Mouth Ulcers: Why They Recur and When They Need a Doctor

The surge in searches for mouth ulcers this month traces back to a run of short videos, each watched millions of times, making three bold claims: that every canker sore is a vitamin deficiency in disguise, that switching toothpaste ends them for good, and, most alarmingly, that a canker sore is really a form of herpes you can pass to a partner. As of September 2026, none of the major health bodies has changed a word of its guidance in response. The science has not moved; the volume has.

Anyone who has tried to eat a tomato with a crater on the inside of their lip knows why the topic strikes a nerve. A sore the size of a lentil can ruin a week. When they return every month, the questions pile up: why me, why now, is something wrong?

This piece sorts what the evidence supports from what sounds good on camera, grades how strong that evidence is, and spells out the handful of situations where a mouth sore genuinely needs an appointment.

What is a mouth ulcer, and is it the same as a canker sore?

An ulcer is a break in a surface lining that exposes the tissue underneath. In the mouth, that lining is the mucosa, the moist pink membrane coating your cheeks, lips, tongue and the floor of the mouth. When a small patch of it dies and sloughs away, you are left with a shallow crater: round or oval, white, yellow or gray in the center, ringed in red. That is a mouth ulcer. Doctors call the common, non-infectious kind an aphthous ulcer, or recurrent aphthous stomatitis when it keeps returning; stomatitis simply means inflammation of the mouth. In everyday American English it is a canker sore.

Three patterns are recognized. Minor aphthous ulcers account for roughly eight in ten cases: smaller than a centimeter, usually one to five at a time, healing in 7–14 days without a scar. Major aphthous ulcers are larger and deeper, can take several weeks to close, and may leave a scar. Herpetiform ulcers arrive as clusters of dozens of pinpoint sores that can merge into one ragged patch; the name describes the look, not the cause, and they have nothing to do with the herpes virus.

What unites all three is their address. Aphthous ulcers favor the soft, movable linings: the inside of the lips and cheeks, the underside of the tongue, the floor of the mouth. They almost never form on the firm gum hugging the teeth or on the hard palate. That geography is one of the quickest clues a dentist uses to separate a canker sore from a cold sore, which has a very different story.

Are mouth ulcers common?

Very. Population surveys suggest that around one in five people experience recurrent aphthous ulcers at some point, with estimates ranging from about 5% to 25% depending on the group studied and how the question is asked. Almost everyone has had a single ulcer after biting a cheek or scalding the roof of the mouth on pizza. The recurrent pattern, with episodes every few weeks or months, is the one that sends people to search engines.

A few demographic threads run through the data. Ulcers typically begin in childhood or the teenage years; a first-ever episode after age 40 is unusual enough that clinicians look harder for an underlying cause. Women report them slightly more often than men. They cluster in families: if one parent has recurrent ulcers a child’s odds rise, and when both parents are affected the chance climbs further. Non-smokers get them more than smokers, an observation that puzzled researchers for decades and which many ex-smokers discover during their first ulcer-filled months after quitting. The leading explanation is that smoking thickens the mouth’s lining, making it less prone to breaking down. That is not a case for tobacco, which remains the single largest risk factor for mouth cancer.

Frequency also tends to fall with age. Many people plagued by sores as teenagers find them fading to a rare nuisance by their thirties or forties. Nobody fully understands why, though shifts in immune responsiveness and hormone levels are the usual suspects. For a condition this common, the honest summary is that we know a great deal about what it looks like and surprisingly little about exactly why it happens.

Canker sore vs cold sore: what causes fever blisters?

This is the point the viral videos got most wrong, and it matters for a practical reason: one of these is contagious and the other is not.

Fever blisters, also called cold sores, are caused by herpes simplex virus type 1 (HSV-1), a virus most adults worldwide carry after a first exposure in childhood. After that first infection the virus settles into nerve cells near the face and stays for life. Periodically it reactivates, often prompted by sunlight, a cold, fever, stress or hormonal shifts, and travels back along the nerve to the skin. The result follows a script: tingling or burning for a day, then a cluster of small fluid-filled blisters, usually on the border where lip meets skin, which weep, crust and heal in about 7–10 days. During the blister stage the fluid is loaded with virus, so kissing or sharing cups and towels can spread it.

Canker sores differ in almost every respect. They form inside the mouth on soft tissue, not on the lip border. They begin as a sore spot rather than a blister, never crust over, and are not caused by any virus or bacterium that we know of. You cannot catch a canker sore from someone else, and you cannot give one to a partner.

