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Reviewed by Cyclobenzaprine hydrochloride, commonly known as Flexeril, is a low-cost and effective treatment for painful musculoskeletal conditions. It reduces localized pain and tenderness.
Even though muscle relaxers are not a first-line treatment for muscle pain, Flexeril has become a go-to adjunct therapy for pain, with over 14 million prescriptions in the U.S. This medication can give you back your range of motion after a strained muscle. Yet, you may experience some cyclobenzaprine side effects in the process.
Continue reading to learn about the side effects of cyclobenzaprine, its symptoms, and tips for care and management.
Table Of Contents:
Cyclobenzaprine Overview
Cyclobenzaprine, under the brand name Flexeril, is a centrally acting skeletal muscle relaxant structurally similar to tricyclic antidepressants.
Cyclobenzaprine works by inhibiting brain and spinal cord pathways, which helps reduce muscle stiffness and spasms. Calming these nerve pathways decreases muscle overactivity, leading to less pain and more mobility.
Although it is effective in decreasing muscle spasms and improving pain and mobility, you can feel sleepy and constipated during cyclobenzaprine treatment. Letโs review these Flexeril side effects:
What Are The Cyclobenzaprine Side Effects?
When cyclobenzaprine is prescribed under a doctor’s supervision, the adverse effects are commonly mild and manageable. Around 1% to 3% of patients will experience them, and they are almost all related to the anticholinergic effects of cyclobenzaprine.
Here we provide a list for you to know what to expect:
Drowsiness
Cyclobenzaprineโs strong anticholinergic properties block the action of acetylcholine, a neurotransmitter involved in transmitting nerve impulses (wakefulness and alertness) in the brain and throughout the body.
Anticholinergic drugs can inhibit acetylcholine, reducing the overall activity of the central nervous system (CNS). This blockage is why sedation is the most frequent cyclobenzaprine side effect, prevalent at the standard dosage of 10 mg taken three times a day.
If you are feeling sleepy while using Flexeril, you can:
- Explore with your doctor, lowering your dose. Cyclobenzaprine 5 mg or 2.5 mg can reduce sedation.
- Take cyclobenzaprine in the evening to manage daytime drowsiness.
- Donโt mix cyclobenzaprine and alcohol, as it can aggravate sedation.
- Keep track of how you feel and report any persistent or severe sedation to your doctor.
Dry Mouth (Xerostomia)
Due to cyclobenzaprineโs anticholinergic properties, you may feel thirsty and constantly dry or sticky in the mouth. This is another of the cyclobenzaprine side effects caused by inhibiting acetylcholine that interrupts the neural stimulation of saliva secretion, reducing saliva flow and leading to hyposalivation.
You can manage cyclobenzaprineโs dry mouth effects by:
- Drink water throughout the day to keep your mouth moist.
- Limiting intake of caffeine, alcohol, and tobacco, as they can worsen dry mouth.
- Use an alcohol-free mouthwash designed for dry mouth to avoid further irritation.
- Over-the-counter saliva substitutes or oral moisturizers can provide temporary relief.
- Chewing sugar-free gum or candy to stimulate saliva flow. Look for products containing xylitol.
Flexeril Side Effects Blood Pressure
If you have been feeling lightheaded, dizzy or about to faint, you may have wondered: Does Flexeril lower blood pressure? The answer is yes. Changes in blood pressure are another side effect of cyclobenzaprine.
However, hypertension has also been reported. Cyclobenzaprine’s anticholinergic properties can cause vasodilation (relaxation and widening of blood vessels), which may result in lower blood pressure. The mechanism by which cyclobenzaprine may cause hypertension is not well understood yet. It could be a potential individual reaction to the medication.
To keep yourself safe from a potential change in your blood pressure, you can:
- Regularly monitor your blood pressure, especially when starting or adjusting the dosage.
- Limit alcohol as it can exacerbate dehydration and hypotension.
- Rise slowly from sitting or lying down positions.
- Use support like handrails or furniture when getting up to prevent falls.
- Maintain a diet that supports cardiovascular fitness, including a healthy salt intake.
- Inform your doctor about any episodes of dizziness, lightheadedness or fainting.
Headaches
Blockage of acetylcholine by cyclobenzaprine also affects the regulation of muscle activity and vasodilation, which can lead to vasoconstriction (narrowing of blood vessels), reducing blood flow to the brain and potentially causing cyclobenzaprine side effects such as headaches.
Headaches shouldnโt be severe, and you may manage them at home with:
- Your doctorโs approval, take over-the-counter medication (Tylenol or Advil).
- Apply a cold or warm compress to the forehead or neck.
- Avoid combining cyclobenzaprine with other CNS depressants without medical advice.
- Regular exercise can help reduce tension and prevent headaches.
- Limit screen time to rest your eyes and reduce visual overstimulation.
