10% off £20 OR 15% off £30


10% off £20 OR 15% off £30


🏷️ 3 for 2OffersOffers Hub3 for 2 Mix & MatchSave up to 1/2 PriceBetter than 1/2 priceShort DatedLast chance to buyFree GiftVitamins & SupplementsVitamins & Supplements HubVitamins & Supplements Shop AllCBDShop all CBDCBD Body BalmCBD SprayCBD CapsulesCBD DropsCBD GummiesCollagen & SilicaHair, Skin & NailsShop all Hair, Skin & NailsHair GrowthFunctional MushroomsVitaminsShop all VitaminsMultivitaminsVitamin AVitamin BVitamin CVitamin DVitamin EVitamin KVitamin DrinksMineralsShop all MineralsMagnesiumIronZincCalciumSeleniumChromiumSupplementsShop all SupplementsFibre SupplementsAcidophilus & Friendly BacteriaPeppermint OilGrapeseed ExtractLecithinCollagen & SilicaOmega & Fish OilsPlant Sourced SupplementsSuperfood SupplementsArnicaApple CiderRaspberry KetonesAloe VeraChondroitin & MSMCo Enzyme Q10Evening Primrose OilGarlicGinkgo BilobaGlucosamineGlucomannanSeaweed, Kelps and Aquaceuticals5 HTPSaw palmettoCharcoalWomen's HealthShop all Women's HealthMenopauseMenstrual SupportUrinary Tract HealthPregnancy & ConceptionMen's HealthShop all Men's HealthProstate HealthChildren's HealthConditionShop all ConditionWater RetentionAllergy & Hay Fever CareAnxiety SupportBone & Muscle HealthMuscle Support & Joint PainBrain & Memory SupportWomen's HealthMen's HealthChildren's HealthPain ReliefCold & Immune SupportFatigueDigestive HealthHair, Skin & NailsHeart & CirculationLiver CareMood SupportSexual HealthSleep & RelaxationStress ReliefVisionHerbal & Licensed RemediesShop all Herbal & Licensed RemediesValerianSt John's WortRescue RemedyAgnus CastusAshwagandhaEchinaceaMilk ThistleDevil's ClawGinseng & GuaranaBlack CohoshHomeopathic & Flower RemediesShop all Homeopathic & Flower RemediesRescue RemedyTissue SaltsFlower RemediesHomeopathic RemediesAt-Home TestsVegan Vitamins & SupplementsShop by offer3 for 2 Mix & MatchShort DatedShop by brandHolland & BarrettVitabioticsSolgarNew NordicWeledaBach Original Flower RemediesBioglanBetterYouNatures AidGrass & Co.Free fromDairy FreeGluten FreeSesame Seed FreeCelery FreeCereal FreeCrustaceans FreeEgg FreeFish FreeKiwi FreeLupin FreeNew inFood & DrinkFood & Drink HubFood & Drink Shop AllComic ReliefEasterVegan FoodHoney, Jams & SpreadsShop all Honey, Jams & SpreadsManuka HoneyHoneyJams & ChutneysNut ButtersSpreadsPateTeas & Hot BeveragesShop all Teas & Hot BeveragesCoffee & Coffee SubstituteMushroom DrinksGreen TeaPeppermint TeaHerbal TeaFruit TeaSlimming TeaSleep & Relaxation TeaDried Fruit, Nuts & SeedsShop all Dried Fruit, Nuts & SeedsNutsDried FruitSeedsMixesSuperfoodsShop all SuperfoodsSuperfood PowdersMaca PowderGoji BerriesBaobabMoringa PowderChia SeedsSnacksShop all SnacksChocolate, Cakes & BiscuitsSavoury SnacksSweet SnacksSnack BarsCrisps & ChipsFlapjacksPopcornFood CupboardShop all Food CupboardHoney, Jams & SpreadsBreakfast CerealsSuperfoodsApple Cider VinegarCondiments & SaucesTinned FoodsRice, Pasta, Pulses & GrainsBreakfast CerealsShop all Breakfast CerealsCereals, Bran & FlakesGranolaMuesliOats & PorridgeBreakfast BarsDrinksShop all DrinksKombuchaNatural Energy DrinksJuicesSoft DrinksWaterAlcohol Free DrinksCookingShop all CookingCooking IngredientsApple Cider VinegarCondiments & SaucesSoya & Meat AlternativeSoup & Ready MealsRice, Pasta, Pulses & GrainsHerbs, Spices & SeasoningGravy & StockHome BakingShop all Home BakingBaking MixesBreadFlourSweeteners & Sugar AlternativesEgg SubstitutesDairy AlternativesShop all Dairy AlternativesOat, Rice & Hemp DrinksSoya DrinksNut DrinksCoconut DrinksNutritionally Complete FoodShop by offer3 for 2 Mix & MatchSave up to 1/2 PriceBetter than 1/2 priceShop by brandHolland & BarrettNaturyaGrenadeHeath & HeatherPukkaMeridianNakdTwiningsManuka DoctorBionaFree fromGluten FreeDairy FreeEgg FreeMustard FreeCelery FreeCrustaceans FreeFish FreeKiwi FreeMollusc FreeWheat FreeNew inSports NutritionSports Nutrition HubSports Nutrition Shop AllProteinShop all ProteinClear ProteinWhey ProteinMass GainersVegan ProteinDiet ProteinCaseinBars, Drinks & SnacksShop all