A quick self-check: an ulcer on the inside of the cheek, under the tongue or inside the lip is almost certainly aphthous. Blisters or crusts on the outside of the lip point to HSV-1. When blisters erupt widely inside the mouth, especially in a feverish child with swollen gums, that is a first-time herpes infection and worth a same-week medical visit.

What changed recently

Strictly speaking, the medicine has not moved much; the conversation has. Checked against the current pages from the NHS, the Mayo Clinic and the NIH’s dental research institute, the core guidance for mouth ulcers reads as it did five years ago: most heal within one to two weeks, home care is about comfort, and an ulcer that persists beyond three weeks needs a professional look. None of these bodies has issued a new guideline, and no new prescription treatment has been approved for aphthous ulcers in the United States in that period.

What has shifted is the confidence of online claims. Three ideas drove this season’s spike. First, that recurrent ulcers are always a vitamin B12 deficiency. That rests largely on one randomized placebo-controlled trial published in 2009 with 58 participants, which reported fewer and shorter ulcers in the supplement group over six months. It is a real finding, but a small one never replicated at scale. Second, that sodium lauryl sulfate (SLS), the foaming agent in most toothpaste, is the hidden cause. A handful of small crossover trials dating back to the 1990s produced mixed results, and a 2019 systematic review pooling them judged the evidence low in certainty. Third, that canker sores are a sexually transmitted form of herpes. That one is simply wrong, as the previous section explains.

The most useful document for anyone with stubborn sores remains the 2012 Cochrane review of systemic treatments for recurrent aphthous stomatitis. It examined 25 trials and concluded that no single drug had strong enough evidence to be recommended as first choice. More than a decade later that verdict stands, which is exactly why a thoughtful clinician’s plan still starts with triggers and nutrition rather than a pill.

Why do mouth ulcers keep coming back?

Nobody has found a single cause, and that is the honest starting point. The best-supported model is that recurrent aphthous ulcers happen when a person with an inherited tendency meets a trigger that nudges the immune system into attacking a small patch of the mouth’s lining. Studies of ulcer tissue show T-lymphocytes, the white cells that direct immune attacks, gathering before the surface breaks down. The sore is the end product of a brief, localized, self-directed immune reaction, not an infection.

The triggers people report are mundane. A bite to the cheek, a stray chip edge, a sharp tooth or a new orthodontic wire account for many episodes; the lining is already primed and a minor scrape tips it over. Emotional stress and poor sleep rank next; students notice flares during exams, parents during a newborn’s first months. Hormonal timing is real for a subset of women, with ulcers tracking the days before a period and often easing during pregnancy. Certain foods are frequently blamed: chocolate, coffee, strawberries, eggs, nuts, hard cheese, and anything very spicy or acidic. The evidence for food triggers is mostly diaries and patient reports rather than controlled trials, yet the pattern is consistent enough that a two-month log is worth keeping.

Quitting smoking often brings a temporary surge in ulcers that settles within a few months. Some medicines are associated with aphthous-like sores; if a new sore pattern began within weeks of a new prescription, mention it to the prescriber rather than stopping the drug yourself.

Recurrence, then, is less a mystery than a stack of small, individually modest factors. Remove the sharp tooth and the sleep debt, and many people’s episodes thin out markedly without any medicine at all.

Recurrent mouth ulcers causes: deficiencies and underlying conditions

For a minority of people, especially those whose ulcers are large, frequent, started in adulthood or arrive with other symptoms, the sores are a signpost. This is why a doctor faced with stubborn ulcers will usually order a few blood tests before reaching for anything stronger than a mouthwash.

Nutritional shortfalls come first. Low iron, vitamin B12 or folate is found in a meaningful fraction of people with recurrent ulcers, somewhere between one in ten and one in five in most studies, higher than in the general population. These are correlational findings; correcting a documented deficiency often reduces ulcers, but supplementing when levels are normal has no good evidence behind it. The NIH Office of Dietary Supplements notes that B12 deficiency can present with a sore tongue and mouth ulcers alongside fatigue and tingling in the hands and feet; the cause may be dietary in strict vegans, but is more often reduced absorption with age, stomach conditions or certain long-term medicines.

Gut conditions follow. Celiac disease, in which gluten triggers immune damage to the small intestine, can show up as mouth ulcers years before digestive symptoms, and screening blood tests are widely available and reliable. Crohn’s disease and ulcerative colitis, the two inflammatory bowel diseases, both produce oral ulcers in a subset of patients.

Rarer still are systemic inflammatory conditions. Behçet’s disease, a vasculitis that inflames blood vessels, is defined partly by recurrent mouth ulcers combined with genital ulcers, eye inflammation or skin lesions. Periodic fever syndromes in children, cyclic neutropenia, in which infection-fighting white cells dip every few weeks, and untreated HIV infection complete the textbook list. These are uncommon, but the pattern that should prompt the question is ulcers plus something else: fevers, weight loss, joint pain, eye redness, diarrhea or sores elsewhere on the body.

Does toothpaste cause mouth ulcers?

Sodium lauryl sulfate, SLS for short, is the detergent that makes toothpaste foam. It also strips a little of the mucin layer, the protective film coating the mouth’s lining, which is why some people feel tight and raw after brushing. The hypothesis that this thinning makes ulcers more likely has been around since the early 1990s, when a small Norwegian crossover study reported fewer ulcers during weeks on SLS-free paste.

Later trials were small too, generally 20 to 90 participants, and they did not agree. Some found fewer ulcers, shorter healing or less pain with SLS-free toothpaste; at least one well-designed double-blind crossover found no difference in ulcer count at all. The 2019 systematic review that pooled them concluded that SLS-free toothpaste may reduce the number of ulcers, their duration and pain, while grading the certainty as low because of the trial sizes and inconsistent methods. That is a long way from the headline that SLS is the cause.

A sensible reading goes like this. If you get frequent ulcers, a six- to eight-week switch to an SLS-free paste is a simple, harmless experiment with a plausible mechanism and modest supporting data. Keep an ulcer diary before and during, because recurrent ulcers wax and wane on their own and memory is a poor instrument. If the count clearly drops, stay switched. If nothing changes, SLS was not your problem.

Two cautions. Fluoride is what protects teeth from decay, and most SLS-free pastes still contain it; check the label so the experiment does not trade ulcers for cavities. And no toothpaste, with or without SLS, treats an ulcer that is already present.

How can I treat a mouth ulcer at home?

Most mouth ulcers heal on their own in one to two weeks, so home care is about comfort and about not deepening the crater while it closes. The measures below are the ones mainstream references agree on.

• Protect the spot. Brush with a soft-bristled brush, slow down over the sore, and avoid toothpicks or vigorous flossing at its edge. If a sharp tooth, filling or brace wire sits beside the ulcer, a dentist can smooth or cover it in minutes.
• Change the menu for a week. Chips, crusty bread, citrus, tomato, vinegar and very spicy food all sting an open sore and can tear its edges. Cool, soft and bland works: yogurt, smoothies, scrambled eggs, soup that has cooled a little.
• Rinse. A warm salt-water rinse several times a day is the classic suggestion and is safe for adults and older children who can spit reliably. It will not speed healing dramatically, but it keeps the area clean and many people find it soothing.
• Numb it. Over-the-counter gels, pastes and lozenges containing a local anesthetic or a protective film take the sting out for an hour or so, often enough to get a meal eaten. Follow the packet instructions, and keep products containing benzocaine away from children under two unless a clinician advises otherwise.
• Use a straw if the ulcer sits where liquids pool, and keep fluids up; dehydration slows healing of every tissue, the mouth included.

What does not belong on an ulcer: raw salt, toothpaste, undiluted hydrogen peroxide or hot water. Each causes a chemical or thermal burn to tissue that is already injured.

If pain stops you eating or drinking, or ulcers arrive faster than they heal, that is the moment to stop experimenting and book an appointment; prescription options exist and are described below.

How to heal mouth ulcers fast: what the evidence actually says

Few common conditions show such a gap between confident advice and firm data. Here is the strength of evidence behind the main approaches, in three tiers: randomized trials, observational data, and expert opinion.

Correcting a documented deficiency of iron, B12 or folate: observational data plus small trials. Studies consistently find these deficiencies more often in people with recurrent ulcers, and case series report fewer ulcers after correction. The one randomized B12 trial was small. Verdict: a reasonable first step when a blood test shows a shortfall; unsupported when levels are normal.

SLS-free toothpaste: several small randomized crossover trials, pooled in a 2019 review graded low certainty. Verdict: plausible, harmless to try, far from proven.

Topical corticosteroid preparations prescribed by a clinician: multiple randomized trials and decades of use. They reduce pain and shorten healing of individual ulcers, though they do not prevent the next episode. Verdict: the best-supported prescription option for symptom control; the choice and form belong to the prescriber.

Antiseptic mouthwashes such as chlorhexidine: randomized trials show modest reductions in ulcer duration and discomfort; tooth staining with prolonged use is well documented. Verdict: moderate evidence for short courses.

Systemic tablet treatments for severe disease: the 2012 Cochrane review of 25 trials found none with strong enough evidence to recommend as first-line, and several carry meaningful side effects. Verdict: specialist territory, used case by case.

Salt-water rinses, honey, chamomile, licorice, aloe: traditional use and a scattering of tiny trials. Verdict: anecdote and expert opinion; safe comfort measures, not treatments.

Avoiding trigger foods, managing stress, smoothing sharp teeth: diaries and clinical experience. Verdict: expert opinion, low risk, often rewarding.

The pattern is plain. The strongest evidence supports treating the individual sore and correcting real deficiencies. The weakest supports almost everything sold as prevention.

Mouth sores compared at a glance

When a sore appears, three questions sort most cases: where exactly is it, did it start as a blister, and how long has it been there? The table compares the common culprits.

Type	Cause	Where	Looks like	Typical course	Contagious?
Minor aphthous ulcer (canker sore)	Localized immune reaction; triggers include injury, stress, some foods	Inside lips and cheeks, under tongue, floor of mouth	Round, under 1 cm, white-yellow center, red rim	Heals in 7–14 days, no scar	No
Major aphthous ulcer	Same, more severe	Same sites, plus soft palate and throat	Over 1 cm, deep, irregular	Several weeks; may scar	No
Herpetiform aphthous ulcers	Same; the name describes appearance only	Any soft mouth lining	Dozens of pinpoint sores that may merge	About 2 weeks	No
Cold sore (fever blister)	Herpes simplex virus type 1	Lip border, around nose	Tingling, then clustered blisters, then crust	7–10 days	Yes, especially while blistered
Traumatic ulcer	Bite, sharp tooth, burn, denture rub	Wherever the injury happened	Irregular shape matching the cause	Usually under 2 weeks once the cause is removed	No
Hand, foot and mouth disease	Coxsackievirus and related enteroviruses	Tongue, cheeks, gums, plus palms and soles	Small blisters that become shallow ulcers	7–10 days	Yes
Oral mucositis	Chemotherapy or head-and-neck radiation	Widespread lining	Diffuse redness, then painful raw patches	Follows the treatment cycle	No

Two lines are worth remembering. Location separates canker sores from cold sores more reliably than any other feature: soft inside tissue versus lip border. And duration is the universal red flag. Everything in this list, apart from treatment-related mucositis, should be clearly healing within two to three weeks. A sore that is not, whatever it looks like and however little it hurts, needs an examination. Painless persistence is more concerning than a painful sore that is visibly shrinking.

Common myths about mouth ulcers

Viral claims spread because each holds a grain of something true. Here are the ones circulating now, with the evidence beside them.

“Canker sores are herpes.” No. Cold sores are herpes; canker sores involve no virus and cannot be transmitted. The confusion persists partly because herpetiform ulcers carry a herpes-sounding name, and because both can appear around the mouth during stressful weeks.

“Mouth ulcers mean you are low in B12, so take a supplement.” Partly true, mostly oversold. A minority of people with recurrent ulcers have a measurable deficiency of B12, iron or folate, and correcting it helps them. There is no good evidence that supplementing people with normal levels prevents anything. A blood test, not a video, settles the question.

“Toothpaste is the real cause.” SLS may contribute for some individuals, and switching is a reasonable experiment, but the pooled trial evidence is small and low in certainty. Many people who switch and improve would have improved anyway as their natural cycle waned.

“Rub salt or toothpaste on it to dry it out.” Painful and counterproductive. Concentrated salt or detergent burns tissue that is already raw. A dilute salt-water rinse is the sensible version of this instinct.

“Ulcers mean a weak immune system.” Closer to the opposite. In aphthous ulcers the immune system is overreacting locally, not failing. Truly weakened immunity, as in untreated HIV or during chemotherapy, produces a different pattern: larger, slower-healing, often infected sores.

“Any ulcer that lingers is cancer.” The overwhelming majority of mouth ulcers are harmless, and most mouth cancers occur in people with specific risk factors: tobacco use, heavy alcohol intake, older age and HPV infection. The sensible rule is neither to panic nor to wait: any sore unhealed at three weeks should be examined by a dentist or doctor.

Mouth ulcers in children: what parents should know

Children get mouth ulcers for mostly the same reasons adults do, plus a short list of infections that circulate through daycare and primary school. Sorting them is easier than it sounds.

Recurrent aphthous ulcers often begin between ages 10 and 19, so a child with an occasional single sore inside the lip who is otherwise well is behaving entirely normally. Home care matches the adult version: soft food, cool drinks, gentle brushing, and over-the-counter gels only where the label states they suit the child’s age.

Hand, foot and mouth disease is the most common infectious cause in under-fives. Caused by coxsackieviruses and related enteroviruses, it brings a mild fever, several small blisters that turn into shallow ulcers on the tongue, cheeks and gums, and a spotty rash on the palms, soles and sometimes the buttocks. It usually settles in 7–10 days and is contagious for the first week or so; the main job for parents is keeping fluids going despite the sore mouth.

Herpangina, a cousin caused by the same virus family, puts a few ulcers at the very back of the mouth and throat with a higher fever. Primary herpetic gingivostomatitis is a child’s first encounter with HSV-1: swollen, bleeding gums, many ulcers throughout the mouth, fever and misery lasting up to two weeks. Children who have had it may later develop cold sores on the lip.

The red flag in every childhood mouth infection is the same: dehydration. A child who refuses all fluids, produces fewer than three wet diapers in 24 hours, or is unusually drowsy or floppy needs same-day medical review. So does any baby under three months with mouth sores and a fever, and any child whose ulcers recur monthly alongside fevers or swollen neck glands, since periodic fever syndromes are diagnosed on exactly that pattern.

Mouth sores from cancer treatment and medicines

Not every mouth ulcer is aphthous, and two groups deserve their own paragraph: people undergoing cancer treatment, and people whose sores began after a new medicine.

Oral mucositis is the medical term for inflammation and ulceration of the mouth lining caused by chemotherapy or radiation. Both treatments target rapidly dividing cells, and the mouth’s lining renews itself every one to two weeks, which puts it squarely in the firing line. Nearly everyone receiving radiation to the head and neck develops some degree of mucositis, as does a large share of people on intensive chemotherapy. It typically starts as redness and a burning feeling within the first week or two, progresses to raw, painful patches, and heals as blood counts recover after the cycle ends. Because a sore mouth can mean skipped meals, weight loss and treatment delays, oncology teams have structured protocols: a dental check before treatment, meticulous gentle oral hygiene, bland salt-and-baking-soda rinses, and prescribed pain relief escalated as needed. Anyone in treatment who develops mouth sores should tell the oncology team the same day rather than manage alone, since fever with mucositis can signal infection.

A smaller group of ordinary medicines has been associated with aphthous-like ulcers in case reports and observational series. The list includes some non-steroidal anti-inflammatory painkillers, certain beta-blocker heart medicines, the angina medicine nicorandil, and some drugs that suppress the immune system. The association is real but uncommon, and timing is the clue: sores that appear within weeks of starting something new. The correct response is a conversation with the prescriber, who can weigh alternatives. Stopping a heart or immune medicine on your own because of a mouth sore carries far more risk than the sore does.

When to see a doctor about mouth ulcers

Most ulcers never need a professional, and that is reassuring. The job here is knowing the exceptions. A dentist is often the best first stop, since they examine the mouth lining daily and can smooth a sharp tooth on the spot; a family doctor is the right person when ulcers arrive with symptoms elsewhere in the body.

Book a routine appointment if:

• An ulcer has not clearly started healing after three weeks. This is the single most important rule on this page. A mouth ulcer that won’t heal is usually benign, but persistence is also how oral cancer most often announces itself, particularly in people who smoke or drink heavily, and early examination makes an enormous difference.
• Ulcers recur so often that you rarely have a sore-free week, or they have become larger and deeper than before.
• Ulcers began for the first time after age 40, or appeared within weeks of starting a new medicine.
• They come with other symptoms: unexplained tiredness, weight loss, diarrhea or blood in stool, joint pain, red or painful eyes, rashes, or sores on the genitals or skin.
• A sore is painless, firm or thickened to the touch, bleeds easily, or sits beside a white or red patch that does not wipe away.
• You notice a lump in the neck, numbness of the mouth or lip, or difficulty swallowing alongside a sore.

