Cyclobenzaprine Interactions You Should Know

Cyclobenzaprine Interactions: Introduction

Cyclobenzaprine is a muscle relaxant that relieves the pain caused by strains, sprains, and other injuries. When over-the-counter (OTC) medications do not help, your doctor may prescribe cyclobenzaprine for two to three weeks to relax the muscle spasm alongside physical therapy and rest. (1-2)

Sounds great to know that, finally, the pain will be gone. But, before beginning the therapy, have you told your doctor the medications you take? Have you thought that cyclobenzaprine might interact with the treatment you’re using, and is it safe?

In over 40 years of post-marketing clinical experience, there are reports of cyclobenzaprine interactions with some medications, such as central nervous system (CNS) depressants, that require close monitoring due to side effects. Some interactions, like cyclobenzaprine with monoamine oxidase (MAO) inhibitors, can be life-threatening, so this concomitant treatment is contraindicated. (1)

In this article, you can read all you need to know about the interactions of cyclobenzaprine with other medications. You can also learn the contraindications and other helpful advice on safe usage.

Cyclobenzaprine Interactions with Other Medications

Cyclobenzaprine relieves pain by relaxing the skeletal muscles without affecting muscle function. It acts within the central nervous system at the brainstem, influencing specific neurons (gamma and alpha motor neurons). As a result, cyclobenzaprine relaxes and reduces muscle tension and spasm. (1)

Cyclobenzaprine, taken with certain medications simultaneously, increases the risk of side effects by interacting with drugs in several excitable structures (for example, the brain, heart, and blood vessels). Keep reading to understand what interactions require monitoring and additional caution and which are not recommended.

Cyclobenzaprine and Tramadol

When cyclobenzaprine is administered with tramadol, it can enhance the seizure risk. It may happen because cyclobenzaprine lowers the seizure threshold and increases the risk of having seizures. This risk is more likely to occur at doses over 1.000 mg, which is much more than the recommended maximum daily dose of 30 mg. Still, considering the safety risk, the doctor will make the best judgment if this combination is beneficial. (1, 3)

Serotonin Syndrome

After its approval for use, serotonin syndrome was reported when cyclobenzaprine was used with medications that increase serotonin levels in the body, like tramadol, bupropion, meperidine, and verapamil. (1)

Serotonin syndrome is a rare but life-threatening drug reaction caused by using a specific combination of medications. It can occur when an antidepressant is used with an opioid pain medication and, as a result, the level of serotonin is high. Serotonin syndrome happens at the initiation of the treatment or when the dose is increased. (4)

The body produces serotonin, the happy hormone, that plays an essential role in our mood, happiness, and brain function. High serotonin levels are harmful, causing shivering, diarrhea, and more severe symptoms such as muscle rigidity, fever, and seizures. (4)

Selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), and MAO inhibitors are medications that increase serotonin levels and improve depression. Using these together with cyclobenzaprine puts the patient at risk for serotonin syndrome. (4)

The symptoms of serotonin syndrome include the following: confusion, agitation, hallucinations, tachycardia, labile blood pressure, hyperthermia, tremor, ataxia, muscle rigidity, nausea, vomiting, and diarrhea. If any of these symptoms occur while you use the combo treatment, discontinue the therapy immediately and call your doctor. In such a situation, medically supportive symptomatic treatment is necessary. (4)

Because of it, the pain treatment with cyclobenzaprine is contraindicated, while the patient uses MAO inhibitors for depression. (1)

Concomitant Use with CNS Depressants

Using cyclobenzaprine with CNS depressants can be dangerous because it amplifies the drugs’ effects. The side effects associated with sedatives that might occur and get worsen are sleepiness, forgetfulness, and trouble concentrating.

Cyclobenzaprine, in combination with a CNS depressant, can lead to an increased concentration of cyclobenzaprine. As a result, the patient can experience the overdose symptoms such as drowsiness, fast or irregular heartbeat, confusion, trouble speaking or moving, hallucination, loss of consciousness, etc.

