Flexeril Side Effects

by on December 20, 2011


Flexeril (Cyclobenzaprine) is a short-term treatment option for patients suffering from muscle pain and spasms. This medication can provide relief from this pain, but does come with a wide range of potential side effects. The most notable side effects of Flexeril include drowsiness and dizziness. To minimize these effects, patients taking this medication should rise slowly when sitting or laying down. Getting up too quickly, especially from sleep, can enhance these Flexeril side effects.  Patients who need to drive, operate machinery, or perform focused work may find that Flexeril does not meet their needs. Those who have a serious injury and the time for rest and recovery, however, can experience relief from their discomfort with this medication.

Common Flexeril Side Effects

Common side effects of Flexeril include the following:

  • Nausea
  • Stomach pain
  • Diarrhea
  • Constipation
  • Drowsiness
  • Dizziness
  • Nervousness
  • Fatigue
  • Dry mouth


These side effects are generally mild. Many will fade away as your body adjusts to the medication.  Drowsiness is the most common side effect of Flexeril with up to 39 percent of patients on this medication experiencing it.

Dry mouth and dizziness are the second and third most common side effects, occurring in 32 and 11 percent of users, respectively. However, if these side effects are severe or persistent, you may need to consult your doctor to discuss treating the side effects or switching to a different muscle relaxer.

Serious Flexeril Side Effects

Allergic reactions to Flexeril can occur. Contact your doctor immediately if you experience side effects that are associated with an allergic reaction. Dangerous side effects to look out for include:

  • Itchiness
  • Shortness of breath
  • Difficulty breathing
  • Tightness in the chest
  • Rash or hives

Side effects which are not associated with an allergic reaction, but still require medical attention include the following:

  • Chest pain
  • Numbness in the arms or legs
  • Quick or irregular heartbeat
  • Tightness in the chest
  • Seizures
  • Weakness on one side of the body
  • Severe dizziness
  • Vomiting
  • Difficulty urinating
  • Yellowing of the skin or eyes
  • Problems with vision or speech
  • Confusion
  • Fainting
  • Hallucinations

These side effects can be indicative of a serious problem. If you experience any of these symptoms, you should consult a medical professional immediately.

Flexeril and Impairment

Many side effects can cause you to feel impaired. You may experience drowsiness, dizziness and an overall impairment in thinking. For this reason, many doctors will recommend that you take Flexeril before bed. If you have a job that requires clear thinking or you plan to be driving or operating heavy machinery, you should not take Flexeril. Wait until you can be assured that you will be at home and out of harm’s way in the event that you should experience these disorienting side effects.

Drinking alcohol can increase these side effects, so avoid consuming alcohol while taking this medication.

Flexeril and the Elderly

For the elderly, some side effects are increased. Drowsiness and dizziness in these patients could lead to a dangerous fall and result in additional injuries. Changes in the mood and mental stability can occur in elderly patients as well. These patients are more susceptible to experiencing heart problems as one of the side effects. Caution should be taken with the elderly when considering Flexeril as a treatment option.

Flexeril Effects and the Liver

Cyclobenzaprine medications can affect the liver. Patients should be mindful of any side effects that indicate liver damage. These include severe pain in the upper right area of the abdomen, dark urine, nausea, low fever, yellowing of the skin and eyes, loss of appetite and clay-colored stools. If you experience these Flexeril side effects, contact your doctor immediately to reduce the risk of serious liver damage.

Many of the more extreme Flexeril side effects, such as drowsiness and dizziness, may be too overwhelming for some patients. This medication is less effective when you cannot spare the time for the rest that you need to recover. For short term treatment of an injury when you have the time to dedicate to the healing process, however, Flexeril will relieve your pain and provide you with a comfortable and restorative rest.