Seek same-day care if you or your child cannot swallow fluids, if a high fever accompanies widespread mouth blisters, or if someone on chemotherapy develops mouth sores with any temperature.

What a clinician can do is wider than most people expect: blood tests for iron, B12, folate and celiac disease; a review of current medicines; prescription anti-inflammatory gels, pastes or rinses for painful sores; and, for severe recurrent disease, referral to an oral medicine specialist who manages systemic options. Which of these is right for you is a decision for the examining clinician, made with the mouth, the history and the blood results in front of them.

Frequently asked questions

What is an ulcer, exactly?

An ulcer is a break in a surface lining that exposes the tissue beneath it. In the mouth, the lining is the mucosa, and a mouth ulcer appears as a shallow crater with a white, yellow or gray center and a red rim. The common non-infectious type is called an aphthous ulcer or canker sore; it usually heals within one to two weeks.

What causes fever blisters?

Fever blisters, or cold sores, are caused by herpes simplex virus type 1, which most adults carry after a childhood infection. The virus rests in facial nerves and reactivates with sunlight, illness, fever or stress, producing tingling, then clustered blisters on the lip border that crust and heal in 7–10 days. They are contagious, especially during the blister stage.

Canker sore vs cold sore: how do I tell them apart?

Location is the quickest clue. Canker sores sit inside the mouth on soft tissue such as the inner cheek, inner lip or under the tongue, start as a sore spot and never crust. Cold sores appear on the outer lip border, start as tingling and blisters, then crust over. Only cold sores are caused by a virus and only cold sores can be passed to others.

What are the most common recurrent mouth ulcers causes?

An inherited tendency combined with everyday triggers explains most cases: minor injury from biting or sharp teeth, stress and poor sleep, hormonal changes before a period, certain foods, and stopping smoking. A minority have low iron, vitamin B12 or folate, celiac disease, inflammatory bowel disease or, rarely, Behçet’s disease, which is why persistent recurrence deserves blood tests.

How can I treat a mouth ulcer?

Most heal on their own in one to two weeks, so home care centers on comfort: soft bland foods, avoiding acidic or spicy items, gentle brushing with a soft brush, warm salt-water rinses, and over-the-counter numbing gels used as the label directs. A dentist can smooth a sharp tooth that keeps reopening the sore. Severe or frequent ulcers merit prescription options chosen by a clinician.

How to heal mouth ulcers fast: does anything really speed it up?

Nothing available over the counter dramatically shortens healing, though protective gels and salt-water rinses reduce pain and keep the area clean. The best-supported way to shorten an individual ulcer is a prescription topical anti-inflammatory preparation, which randomized trials show reduces pain and healing time. Removing the cause, such as a rough filling, matters more than any product.

Are mouth ulcers a sign of vitamin deficiency?

Sometimes, but not usually. Studies find low iron, vitamin B12 or folate in roughly one in ten to one in five people with recurrent ulcers, more than in the general population. Correcting a confirmed deficiency often reduces episodes. Taking supplements when blood levels are normal has no good evidence behind it, so testing should come before any supplement decision.

Is a mouth ulcer that won't heal something to worry about?

It is something to have examined, not something to panic about. Most ulcers heal within two weeks; the standard guidance is to see a dentist or doctor if a sore has not clearly improved after three weeks. Persistent sores are usually benign, but duration is also the main early sign of oral cancer, especially in people who use tobacco or drink heavily.

Are mouth ulcers contagious?

Aphthous ulcers, the common canker sores, are not contagious; no virus or bacterium causes them and you cannot pass them by kissing or sharing cutlery. Cold sores on the lip, caused by herpes simplex virus, are contagious. In children, hand, foot and mouth disease and herpangina also spread between contacts, so the cause of the sore determines the answer.

Can stress really cause mouth ulcers?

Stress is one of the most consistently reported triggers, with flares clustering around exams, bereavement and sleep deprivation. The evidence comes mainly from patient diaries and observational studies rather than controlled trials, so the link is plausible but not proven. Stress appears to lower the threshold at which a predisposed person’s immune system reacts against the mouth lining.

References

• NHS: Mouth ulcers
• MedlinePlus Medical Encyclopedia: Mouth ulcers
• Cleveland Clinic: Canker Sores
• NIH National Institute of Dental and Craniofacial Research: Fever Blisters and Canker Sores

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.