The most common cause of tongue swelling is an allergic reaction to something. The more rapid the swelling, the more serious the allergy.
If it swells up within minutes or less than an hour, it is potentially life-threatening. Head to the nearest hospital emergency department. This can be VERY SERIOUS. Please don't delay. If your tongue has started swelling, and has increased in size rapidly, just get yourself to the Emergency Room.
But an enlarged tongue that has developed over a longer period of time (a day or longer) is less likely to have a serious cause.
The most serious allergic reaction which can cause rapid tongue swelling is called anaphylaxis, or anaphylactic shock.
There are a number of symptoms that point towards a possible anaphylactic reaction. These are so important that I'm going to list them right here. Please read this very carefully. The symptoms of anaphylactic shock may include (but NOT be limited to) :
What allergies can result in anaphylaxis?
Almost any type of allergy can lead to anaphylaxis, if the person is sensitive enough to the thing that causes the allergy. A relatively common one is to Penicillin.
Most people are familiar with food allergies such as peanut allergies. Although these can be serious, it's not very common to get a full-blown anaphylactic reaction from a food allergy. However, a rapidly enlarged tongue can still occur, and be quite frightening.
The danger here is that a swollen tongue may block the airway. The quickest treatment is a small dose of adrenalin - usually by injection.
A rapid tongue swelling from an allergy is most likely to be caused by an allergy to something other than food, such as a particular medicine, or from an insect bite or snake bite.
In fact, allergies to medicines of one sort or another are probably the commonest cause. In dentistry, a surprising number of my patients have an allergy to latex, which means that I have to switch to latex-free gloves.
Sometimes, people with a known severe allergy will carry an adenalin injection around with them. (for example, an "EpiPen"). If they happen to experience the first symptoms of an anaphylactic reaction, they can administer the adrenalin themselves within 10 seconds.
There are also many other causes of tongue swelling or an enlarged tongue. These are generally less rapid to develop.
Tongue swelling can occur with:
There are also other, rarer, causes of tongue swelling. The general rule is always the same; if you notice something in your mouth is different or has changed over the last days or weeks, get it checked by a healthcare professional. Most things are harmless; but the important thing is to catch the serious conditions as early as possible.