Mouth ulcer (singaw): what helps, what doesn't, and when to see a doctor

Singaw is what most Filipinos call a mouth ulcer. In English it is also called a canker sore or an aphthous ulcer. It is a small, shallow, painful sore on the soft skin inside the mouth.

A typical singaw:

• is round or oval, with a white, yellow or grey center and a red rim
• is usually smaller than 5 millimeters across, though some are bigger
• shows up inside the lips or cheeks, on the tongue (singaw sa dila), on the gums (singaw sa gilagid) or on the floor of the mouth
• hurts more when you eat, drink, talk or brush your teeth

You may have one or a few at a time. Most heal on their own in 1 to 2 weeks. About 1 in 5 people get them again and again.

An ordinary singaw is not contagious, but some infections that cause mouth sores are: see Singaw or something else?

The exact cause is often unknown. Many singaw start with a small injury or irritation:

• biting your cheek, lip or tongue, or brushing too hard
• a sharp tooth, a rough filling, braces or dentures that rub
• burns or scrapes from hot drinks or hard food
• in some people, toothpaste with sodium lauryl sulfate (SLS), a foaming ingredient

Other things make singaw more likely:

• stress and tiredness, such as after many nights of puyat
• hormone changes, such as around your period or during pregnancy
• family history: about 4 in 10 people with mouth ulcers have a relative who gets them
• certain foods in some people, such as chocolate, peanuts or coffee
• low iron, folic acid, vitamin B12, zinc or vitamin D
• some medicines, such as some anti-inflammatory painkillers (NSAIDs)
• quitting smoking: some people get singaw when they first stop. Keep going, because quitting lowers your risk of mouth cancer.

Many ulcers at once, or ulcers that keep coming back, are sometimes linked to another problem, such as celiac or Crohn's disease (which affect the gut) or a weak immune system, for example from HIV. This is uncommon, but it is a reason to get checked.

Other problems also cause sores or patches in the mouth. Some spread to others, and some need different treatment.

• Cold sores (herpes simplex virus) are small blisters on or around the lips, often starting with tingling. They can also be a cluster of tiny sores inside the mouth. They are contagious: don't kiss anyone, especially a baby, until they heal. A child with swollen, painful gums and many mouth sores should see a doctor.
• Hand, foot and mouth disease (HFMD), common in young children, starts with fever and a sore throat. Painful mouth sores and spots or blisters on the hands and feet follow. It spreads easily and usually clears in 7 to 10 days.
• Chickenpox (bulutong) spots can appear inside the mouth too. See our chickenpox guide.
• Measles (tigdas) can cause mouth sores. Deep or widespread sores in a child with measles need a hospital.
• Oral thrush is a yeast infection with white patches or a white coating, often on the tongue. It is common in babies and in people with dentures or diabetes, and needs antifungal treatment.
• Mouth cancer can look like an ordinary ulcer at first, but it does not heal. See When a singaw needs a check-up.

A singaw needs time to heal, and there is no quick fix. These steps ease the pain and help it heal:

• Rinse with warm salt water. Dissolve half a teaspoon of salt in a glass of warm water. Swish it around the sore, then spit it out without swallowing. You can repeat this as often as you like.
• Eat soft, cool foods, such as lugaw, soft rice, mashed kamote or banana, and yogurt.
• Drink cool water, through a straw if drinking hurts.
• Avoid what stings: spicy, very salty or sour food (such as kalamansi, suka or green mango), fruit juice, very hot drinks and crunchy food like chicharon, crackers or toast.
• Keep brushing gently with a soft-bristled toothbrush. If that hurts too much, use a mild, alcohol-free mouthwash instead.
• Leave the sore alone, and get enough rest and sleep.

If a singaw has not healed after 2 weeks, or keeps coming back, have it checked, and always if it lasts more than 3 weeks (see When a singaw needs a check-up).

A pharmacist can suggest something to ease pain or keep the sore clean. If it is for a child, or you are pregnant or breastfeeding, ask a doctor before using any medicine. Tell the pharmacist what other medicines you take, and follow the label or the pharmacist's advice on how to use it.

• Numbing gels, sprays or mouthwashes dull the pain for a while so you can eat, but they don't heal the ulcer.
• Antiseptic (germ-killing) mouthwash helps keep the sore clean. Choose an alcohol-free one, because alcohol stings and irritates the sore.
• Paracetamol or ibuprofen ease pain. Don't take ibuprofen if the sores might be chickenpox, unless a doctor says so. Never give aspirin to anyone under 16.
• Vitamin B12 supplements may help some people heal. Ask a doctor first whether you need one.

From a doctor or dentist. For severe, long-lasting or frequent ulcers, a doctor or dentist may prescribe a steroid paste, spray or mouthwash. Cold sores and thrush may need antiviral or antifungal medicine instead. Never use leftover prescription medicine or someone else's.

If you think a medicine you take every day is causing your singaw, tell your doctor, but don't stop it on your own.

Many families have their own gamot sa singaw. Here is what the evidence says.

"Yakult ang gamot sa singaw." Yakult and similar drinks contain probiotics, which are helpful bacteria. A 2020 review of seven small studies found that some probiotics, mostly given as lozenges, eased singaw pain a little. In most studies they did not make ulcers smaller or less severe, and none tested Yakult. A cool probiotic drink is fine for most people and may feel soothing, but don't count on it to cure a singaw. If you have diabetes, check the sugar on the label. If you have a weak immune system, ask your doctor before taking probiotics.

Tawas (alum). We found no good studies showing that tawas helps, and it can sting an open sore. Don't put it in a child's mouth.

Kalamansi, salt or toothpaste on the sore. Sour and salty things irritate ulcers, and some toothpaste ingredients can trigger them. A warm salt-water rinse is much gentler.

"Galing sa init ng katawan." Health services do not list body heat as a cause of singaw. The usual triggers are small injuries, stress, tiredness, hormones and some foods.

"Kulang sa vitamin C." Health services link singaw to low iron, folic acid, vitamin B12, zinc and vitamin D, not vitamin C. A balanced diet helps; ask a doctor before taking supplements.

Children get ordinary singaw too, often after biting their cheek. Mouth sores with a fever are more often caused by a virus, such as hand, foot and mouth disease or a cold sore virus.

The biggest risk is not drinking enough, because a sore mouth makes children refuse fluids.

• Offer cool water, milk or breast milk often, in small sips, and soft, cool foods like yogurt or lugaw.
• Skip juice and sour, salty or spicy food until the sores heal.
• Watch how much your child pees. Much less than usual can mean dehydration.
• Ask a pharmacist or doctor before giving any medicine or using any mouth gel or spray on a child. Some are not suitable for young children. Never give aspirin to children.
• A white coating on a baby's tongue, or white spots in the mouth, may be thrush. A baby under 4 months with these signs should see a doctor.
• Don't kiss a newborn if you have a cold sore. The cold sore virus is very dangerous to newborn babies. A newborn with blisters or sores around the mouth needs a doctor the same day.
• A baby under 2 months who is not feeding well or has a fever needs a hospital right away.

For a child with fever, see our fever in babies and children guide. The free vaccines at health centers protect against measles.

Most singaw are harmless. See a doctor or dentist if a mouth ulcer:

• lasts more than 3 weeks
• is bigger than usual or looks different from your usual singaw, or is near the back of the throat
• bleeds, or becomes more painful and red, which may mean an infection
• keeps coming back
• comes with fever, weight loss, stomach pain, blood or mucus in your stool, painful or swollen joints, or ulcers on your skin, genitals or around the anus

Why 3 weeks matters. A sore that won't heal is sometimes an early sign of mouth cancer. Most are not cancer, but cancer found early is easier to treat. Also get checked for a red or white patch in the mouth, a lump in the mouth, lip or neck, trouble swallowing or speaking, or a hoarse voice that lasts.

Your risk is higher if you smoke, chew tobacco or nganga (betel nut or betel quid), or drink a lot of alcohol. If so, show any sore that is not healing to a dentist or doctor soon.

A doctor or dentist will look at the sore and ask about your diet, medicines, health and any injury to your mouth. They may take a swab from the sore or do other tests to look for a cause.

• Pharmacy (botika). A good first stop for an ordinary singaw.
• Barangay health station, rural health unit (RHU) or city health center. Start here for a child with fever and mouth sores, or a sore that won't heal. Find one near you.
• Dentist. A dentist can check ulcers, lumps and patches, and fix sharp teeth, fillings or dentures that rub. Find a dentist.
• PhilHealth YAKAP. As of July 2025, check-ups at your registered YAKAP clinic are free, though a private YAKAP clinic may charge up to ₱900 per patient a year. Your YAKAP doctor can also order lab tests. See our PhilHealth YAKAP guide.
• PhilHealth preventive dental care. Under PhilHealth Circular 2024-0034, people registered with a Konsulta provider (the program now called YAKAP) can get a mouth and teeth check, cleaning and fluoride varnish. As of July 2025, your provider refers you to its own dental service or a partner dental clinic. It is free at a public dental clinic; a private one may charge up to ₱1,500 a visit. Ask your YAKAP clinic, and see what PhilHealth covers.

Not sure whether your mouth sore needs a doctor? Ask our symptoms assistant or book a call with a nurse.

You can't always prevent singaw, but these steps lower the chance:

• Brush gently twice a day with a soft toothbrush.
• Get regular dental check-ups, and have a dentist fix sharp teeth, rough fillings, braces or dentures that rub.
• Learn your triggers. If certain foods, stress or a toothpaste seem to bring on singaw, cut back on them, or try a toothpaste without SLS.
• Eat a healthy, balanced diet with vegetables, fruit, and fish, meat, eggs or beans.
• Sleep enough and manage stress.
• Don't smoke or chew nganga, and limit alcohol. This also lowers your risk of mouth cancer.
• Keep your child's vaccines up to date, including against measles.

For most people who get singaw again and again, the ulcers become milder and less frequent over time.