A swollen tongue can occur for a variety of reasons. One of the common causes is a reaction to a medication. In most cases, tongue enlargement is caused by an adverse reaction to a medication such as an ACE (angiotensin-converting enzyme) inhibitor, which is used to treat high blood pressure, an NSAID, or a nonsteroidal anti-inflammatory drug, such as Aspirin, Ibuprofen, or Naproxen.