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A swollen tongue can be dangerous because it could block your airway.

Tongue swelling (or swelling of the lip or throat) is called angioedema. The most common cause of new or "come-and-go" tongue swelling is an allergy.

Two types of allergy can lead to a swollen tongue:

Angioedema from anaphylaxis

Anaphylaxis is a severe, sometimes life-threatening allergic reaction. It happens within minutes of being exposed to an allergy-causing substance. This reaction is also called anaphylactic shock.

It can be caused by insect stings, food, or medicines. It is caused by the release of "histamine" into your bloodstream and tissues. Histamine is an immune system chemical.

Tongue or throat swelling can happen along with an allergic rash (hives), wheezing, diarrhea, and shock (low blood pressure).

Anaphylaxis may need to be treated with injected epinephrine, antihistamine medicines, corticosteroid medicines, and -- in some cases -- monitoring in a hospital's intensive care unit. If the tongue is so swollen that it is obstructing the airway, a breathing tube may need to be placed temporarily.

Angioedema from other causes

In some forms of angioedema, a body chemical called “bradykinin” causes the tongue swelling. Tongue and mouth swelling is usually the only symptom.

This can be caused by medicines, such as:

• ACE inhibitors (a type of blood pressure drug)
• Calcium channel blockers (heart or blood pressure drugs)
• Estrogen
• Non-steroidal anti-inflammatory pain drugs (NSAIDs, such as ibuprofen)

Angioedema due to drugs is treated by stopping the drug. The swelling usually gets better over a couple days. The treatment is primarily supportive because the treatments used in angioedema from anaphylaxis have limited effectiveness in drug induced tongue swelling. However, in emergent situations, patients are often given a corticosteroid (intravenous methylprednisolone) and an antihistamine. If the tongue is so swollen that it is obstructing the airway, a breathing tube may need to be placed temporarily.

If you have angioedema that was caused by an allergy or drug reaction get a medical alert bracelet. This lets doctors and other medical professionals know about your condition if you can't tell them.