Canker sores typically take a couple of weeks to heal, but some home remedies may help reduce pain and irritation.

A canker sore, or aphthous ulcer, is an open and painful mouth ulcer or sore. It’s also the most common type of mouth ulcer.

Some people notice them inside their lips or cheeks. They’re usually white or yellow and surrounded by red, inflamed soft tissue.

Canker sore symptoms include:

  • a small white or yellow oval-shaped ulcer in your mouth
  • a painful red area in your mouth
  • a tingling sensation in your mouth

In some cases, other symptoms may also be present, including:

  • swollen lymph nodes
  • a fever
  • not feeling well

Canker sores aren’t contagious. They usually heal within 1 to 3 weeks without treatment, although the pain normally goes away in 7 to 10 days. Serious canker sores may take up to 6 weeks to heal.

Canker sores usually heal without treatment. However, there are many helpful lifestyle changes you can make to treat canker sores.

For example, you should brush and floss your teeth regularly to prevent a bacterial infection, and avoid spicy foods to speed up the healing process.

Pain can sometimes be severe. You can lessen the discomfort by gargling with mouthwash or salt water. It may feel uncomfortable at first, but it may help reduce pain.

Some ingredients in over-the-counter topical products can help relieve and heal sores, including:

  • benzocaine (Orabase, Zilactin-B, Kank-A)
  • hydrogen peroxide rinses (Peroxyl, Orajel)
  • fluocinonide (Vanos)

Your doctor or dentist may prescribe:

  • an antimicrobial mouth rinse, such as Listerine or mouth rinses with chlorhexidine (Peridex, Periogard)
  • an antibiotic, such as mouthwashes or pills with doxycycline (Monodox, Adoxa, Vibramycin)
  • a corticosteroid ointment, such as hydrocortisone hemisuccinate or beclomethasone
  • a prescription mouthwash, especially one that contains dexamethasone or lidocaine for inflammation and pain

Canker sores can cause several symptoms, which may vary depending on the specific type.

Minor canker sores

Minor canker sores are the most common type of canker sore. Although they can be painful, they generally heal on their own without any scarring around 1 to 2 weeks after onset.

Some of the most common symptoms associated with minor canker sores include:

  • small, oval-shaped bumps inside the mouth
  • a tingling or burning sensation
  • pain when eating, drinking, or speaking

Major canker sores

Major canker sores are less common than minor canker sores and can also cause more severe symptoms. They can take up to 4 weeks to heal and may cause scarring.

Symptoms of major canker sores include:

  • large, round bumps inside the mouth
  • tingling, burning, or inflammation
  • severe pain
  • difficulty eating, drinking, or speaking

Herpetiform canker sores

Herpetiform canker sores are very uncommon. Among people who develop canker sores, only about 5 percent are affected by this type.

In rare cases, they can merge together and form clusters. If this occurs, it could take several weeks to heal and may increase the risk of scarring.

Some possible symptoms of herpetiform canker sores include:

  • small, pinhead-sized bumps inside the mouth, which could form in clusters
  • tingling or burning in the mouth
  • pain, which may be worse when chewing, drinking, or talking

Applying ice or tiny amounts of milk of magnesia to your sores can help relieve pain and promote healing.

Rinsing your mouth with a mixture of warm water and baking soda (1 teaspoon per 1/2 cup of water) can also help with pain and healing.

Honey has been shown to be effective in treating canker sores as well.

Your risk for developing canker sores increases if you have a family history of them. Canker sores have various causes, and the most common ones include:

A deficiency in certain vitamins, such as B3 (niacin), B9 (folic acid), or B12 (cobalamin), can make you more prone to getting canker sores. Zinc, iron, or calcium deficiencies can also trigger or worsen canker sores.

In some cases, the cause of a canker sore can’t be determined.

Cold sores are similar to canker sores. However, unlike canker sores, cold sores can appear outside of your mouth. Cold sores also appear first as blisters, not inflamed sores, and become sores after the blisters pop.

Cold sores are caused by the herpes simplex virus. This virus is carried within your body and can be triggered by stress, exhaustion, and even sunburn. You can also get cold sores on your lips, nose, and your eyes.

Your doctor can usually diagnose a canker sore by examining it. They may order blood tests or take a biopsy of the area if there’s a severe breakout or if they think you might have a:

  • virus
  • vitamin or mineral deficiency
  • hormonal disorder
  • problem with your immune system
  • severe breakout

A cancerous lesion may appear as a canker sore, but it won’t heal without treatment. Some symptoms of oral cancer are similar to those of canker sores, like painful ulcers and swelling in your neck.

But oral cancer is often indicated by unique symptoms, including:

If you experience these symptoms along with canker sore symptoms, see your doctor right away to rule out oral cancer as a cause.

If your canker sore does not resolve in a few weeks, you may experience more serious complications, such as:

  • discomfort or pain while talking, brushing your teeth, or eating
  • fatigue
  • sores spreading outside of your mouth
  • fever
  • cellulitis

See your doctor if your canker sore is causing you unbearable pain or interfering with your life, and if home treatments aren’t working.

Consider doing this even if the complications have developed within just a week or two of the sore developing.

Bacterial infections can spread and create more serious issues, so it’s important to stop a possible bacterial cause of a canker sore quickly.

You can prevent the recurrence of canker sores by avoiding foods that may have previously triggered the outbreak. These often include spicy, salty, or acidic foods. Also, avoid foods that cause allergy symptoms, such as an itchy mouth, a swollen tongue, or hives.

If a canker sore appears due to stress, try out stress reduction methods and calming techniques, such as deep breathing and meditation.

Practice good oral health and use a soft toothbrush to avoid irritating your gums and soft tissue.

Talk with your doctor to determine whether you have any specific vitamin or mineral deficiencies. They can help design a suitable diet plan and prescribe individual supplements if you need them.

Contact your doctor or dentist if you develop:

Seek medical care if you’re unable to eat or drink or your canker sore hasn’t healed within 3 weeks.

Canker sores can be a painful and uncomfortable issue to deal with and may be caused by a variety of factors.

Most canker sores usually heal on their own without any treatment. There are also many home remedies available to soothe symptoms, along with several strategies you can use to prevent them from forming in the first place.

However, be sure to contact your doctor if your canker sore hasn’t healed after a few weeks, or if you develop more severe symptoms or complications.