Bars, Drinks & SnacksEnergy BarsEnergy DrinksProtein BarsProtein ShakesProtein SnacksNutritionally Complete FoodMeal Replacement ShakesPre Workout & EnergyShop all Pre Workout & EnergyPre WorkoutAmino Energy DrinksAmino Energy PowdersIntra WorkoutKetoPost WorkoutAmino AcidsShop all Amino AcidsAmino Energy PowdersAmino Energy DrinksBCAAL-LysineGlutamineCarnitineArginineCreatineShop all CreatineCreatine PowderSports SupplementsShop all Sports SupplementsTestosteroneSports CollagenRehydrationShop all RehydrationElectrolytesEnergy GelsVegan Sports NutritionShop all Vegan Sports NutritionVegan ProteinVegan Protein BarsVegan Pre Workout & EnergyVegan Amino AcidsVegan CreatineSports AccessoriesShop all Sports AccessoriesBottles & ShakersFitness EquipmentFitness GoalShop all Fitness GoalRecoveryMuscle & StrengthLean MuscleEnergy & EnduranceDiet & Weight LossShop by offerSave up to 1/2 Price3 for 2 Mix & MatchFree GiftShop by brandOptimum NutritionPE NutritionUSNGrenadePhDApplied NutritionFoodspringSiSHuelYfoodFree fromDairy FreeSugar FreeGluten FreeCelery FreeCereal FreeCrustaceans FreeEgg FreeFish FreeKiwi FreeLupin FreeNew inBeautyBeauty HubNatural Beauty Shop AllAromatherapy & HomeShop all Aromatherapy & HomePure Essential OilsBlended Essential OilsBase & Carrier OilsHolisticSkincareShop all SkincarePremium SkincareFace CareBody CareSun CareTanning & BronzingEye CareLip CareFoot CareHand & Nail CareSkin AilmentsSkin OilsCBD BeautyHair Skin & NailsWashing & BathingShop all Washing & BathingShampoo & ConditionerBathing AccessoriesShower Gel & Body WashDeodorantDentalHand WashSoapBath Soak & OilBody ScrubBath Bombs & SaltsFeminine CareIncontinence SupportHair CareShop all Hair CareShampoo & ConditionerHair ColouringHair MasksHair Oil & SerumHair Spray, Gel & MousseHair AccessoriesMother & BabyShop all Mother & BabyBaby Skincare & ToiletriesMakeupElectrical WellnessSexual WellnessShop by offer3 for 2 Mix & MatchLast chance to buySave up to 1/2 PriceShop by brandDr OrganicFaith in NatureWeledaNaturtintTisserandMiaromaSukinQ+AEthiqueSo EcoFree fromAlcohol FreeParfum FreeParaben FreeSLS FreePalm Oil FreeGluten FreeCelery FreeCereal FreeCrustaceans FreeEgg FreeNew inCBDWeight ManagementWeight Management HubWeight Management Shop AllWeight Management SupportSlimming TabletsFat Burners, Binders & Appetite SuppressantsShop all Fat Burners, Binders & Appetite SuppressantsFat BurnersFat BindersCarb BlockersAppetite SuppressantsShakes & Weight Management ShotsShop all Shakes & Weight Management ShotsMeal Replacement ShakesWeight Management ShotsDiet ProteinDiet Food & DrinkShop all Diet Food & DrinkDiet FoodLow Calorie SnacksLow & No Calorie DrinksExercise SupportShop all Exercise SupportFitness EquipmentMeal Replacement ShakesDiet ProteinProtein BarsShop by offer3 for 2 Mix & MatchSave up to 1/2 PriceFree GiftShop by brandOptimum NutritionGrenadeHolland & BarrettUSNPulsinPhDNew NordicSlimExpertApplied NutritionBoombodFree fromDairy FreeSugar FreeGluten FreeWheat FreeNew inVeganHealth & WellnessShop all Health & WellnessJoints Bones & MusclesGut HealthHair Skin & NailsStress AnxietySleep & RelaxationShop by offer3 for 2 Mix & MatchSave up to 1/2 PriceShort DatedShop by brandHolland & BarrettVitabioticsWeledaDr OrganicSolgarNew NordicNaturtintOptimum NutritionHeath & HeatherBounceFree fromDairy FreeGluten FreeParaben FreeSLS FreeAlcohol FreeParfum FreeCelery FreeCereal FreeCrustaceans FreeEgg FreeNew inShop for your WellnessImmunityGut HealthMenopauseWomen's HealthFood & DietMuscle & Joint PainSleep & RelaxationStress ReliefHealthy HeartEnergyLow Mood & DepressionConcentration & AlertnessEye HealthSexual HealthChildren's HealthLearn about WellnessImmunityGut HealthMenopauseFood & DietJoints, Bones & MusclesSports & FitnessSleep & RelaxationHair Skin & NailsAll articlesHealthFood & nutritionGut healthImmunityJoints, bones & musclesWomen's healthWellnessHair & skinMental wellbeingSeasonalSleep & relaxationSports nutritionRecipesAll recipesGluten freeLow sugarVeganDairy freePodcast
What causes mouth ulcers

