Blisters on the lip include cold sores, sunburn blisters, and canker sores. A person should pay attention to the blister’s location and its appearance to help identify the cause.

There are many reasons why lip blisters develop, including infections, sun damage, and allergies.

This article discusses several possible causes of lip blisters, symptoms, and treatment options.

A blister on the lip could be due to a range of conditions, including:

  • Viral infections: The herpes simplex virus type 1 (HSV-1) is a widespread virus that causes cold sores. Cold sores are painful, fluid-filled sores on the lip that may blister. Cold sores may recur throughout a person’s life.
  • Sunburn: Ultraviolet (UV) rays may cause lip blisters if the sunburn is particularly severe.
  • Blocked or ruptured salivary glands: Mucoceles are fluid-filled cysts that may develop on the inside of the lower lip when the salivary gland ruptures or is blocked.
  • Canker sores:These are common mouth blisters that cause small, round sores on the mouth and lips. Scientists do not know what triggers canker sores, but some research suggests that they develop when the immune system attacks the mouth’s mucosal lining. It is also possible that canker sores develop due to an allergic reaction to ingredients in foods.
  • Trapped keratin: Milia are small keratin cysts that often develop on the face and other areas of the body.
  • Allergic contact dermatitis: Cosmetic or other skin products could irritate the skin and cause inflammation on the face and lips.
  • Syphilis: This is a sexually transmitted infection (STI) that typically causes sores around the genitals, anus, and face.
  • Oral cancer: The likelihood of a lip blister being cancerous is unlikely, but the lining of the mouth may present with patchy pigmentation or white spots, with small ulcers around the mouth and lips that do not heal.

Learn more about all types of mouth sores here.

Other symptoms of lip blisters will vary depending on the cause.

Symptoms of a cold sore may include a burning, itching, or tingling sensation that occurs before the cold sore appears. The sores could ooze pus, which crusts over and forms scabs that last for 5–15 days. They may reappear throughout a person’s life.

A canker sore is a small, round, painful sore that develops on areas of the mouth that move, such as the lips and tongue.

Milia and mucoceles are usually harmless cysts that do not present with any other symptoms. However, if a mucocele is particularly large or is recurring, a doctor may need to remove the salivary gland that is causing the cyst.

Syphilis is an STI that may present with other symptoms, such as fever, tiredness, and muscle aches.

Allergic contact dermatitis may also cause itching and rashes around the face.

Learn about other types of spots on the lip here.

The treatment for lip blisters depends on their cause. Some causes are harmless and require no treatment, such as milia and mild mucoceles. Sunburn blisters will typically heal on their own, but people should take care not to rupture the blister and keep it clean to prevent infection.

However, cosmetic treatments are available to remove cysts on the skin if they are causing concern.

Some options for removing a cyst on the lip include:

  • cryotherapy, which involves freezing the cyst to remove it
  • laser treatment
  • surgery

If a bacterial infection is causing the cyst or blister, a doctor may prescribe antibiotics.

Viral infections, such as cold sores, may clear up on their own without treatment. However, taking over-the-counter (OTC) antiviral medications could help to speed up the healing process.

The best way for a person to prevent allergic reactions is to avoid irritants, where possible. This may involve some trial and error to identify how and when the skin reacts to certain products. For example, lipsticks, skin creams, or washing detergents may contain formulations that aggravate sensitive skin.

Some OTC medication may help alleviate pain or help ease the symptoms of fever. Anti-inflammatory medications can also reduce pain and swelling around the lips.

Learn how to treat infected blisters here.

If a blister or cyst is bothering someone and they want immediate relief, there are some steps they can take at home to alleviate some symptoms.

For sunburn blisters, the American Academy of Dermatology Association (ADA) suggests:

  • using moisturizers with aloe vera
  • drinking plenty of water
  • avoiding popping or touching the blisters
  • using sunblock while it heals

For cold sores, the ADA recommend:

  • using ice packs or sucking ice chips
  • avoiding spicy or acidic foods
  • applying a clean, cold, wet towel on the sores for up to 10 minutes
  • applying petroleum jelly to the sores

A person can use these home remedies for other types of blisters and sores, for example, a canker sore. But, if symptoms persist or worsen, they should speak with a doctor.

Learn about 5 other ways to treat a blister.

Some blisters, such as milia or mild mucoceles cases, are harmless and typically require no medical care. Other conditions, such as sunburn blisters, and cold sores, can be painful but will usually clear up on their own.

A person should talk to a doctor about their symptoms if they are persistent or worsening. If a bacterial infection is causing the blister, or a cold sore is taking more than 2 weeks to heal, a doctor can prescribe antibiotics or antiviral medication. Some people may also wish to see a doctor for cosmetic removal of a cyst.

People with allergies may find talking to a doctor helps them discover what is irritating their lips. A doctor may also request a patch test to see if a substance elicits an allergic reaction on the skin.

Cancer is rarely the cause of lip blisters. However, a person should speak with a doctor if they are experiencing symptoms, such as:

  • ear pain
  • sore throat
  • painful sores in the mouth, lips, and throat
  • red or white patches in the mouth
  • difficulty speaking, eating, or swallowing
  • difficulty moving the jaw or tongue
  • swelling of the jaw and mouth
  • numbness in the mouth and tongue

Learn more about oral cancer here.

A blister on the lip could have many causes, including viral infections, allergies, or trauma. It may occur with other symptoms, such as swelling or fever. The appearance, location, and other symptoms that accompany the lip blister will determine the cause.

Treating blisters on the lip can involve taking antibiotics or antivirals to clear up bacterial and viral infections. If a person is in pain when they eat and drink, OTC painkillers can help reduce discomfort.

Anyone who has a persistent blister that will not heal should talk with a doctor or other healthcare professional.