Cyclobenzaprine (Flexeril) During Pregnancy and Breastfeeding: Is it Safe?


A muscle relaxant, cyclobenzaprine (flexeril) is used to help relieve pain, stiffness, and discomfort caused by strains, sprains, or injuries in muscles. Cyclobenzaprine is very closely related to the antidepressant amitriptyline and it is used as a skeletal muscle relaxant to reduce pain and tenderness and improve mobility. However, cyclobenzaprine is not to be used as a treatment for muscle spasm secondary to cerebral or spinal cord diseases.

Read More: 11 Natural Remedies to Relieve Abdominal Pain During Pregnancy

A Guide for Cyclobenzaprine (Flexeril) During Pregnancy and Breastfeeding



Cyclobenzaprine acts on the central nervous system (CNS) to produce its effects to relax the muscles. The action on CNS also causes some of this medicine’s side effects. It may be a muscle relaxant but the medicine does not take place of rest, exercise or physical therapy, or any other treatment that a medical professional may have recommended for the ailment of the medical problem. Cyclobenzaprine is available only with a doctor’s prescription.

This product is available in three types of dosage forms:

  • Capsule, Extended Release
  • Tablet
  • Suspension

Mechanism of action

Cyclobenzaprine does not directly act on the neuromuscular intersection or the muscle. It relieves muscle spasms through a central action, possibly at the brainstem level. Cyclobenzaprine binds to the serotonin receptor and is a receptor antagonist that reduces muscle tone by decreasing the activity of descending serotonergic neurons. There is not enough material on the way cyclobenzaprine acts on the brain but it is considered a good prescription choice for serious, painful sprains and strains, or temporary pain around the skeletal muscles.


The body can quickly build a tolerance to cyclobenzaprine therefore making it less effective in the long run. Although the drug is related to antidepressants cyclobenzaprine, however, acts much faster on the brain than other antidepressant medications that often require one to four weeks to become fully effective. People who take cyclobenzaprine prescriptions have reported that this medication begins working within 20-30 minutes after it is ingested.

Flexeril during pregnancy

The Food and Drug Administration classify Flexeril as Pregnancy Category B. Category B drugs have not shown to cause teratogenicity or fetal abnormalities in animal studies but they have also not been fully evaluated in humans. Category B drugs such as cyclobenzaprine are prescribed during a pregnancy only when the physician has determined and is sure that the risks are less than the benefits of the drug’s actions. Pregnant women, and people with a history of depression or substance abuse problems should not take muscle relaxants.

Pregnant women experience back strain and other pains, particularly in the later stages. Many practitioners recommend natural solutions for the same, which include a warm bath, low-heeled shoes or simply staying off the feet. Often, different sleeping positions such as placing pillows beneath the knees or the purchase of a body pillow, which may help to support the growing belly, also help with the pain. In any case, a physician or health practitioner will help you decide what type of pain treatment you are to seek, especially in case of pregnancy.

Flexeril during breastfeeding

Animal studies done on rats and mice have demonstrated that up to 50 percent of the drug tends to appear in breast milk. Flexeril is to be avoided by nursing women; however, only a medical professional will decide whether you can take Flexeril if you are nursing. There is not enough research on the effects of cyclobenzaprine on human lactation but the studies are ongoing. However, the composition of cyclobenzaprine is similar to tricyclic antidepressants such as imipramine or amitriptyline, which do interact with breast milk. The use of tricyclic antidepressants have known side effects like sinus tachycardia, arrhythmias and stroke. Nursing mothers must use cyclobenzaprine with caution.


This medicine will add to the effects of alcohol and other CNS medicines that slow down the nervous system, possibly causing drowsiness. Cyclobenzaprine causes some people to have blurred vision or drowsiness, dizziness, or less alertness of the senses than normal. It is important to know how one might react to this medicine before driving, using machines, or doing anything else that could be dangerous if one is dizzy or not alert and able to see well.

Abuse of cyclobenzaprine (Flexeril) is on the rise. For example, from 2004-10, there was a 100 percent increase in the number of emergency room visits associated with the drug. That is likely because not only is Flexeril among the most prescribed muscle relaxants but also because abuse of all psychoactive drugs has increased in the last decade.


People take muscle relaxants and expect to be able to function and work normally, including driving, operating machinery or doing cognitive tasks that require focus, which is a huge practical problem. Muscle relaxants make all these tasks harder, even at low doses like opioids. You may think you can ignore the warnings on the packaging, but you shouldn’t.

Drinking is also discouraged while taking a muscle relaxant and this advice is routinely ignored. It should not be unless it is a drink at home before bedtime. It also causes dryness of the mouth. For temporary relief, sugarless candy or gum is suggested and melting bits of ice in your mouth is recommended.  However, continuing dryness of the mouth may increase the chance of a dental disease, including tooth decay, gum disease, and fungus infections therefore it is important to check with your doctor or dentist if the dryness continues for more than two weeks.

Muscle relaxants like cyclobenzaprine, are not recommended for people 65 years or older and there are two reasons for this. Firstly, the sedating effects of the drugs are likely to be more intense in older people, who are already at higher risk of falls and home or workplace accidents and secondly, many people aged 65 and older take other medicines that could interact with muscle relaxants in adverse ways.

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