corticosteroid injection at the site, pregnant people when the area is near the trunk or pelvis, those with a pacemaker near the field, and anyone with infection, open skin, tumor, acute fracture or a suspected tendon rupture at the site.

What should I bring or tell my doctor at the first shockwave appointment?

Bring your full medication list including over-the-counter products, the approximate dates and types of any injection or procedure at the painful site, and a note of relevant conditions such as bleeding disorders, diabetes with reduced sensation, pregnancy, implanted devices or cancer. Describe how the pain started and whether it changed suddenly, which could signal a tear needing assessment first.

What happens if shockwave therapy does not help?

Your team reassesses rather than simply adding sessions. Alternatives include a structured progressive loading program with a physiotherapist, footwear or orthotic changes for heel pain, corticosteroid injection with its own trade-offs, or, for a minority with long-standing problems, a surgical opinion. The right next step depends on your condition and history and is a decision for you and your treating team.

References

• NHS: Tennis elbow
• NHS: Plantar fasciitis
• MedlinePlus: Blood thinners

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.