Confusion
Drowsiness caused by Flexeril can make it harder to focus and be alert. This side effect can be more severe if you take cyclobenzaprine with alcohol or other medications that also cause drowsiness. Cyclobenzaprine side effects in the elderly and people taking doses above 5 mg might be more severe.
To manage cyclobenzaprine-induced confusion, you can:
- Discuss with your doctor the possibility of reducing the dosage.
- Take the medication in the evening or before bedtime to avoid daytime confusion.
- Use tools like calendars, alarms, and lists to help you remember daily tasks.
- Ensure you get enough restful sleep each night.
- Avoid alcohol intake as it can exacerbate the cyclobenzaprineโs sedative and cognitive effects.
- Keep track of your symptoms and report them to your doctor.
Other Cyclobenzaprine Side Effects
The following side effects of cyclobenzaprine are considered rare. If you are experiencing any of the symptoms below, seek immediate medical attention.
- Agitation
- Hallucinations
- Fever
- Shivering
- Rapid heart rate
- Sweating
- Muscle stiffness or twitching
- Allergic reactions (severe rash or hives, swelling, difficulty breathing)
- Irregular heartbeat
- Palpitations
- Chest pain
The first seven symptoms are caused by serotonin syndrome, which is one of the cyclobenzaprine warnings.
This is a rare but severe condition caused by excessive serotonin in the brain. Although cyclobenzaprine alone has a small effect on serotonin, the risk increases when combined with other serotonin-affecting medications like SSRIs, SNRIs, and triptans.
Cyclobenzaprine Long-Term Side Effects
When taken over an extended period, cyclobenzaprine can lead to several long-term side effects, including:
- Tolerance
- Dependence
- Cognitive impairment
- Liver damage
- Mood swings
- Muscle weakness
- Abuse, drug addiction, and overdose
Since the drug has not proven effective in treating muscle spasms and pain after a maximum of three weeks, there is no need for prolonged cyclobenzaprine use.
Cyclobenzaprine Side Effects โ Bottom Line
Cyclobenzaprine is an affordable muscle relaxant that alleviates muscle spasms and associated pain. However, its various side effects, including drowsiness, dry mouth, dizziness, headaches, and confusion, can be the primary reason for discontinuing treatment.
Long-term use can result in tolerance, dependence, cognitive impairment, and mood changes. Given the potential for abuse and dependence, it is vital to limit the use of cyclobenzaprine to a maximum of three weeks. Discuss alternative treatments to ensure safe and effective care if muscle spasms persist after this period.
Remember that individuals with cyclobenzaprine addiction may require addiction treatment, including drug detox and rehabilitation programs. A local rehab center can offer you guidance and support to start addiction recovery.
People Also Ask
How long does cyclobenzaprine side effects last?
Cyclobenzaprine side effects like drowsiness can hit within 30 minutes and last 4-8 hours, depending on the strength. Talk to your doctor if side effects linger or become bothersome.
Does Flexeril raise blood pressure?
There are reports of Flexeril causing high blood pressure. However,ย the reason behind it is not understood, and it may be attributed to individual interactions with the drug or underlying health issues.
Does Flexeril cause weight gain?
Flexeril itself shouldn’t cause weight gain. However, reduced activity due to pain or strained muscles might indirectly affect your weight.
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Page Sources
- Cyclobenzaprine - Drug usage Statistics, ClinCalc DrugStats Database. https://clincalc.com/DrugStats/Drugs/Cyclobenzaprine
- Khan, I., & Kahwaji, C. I. (2023, August 28). Cyclobenzaprine. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK513362/
- Bryant Ranch Prepack. (2023). Cyclobenzaprine hydrochloride [package insert].
- Borenstein, D. G., & Korn, S. (2003). Efficacy of a low-dose regimen of cyclobenzaprine hydrochloride in acute skeletal muscle spasm: Results of two placebo-controlled trials. Clinical Therapeutics, 25(4), 1056โ1073. https://doi.org/10.1016/s0149-2918(03)80067-x
- Arany et al. (2021). Anticholinergic medication: Related dry mouth and effects on the salivary glands. Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 132(6), 662โ670. https://doi.org/10.1016/j.oooo.2021.08.015
- Chabria, S. B. (2006). Rhabdomyolysis: a manifestation of cyclobenzaprine toxicity. Journal of Occupational Medicine and Toxicology, 1(1), 16. https://doi.org/10.1186/1745-6673-1-16
- Sam, C., & Bordoni, B. (2023, April 10). Physiology, acetylcholine. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK557825/
- Long-term use of muscle relaxants has skyrocketed since 2005 - Penn Medicine. (n.d.). https://www.pennmedicine.org/news/news-releases/2020/june/long-term-use-of-muscle-relaxants-has-skyrocketed-since-2005