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Cimetidine Side Effects

Common side effects of cimetidine include such things as headaches, diarrhea, dizziness, and drowsiness. When side effects occur with cimetidine, they tend to be minor; however, there are some cimetidine side effects that you should report to your healthcare provider immediately, such signs of an allergic reaction (such as swelling of the mouth or throat).

 

An Introduction to Cimetidine Side Effects

As with any medicine, there are possible side effects with cimetidine (Tagamet®); however, not everyone who takes this drug will experience side effects. In fact, most people tolerate cimetidine 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.
 
(This article covers many, but not all, of the possible side effects with cimetidine. Your healthcare provider can discuss a more complete list of cimetidine side effects with you.)
 

Common Side Effects of Cimetidine

Cimetidine has been studied thoroughly in clinical trials in which a group of people taking the drug have side effects documented and compared to another group not taking the medicine.
 This way, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine.
 
In these studies, the most common side effects of cimetidine included:
 
  • Breast enlargement in men (gynecomastia) -- in up to 4 percent of people (see Cimetidine and Gynecomastia)
  • Headaches -- up to 3.5 percent
  • Diarrhea -- up to 1 percent
  • Dizziness -- up to 1 percent
  • Drowsiness -- up to 1 percent.
     
(Cimetidine Side Effects Continued: Page 2)
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;