What causes mouth ulcers?

23 Nov 2022 • 3 min read

Most of us have experienced the irritation of a mouth ulcer at some point.

Maybe you are prone to ulcers in the mouth and seem to get them all the time – or maybe you’ve just got your first one. They can be pretty painful – but are almost always harmless.

Read on to find out what causes mouth ulcers, and who might be particularly prone to developing them.

What is a mouth ulcer?

Mouth ulcers – also known as aphthous ulcers, or canker sores – are small round lesions which appear white in colour with a faintly inflamed red border.

Mouth ulcers develop on the mucous membranes or soft tissues of the mouth. This includes anywhere on the inside of the cheeks, inner lips, tongue and gums.

Mouth ulcers can be irritating, and are sometimes painful – especially when eating, drinking and brushing the teeth.

Mouth ulcers are not contagious. They usually last around seven to 10 days, usually healing without special treatment. Treatment can help relieve the symptoms and hasten the healing process.1

Are there different types of mouth ulcers?

There are four main types of mouth ulcers.2,3,4

  1. Traumatic ulcer

These mouth ulcers are caused by an injury to the inside of the mouth, gums or tongue.

These injuries can be caused by biting the inside of the cheek, burning your mouth on hot food or drink, or even dental wear such as a brace or retainer.

These ulcers heal by themselves in around 10 – 14 days.

  1. Minor aphthous ulcer

The most common type of mouth ulcer, with around 80% of mouth ulcers falling into this category.

Around 2 – 4 mm in diameter, they can be caused by a variety of factors (see list below) and heal by themselves in around 10 – 14 days.

  1. Major aphthous ulcer

These are a slightly larger mouth ulcer, from 0.5cm to 1cm in diameter. This type can take a little longer to heal – at least 14 days and sometimes taking several weeks.

