Response from Mary E. (Beth) Salcedo, MD:

Antibiotics are among the most widely prescribed drugs in the United States, and they can cause many side effects. But when they are used properly, they’re considered quite safe. Most of their side effects are physical; one of the most common is an allergic reaction.

Anxiety symptoms are one of the lesser-known side effects. In certain people, antibiotics can cause symptoms that may mimic anxiety, such as dizziness or gastrointestinal side effects. In these cases, anxiety may be secondary to other side effects, instead of being a side effect on its own.

Although relatively infrequent, psychiatric symptoms have been reported as a side effect of most antibiotics. The class of antibiotics known as fluoroquinolones (Cipro is a well-known example) are probably most likely to cause anxiety. These side effects can vary among people, and they often get better as an individual adapts to the medication. Fortunately for most people, the symptoms should fully abate once they stop taking the drug.

It is unusual for anxiety to be so distressing that an antibiotic must be discontinued, but this has been reported. Most likely in these cases, however, is the risk factor of a pre-existing anxiety disorder.

Mary E. (Beth) Salcedo, MD, the Medical Director of The Ross Center for Anxiety and Related Disorders in Washington, D.C.