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Side Effects of Cyclobenzaprine ER
Cyclobenzaprine ER has been studied thoroughly in clinical trials. In these studies, the side effects that occur in a group of people taking the drug are documented and are then compared to side effects that occur in another group of people 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 cyclobenzaprine ER side effects included:
- Dry mouth -- in up to 14 percent (see Amrix and Dry Mouth)
- Dizziness -- up to 6 percent
- Indigestion or heartburn -- up to 4 percent
- Nausea -- up to 3 percent
- Fatigue -- up to 3 percent
- Constipation -- up to 3 percent
- Drowsiness -- up to 2 percent.
In general, studies suggest that taking cyclobenzaprine ER (an extended-release version of cyclobenzaprine) once daily causes less daytime drowsiness compared to taking regular, short-acting cyclobenzaprine three times daily.
There are other, less-common cyclobenzaprine ER side effects that can occur. These side effects occurred in less than 1 percent of people taking short-acting cyclobenzaprine, and it is likely that they could occur with cyclobenzaprine ER as well. For these side effects, it is difficult to tell whether they are actually caused by cyclobenzaprine or other factors.
These less-common cyclobenzaprine side effects include, but are not limited to:
- Coordination problems
- A spinning sensation (vertigo)
- Shakiness (tremor)
- Insomnia
- A general ill feeling (malaise)
- Flushing or hot flashes
- Loss of appetite
- Diarrhea
- Thirst
- Gas
- Double vision
- Increased sweating
- Loss of taste
- Ringing in the ears (tinnitus).
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD