Side Effects of Ondansetron

As with any medication, there are potential side effects of ondansetron, including headaches, fatigue, and constipation. Most people tolerate ondansetron well and, in many cases, side effects are minor and may be easily treated by you or your healthcare provider. However, there are some more serious side effects that you should report to your healthcare provider immediately, such as chest pain, an unexplained skin rash, or tremors.

 

Ondansetron Side Effects: An Introduction

As with any medicine, there are possible side effects with ondansetron hydrochloride (Zofran®). However, not everyone who takes this drug will experience side effects. In fact, most people tolerate ondansetron well. When side effects do occur, in most cases they are minor, meaning they require no treatment or are easily treated by you or your healthcare provider.
 
(The ondansetron side effects discussed below are not a complete list of side effects reported with this drug. Your healthcare provider can discuss a more complete list of side effects with you.)
 

Common Ondansetron Side Effects

Ondansetron has been thoroughly studied in clinical trials, with many people having been evaluated. In these studies, side effects occurring in the group of people taking the drug are always documented and are then compared to the side effects that occur in a similar group of people not taking the medicine. Based on these studies, the most common ondansetron side effects include:
 
  • Headache -- occurring in up to 27 percent of people
  • Tiredness (fatigue) or a general ill feeling -- in up to 13 percent
  • Constipation -- in up to 9 percent (see Zofran and Constipation)
  • Low oxygen levels (when used for surgery) -- in up to 9 percent
  • Fever -- in up to 8 percent
  • Diarrhea -- in up to 7 percent
  • Gynecological disorders (problems with the female reproductive system) -- in up to 7 percent
  • Anxiety or agitation -- in up to 6 percent
  • Difficulty emptying the bladder (urinary retention) -- in up to 5 percent
  • Itching -- in up to 5 percent
  • Dizziness -- in up to 5 percent.
     
Ondansetron works by blocking serotonin receptors. Serotonin is a chemical that is also important in depression. However, ondansetron works on different receptors than for depression, which explains why depression is not a side effect of ondansetron.
 
(Click Zofran and Depression for more information about the relationship between ondansetron and depression.)
 
(Side Effects of Ondansetron Continued: Page 2)
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;