This type can be more painful than the first two types. They also reoccur frequently.

They can be caused by a variety of factors (see list below).

  1. Herpetiform ulcer

These are a rarer form of mouth ulcer. They occur in clusters of small, pinhead-sized ulcers which appear close together. This can give the illusion of one large granular ulcer which can be very painful.

These heal in around 10 days but are known to reoccur frequently.


  • Mouth ulcers are irritating, sometimes painful circular lesions on the inside on the mouth and tongue
  • They are not contagious and usually go away without treatment
  • There are four main types of mouth ulcer – the most common is a minor aphthous ulcer

What causes ulcers?

Anyone can experience a mouth ulcer at any time, and some people get frequent mouth ulcers. There is not always a clear reason as to why they appear.

Check out these 10 reasons which could be causing mouth ulcers.

What causes mouth ulcers?

  1. Injury

The tissues inside your mouth are sensitive. Something as simple as over-zealous brushing can cause minor damage to the oral mucosa (the wet skin layer lining your mouth).

Other things which cause injury to the mouth, such as accidentally biting the inside of your cheek or tongue or a blow to the jaw, disrupt these delicate tissues and can lead to a traumatic mouth ulcer.

Another common cause of mouth ulcers is food that’s too hot, causing scalding to the mouth or tongue. Food that’s particularly acidic or spicy can also trigger them.

Crisp-lovers should watch out, too, as spiky, sharp foods are also known causes of mouth ulcers due to the micro-injuries they can inflict on the oral mucosa as we crunch them.

  1. Irritation

Wearing dental braces, retainers or false teeth are all common causes of traumatic mouth ulcers especially along the gum line. Speak to your dentist or orthodontist if you experience recurrent mouth ulcers, as they can be a sign your dental device doesn’t fit properly and is rubbing.

Similarly, oral piercing such as to the lip or tongue, can be a risk factor for recurring mouth ulcers due to the jewellery causing irritation to the delicate oral tissues.

Anxious habits such as chewing the inside of your cheek could also be at the root of mouth ulcers in the absence of any clear medical explanation.

  1. Nutrient deficiency

Being short of certain vitamins and minerals can cause issues in and around the mouth.

Low levels of iron (anaemia), and a deficiency of zinc and B vitamins, including vitamin B12 have been linked to mouth ulcers.5

  1. Stress

Stress is a contributory factor in a whole range of ailments and is a leading mouth ulcer cause. A high-stress lifestyle, which can include lack of sleep and no time for relaxation, can trigger an outbreak of mouth ulcers especially if you’re already prone to them.

A 2017 study in Iran on 54 volunteers found that recurrent aphthous stomatitis (RAS) – the scientific name for mouth ulcers which keep coming back – was linked to high levels of both anxiety and depression in sufferers.6

  1. Gut inflammation

Your mouth can mirror what’s going on in your gut. This is why bad breath is often a side effect of gut imbalances and acid reflux. Yes - your gut and mouth are directly linked, and the latest research shows that they share some of the same microbial species.7

Disorders such as Coeliac disease (an intolerance to gluten) and inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease are some of the more serious causes behind mouth ulcers.8

This is because they cause inflammation in your digestive system – of which your mouth is a part. Remember, inflammatory bowel diseases can only be diagnosed by a doctor.

However, these conditions are not usually the cause of mouth ulcers in absence of other symptoms – so don’t worry.

  1. Viral infection

Mouth ulcers aren’t usually caused by an infection. However, if you get multiple mouth ulcers at once and they keep coming back (more than a couple of times a year) it might be classed as recurrent aphthous stomatitis (RAS). In these cases, the mouth ulcer might be a secondary symptom of a viral or bacterial infection.9

Infections which can trigger mouth ulcers include herpes simplex, or the cold sore virus, chickenpox, and hand, foot and mouth disease.10

Mouth ulcers are just one symptom of these infections, and mouth ulcers alone are no cause for alarm. Consult your doctor if you’re unsure.