Alcohol, barbiturates, and tramadol are some of the CNS depressants that slow down the brain and negatively interact with cyclobenzaprine. Call the poison control helpline at 1-800-222-1222 if you experience overdose symptoms. If a person using cyclobenzaprine loses consciousness, has trouble breathing, or can’t be awakened, immediately call emergency services at 911. (2)

Cyclobenzaprine and Alcohol

Alcohol should be avoided when you are on medication treatment. In many cases, alcohol intensifies the side effects of the medications and, in some cases, can be dangerous. (5)

Cyclobenzaprine is a muscle relaxer that does not allow nerve signals to come to the brain. At the same time, cyclobenzaprine side effects like drowsiness, dizziness, dry mouth, or agitation, together with the depression that alcohol causes on CNS, can be exacerbated with alcohol. (5)

For this reason, avoid consuming alcohol when taking cyclobenzaprine.

Guanethidine: Antihypertensive Effect May Be Blocked

Guanethidine is an antihypertensive used for the treatment of high blood pressure. It controls the impulses of the nerves and relaxes the blood vessels. When guanethidine is used with cyclobenzaprine, cyclobenzaprine may block the antihypertensive effect of guanethidine. (1, 6)

Side Effects, Contraindications, and Warnings When Using Cyclobenzaprine

Cyclobenzaprine, like any other medication, has some side effects. Dry mouth, nausea, dyspepsia, fatigue, dizziness, constipation, and somnolence are the most common adverse reactions of cyclobenzaprine that are greater than placebo. (1)

Due to hyperpyretic crisis seizures and deaths that may occur in patients while using cyclobenzaprine and MAO inhibitors, concomitant use with MAO inhibitors or within 14 days after their discontinuation is not recommended.

You should also know that cyclobenzaprine is contraindicated if you are allergic to the active or any other component of this medication. In addition, patients recovering after myocardial infarction and those with arrhythmias, heart block, conduction disturbances, or congestive heart failure should not use cyclobenzaprine.

Because of the risk for serotonin syndrome, cyclobenzaprine treatment in combination with SSRIs, SNRIs, TCAs, bupropion, tramadol, verapamil, and meperidine should be immediately discontinued if you notice any of the following symptoms:

confusion, agitation, or hallucinations as a result of mental status changes;
nausea, diarrhea, and vomiting;
diaphoresis, tachycardia, labile blood pressure, hyperthermia due to autonomic instability;
tremor, ataxia, hyperreflexia, clonus, and muscle rigidity due to neuromuscular abnormalities.

Cyclobenzaprine has a structure similar to TCAs and shows similar activity, but also it may develop serious CNS reactions similar to TCAs’ side effects. This can be a reason for cyclobenzaprine treatment discontinuation.

Cyclobenzaprine is not recommended for the elderly because its concertation could be much higher than in young adults.

How is Cyclobenzaprine Used?

Cyclobenzaprine is packed in capsules and can be used once or twice daily. The usual recommended dose for adults is one capsule of 15 mg once daily. However, in some cases, the doctor may prescribe 15 or 30 mg twice daily. (1)

Take the dose at the same time every day, as long as your doctor recommends it to you. Cyclobenzaprine is not recommended for treatment longer than 2 to 3 weeks. (1)

If you cannot swallow capsules, sprinkle the content on the tablespoon of applesauce and take it immediately. Rinse after the mouth to ensure you have swollen the whole content without chewing. (1)

Final thoughts

Pain can be strong and unbearable; however, when struggling to find an effective pain reliever, remember that the medication should help and not cause additional harm. Cyclobenzaprine can be safely used if you follow the doctor’s recommendations and be aware of possible interactions and contraindications.

Tell your doctor if you use any other medication but are unsure if it can interact with cyclobenzaprine. For example, don’t start using cyclobenzaprine if you are allergic or using an MAO inhibitor.

Read the Medication Guide and learn about this medication and its possible side effects. Report adverse events to your doctor or the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online https://www.fda.gov/safety/medwatch-fda-safety-information-and-adverse-event-reporting-program) or by phone (1-800-332-1088).

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