Swollen Lips: 6 Common Causes & What to Do

Updated in August 2023

Swollen lips are usually a sign of allergies, and can emerge 2 hours after ingesting a new medication or foods that can trigger allergies (like peanuts, seafood, eggs or soy). 

Swollen lips may also be a sign of another health condition, like herpes, dry or burnt lips, a mucocele or other types of inflammation. You should see a doctor if the swelling persists for over 3 days, however, if you also have difficulty breathing, you should proceed to the emergency room. 

Applying ice directly on the lips can help with inflammation and decrease discomfort, however antihistamines may also be useful in some cases. You should follow treatment as prescribed by your doctor. 

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The most common causes of swollen lips include: 

1. Allergies 

A food allergy is the most common reason lips become swollen. It generally occurs about 2 hours after consuming the food allergen. The allergy can also lead to symptoms like coughing, a sensation of a lump in the throat, difficulty breathing and facial redness. Other types of allergies can cause swollen lips, like allergies to make-up medication, dental whitening or plants. 

What to do: Treatment generally involves the use of antihistamines, like cetirizine or loratadine, as prescribed by your doctor. If you have difficulty breathing, you should proceed immediately to the hospital or call an ambulance. 

In addition, you are advised to complete allergy testing to investigate what caused the allergy so that you can prevent a reaction in the future. If the allergy was caused by make-up or other cosmetic products, you are advised to avoid use of the product again. 

2. Herpes

A herpes infection in the mouth can cause lip swelling, as well as blisters on the lips that feel numb or tingling. Other infections, like thrush, can also cause swollen lips. Lips that are dried or cracked are especially prone to infections, as this can attract microorganisms to the lips and promote growth, leading to further redness, fever and pain. 

What to do: You should see your doctor to evaluate your lips and identify the microorganism causing the infection. Once identified, the doctor can prescribe treatment with ointments or pills. Herpes is typically treated with antivirals, like acyclovir, however pain and discomfort can be treated with anti-inflammatories or analgesics, like ibuprofen or acetaminophen.

3. Dry or burned lips

Lips that are burned by the sun, from food, or from acidic foods (like lemons or pineapple) can leading to swelling. This type of swelling can last for a day or two, and is usually accompanied by other symptoms like pain, burning or discoloration. This can also happen with extreme temperature changes in very hot or cold environments. 

What to do: To decrease swelling, apply a moisturizing cream, coconut butter or vaseline directly to areas of dryness or burned skin on the lips. 

4. Mucocele

A mucocele is a type of cyst that can lead to a small, swollen lump on the lips. It usually occurs after biting the lips or after a direct blow, and is usually the result of saliva that has accumulated in an inflamed salivary gland. Learn more about the symptoms of a mucocele and how it is treated. 

What to do: Normally, the mucocele disappears on its own within 1 or 2 weeks without any type of treatment. However, if it continues to grow or lasts for longer, you should see a doctor for assessment. The doctor may opt to drain the cyst to accelerate treatment. 

5. Fall, injury or contusion 

A fall or an accident can cause an injury to mouth, which may lead to swollen lips. Usually, affected areas will become very painful with bruising or red marks. A fall, for example, can even cause the puncture or cut of the lip by the teeth, which is very common in small children who are learning to walk or running around. 

What to do: You can apply cold compresses or cold chamomile tea bags directly to your swollen lips, which should help with swelling within minutes. This can be repeated 2 or 3 times per day. 

6. Impetigo

Impetigo can affect the mouth region, and is often characterized by the presence of small, crusted wounds on the lips or close to the nose. Impetigo is a common childhood infection that is easily transmitted between children. It should be assessed by a pediatrician.

What to do: You should see a doctor to confirm a diagnosis. Treatment usually involves the use of an antibiotic ointment, although other measures should also be considered, like avoiding picking at the wounds, keeping the area clean, and maintaining adequate overall hygiene. 

Other causes

In addition to the above causes, swollen lips can also occur with: 

  • Insect bites
  • A swollen or infected piercing 
  • Braces
  • Spicy foods
  • Pre-eclampsia during pregnancy
  • Canker sores 
  • Keloids
  • Oral cancer
  • Cardiac, liver or kidney failure 

Given there are so many causes for swollen lips, it is important to seek medical attention, especially if you are unsure why  it has occurred. 

When to see the doctor

You should especially see a doctor if: 

  • Your lips become swollen very suddenly, and you also notice swelling in the throat and tongue. These can lead to difficulty breathing if left untreated. 
  • If the swelling lasts for over 3 days.
  • If you notice other symptoms like fever over 38ºC (or 100.4ºF) or have difficulty swallowing
  • You notice swelling to the entire face or other parts of the body

In these cases, the doctor may need to maintain airway patency to ensure you remain breathing by using medication. However, bloodwork and allergy testing should eventually be ordered to avoid further reactions in the future.