  1. Medication 

Various drugs have been suggested as possible triggers for mouth ulcers. These include:11,12

  • Nicorandil - drug used to treat heart conditions
  • Beta-blockers
  • Ibuprofen and other anti-inflammatory medicines in the NSAID family
  • Oral nicotine replacement therapy
  • Medicines dissolved in the mouth such as aspirin
  • Cytotoxic drugs which treat conditions such as cancer and rheumatoid arthritis
  • Illegal drugs such as cocaine
  1. Certain foods

For some people, certain foods can be a trigger for mouth ulcers due to an underlying sensitivity to that food. These foods can include spicy foods, coffee, peanuts, almonds, strawberries, cheese, tomatoes and wheat flour.13

  1. Smoking

Smoking or using tobacco products like chewing tobacco and snuff can be triggers for mouth ulcers.

Interestingly, people who stop smoking often report an increase in mouth ulcers during the months after they’ve given up. According to a study, this affects up to 2 in 5 quitters.14

  1. Genetics

It seems that certain people are susceptible to getting mouth ulcers. The answer could be in your genes.

A recent study identified genetic variants associated with mouth ulcers and found 97 genetic variations that make a person more likely to get mouth ulcers.15


  • There are various reasons why people develop mouth ulcers
  • Causes of mouth ulcers include certain foods, a nutrient deficiency, smoking, inflammation, stress and oral trauma
  • A recurrent mouth ulcer might be due to viral infection, genetics or certain medications

How to treat mouth ulcers 

  • Salt rinse

Salt water has mildly antiseptic properties and can help soothe the symptoms and hasten the exit of an irritating mouth ulcer.16

Simply dissolve a teaspoon of salt in warm water and rinse the mouth thoroughly. You can do this several times a day.

  • Protective gel

Over-the-counter oral gels which form a protective layer over the mouth ulcer can be effective in soothing pain. They also prevent further irritation from food and drink.17

These gels can contain active ingredients like salicylic acid to help aid healing. Ask your pharmacist to recommend one that’s best for you.

  • Antiseptic mouthwash

An antimicrobial mouthwash containing chlorhexidine gluconate 2mg/mL (0.2%) can help speed up the healing process.

  • Corticosteroid buccal tablets

These tablets can be placed on the ulcer inside the mouth. They release hydrocortisone as they dissolve, which reduces pain and speeds up healing.18

  • Lidocaine spray

Lidocaine is a local anaesthetic, which is combined with an antiseptic in a spray to treat oral soreness such as that associated with mouth ulcers.

What is the best vitamin for mouth ulcers?

Folic acid – studies have shown that a deficiency in folate (the natural form of folic acid) is commonly seen in patients with frequent mouth ulcers, so get lots of folate-rich foods or take a supplement.19

Vitamin B12 – similarly, B12 deficiency is common among cases of recurring mouth ulcers, so top up your levels or take a supplement.

Iron – people with recurring oral ulcers have been found to have lower levels of iron than people without mouth ulcers. A diet rich in iron, or an iron supplement, can help restore your levels. 20

Zinc - in one study, supplementing with zinc helped prevent recurrence of mouth ulcers in patients over 12 months.21

When should I see a doctor for mouth ulcers?

See your GP or dentist if:22

  • your mouth ulcer lasts more than three weeks
  • your mouth ulcers keep recurring
  • your mouth ulcer is especially painful and red – this could be a sign of a bacterial infection, which may need treatment with antibiotics
The advice in this article is for information only and should not replace medical care. Please check with your GP or healthcare professional before trying any supplements, treatments or remedies. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle.

Last updated: 29 April 2021

  • Visa
  • MasterCard
  • PayPal
  • AmericanExpress
  • ApplePay
  • ClearPay
  • AliPay
  • Instagram
  • Pinterest
  • Facebook
  • Twitter
Copyright © Holland & Barrett Retail Limited, 2023. All rights reserved. hollandandbarrett.com is a trading name of Holland & Barrett Retail Limited,. Registered office: Samuel Ryder House, Barling Way, Nuneaton, Warwickshire CV10 7RH. Registered in England: company no. 2758955. Registered VAT no. 211727395.