Migraine Term of the Day - Adverse Reaction

Patient Expert

migraine glossaryWriter's note: Some of you have expressed an interest in learning more of the medical terminology that comes up when discussing migraine disease and other headache disorders. So, I'll be posting a "term of the day," on a regular basis. If there are terms you'd like to have defined, please leave a comment below.

When we're given migraine and headache information, whether from our doctor, a book, or an online article, we sometimes come across medical terms that can be confusing. While it's easy enough to substitute another word or a short phrase for the medical term, there are times when substituting doesn't quite convey the same meaning.

Adverse reaction is one of those terms. We see it used when talking about migraine treatments, new migraine treatments under development, clinical trials, and it's an important word for migraineurs to understand.


An adverse reaction is an undesired side effect caused by a treatment.

Here's an example of how it's used in a sentence:When starting a new treatment, we should be aware of any potential adverse reactions.


We most often see the term side effect, but the more formal term is adverse event. When discussing clinical trials, for example, we're likely to see information about adverse events that occurred during the trial. Adverse reactions can occur immediately or can be delayed and develop over time.

For more terms, see our Migraine Medical Terms Glossary Index.


Webster's Medical Dictionary