Flexeril (Cyclobenzaprine) at a glance: schedule, half-life, and class
- Generic name
- Cyclobenzaprine hydrochloride
- Brand names
- Flexeril (discontinued brand), Fexmid, Amrix (extended release)
- Drug class
- Centrally acting skeletal muscle relaxant
- US legal status
- Prescription only; not controlled
- Approved uses
- Muscle spasm from acute, painful musculoskeletal conditions, for 2 to 3 weeks
- Forms
- Tablets (5, 7.5, 10 mg); extended-release capsules (15, 30 mg)
- Onset
- About 1 hour
- Half-life
- About 18 hours
Flexeril uses: what cyclobenzaprine is prescribed for
Cyclobenzaprine relieves muscle spasm from strains, sprains, and back pain, alongside rest and physical therapy. It is approved for 2 to 3 weeks because evidence for longer use is lacking.[1]
It works in the brainstem rather than directly on muscles, and its structure is close to the antidepressant amitriptyline.[1]
Flexeril dosage: how cyclobenzaprine is usually prescribed
The figures below come from the FDA-approved label and describe how prescribers typically use cyclobenzaprine. They are not personal dosing advice. A prescriber sets the dose for each person and adjusts it over time.[1]
| Product | Typical adult dose | Notes from the label |
|---|---|---|
| Tablets | 5 mg three times a day | May increase to 10 mg three times a day |
| Extended-release capsules | 15 mg once a day | Up to 30 mg once a day |
| Older adults or mild liver impairment | Start with 5 mg, less often | Avoid extended release |
Flexeril (cyclobenzaprine) side effects and risks
Common side effects include drowsiness, dry mouth, dizziness, fatigue, and constipation.[1]
Heart: like tricyclics it can cause fast or irregular heart rhythms. It should not be used after a recent heart attack, with heart block, arrhythmias, heart failure, or an overactive thyroid.[1]
Older adults: it is on the list of medicines to avoid in older adults because of confusion and falls.
Misuse: some people combine it with opioids or alcohol to intensify sedation, which raises overdose risk.
Flexeril interactions: what not to mix with cyclobenzaprine
Choose what it would be combined with:
| Combined with | What happens | Label guidance |
|---|---|---|
| MAO inhibitors (within 14 days) | Seizures, high fever, death | Contraindicated |
| SSRIs, SNRIs, tramadol, bupropion, triptans | Serotonin syndrome | Use caution |
| Alcohol, opioids, benzodiazepines | Additive sedation and slowed breathing | Avoid or use caution |
| Anticholinergic drugs | Urinary retention, confusion, overheating | Use caution |
This is not a full list. A pharmacist can check a complete medication list, including supplements and over-the-counter products.[1]
Flexeril overdose: signs of cyclobenzaprine overdose and what to do
Overdose causes drowsiness, fast heartbeat, agitation, hallucinations, and, at high doses, dangerous heart rhythms, seizures, and coma, similar to tricyclic antidepressant poisoning.[1]
If someone may have taken too much
- Call 911 for fainting, a seizure, chest pain, a racing or irregular heartbeat, confusion, or if the person cannot be woken.
- If the person collapses and is not breathing normally, start CPR and use an AED if one is available.
- Give naloxone if opioids could be involved. It is safe even if they are not.
- For advice when the person is awake and stable, call Poison Help at 1-800-222-1222 (US, free, 24 hours). Bring the product packaging to the hospital.
Flexeril withdrawal timeline: how long cyclobenzaprine withdrawal lasts
Cyclobenzaprine does not usually cause dependence. Stopping after long-term daily use can cause temporary discomfort.[1]
- Days 1 to 3Possible symptomsNausea, headache, and feeling unwell.
- Within a weekResolvesSymptoms are usually mild and short-lived.
- Ongoing painReassessExercise and physical therapy help more over time.
How to get prescribed Flexeril (cyclobenzaprine) legally in the US
In the United States, cyclobenzaprine is a prescription-only medicine. It is not a federal controlled substance, so the only legal way to get it is with a prescription from a licensed clinician, filled by a licensed pharmacy.
- Refills: refills follow ordinary prescription rules.
- Pharmacies: a legitimate pharmacy always requires a valid prescription, has a licensed pharmacist available, and is licensed in the state it ships to. The FDA's BeSafeRx tool and the NABP's safe pharmacy list help confirm a pharmacy is real.[2][3]
- Cost: generic cyclobenzaprine tablets are among the least expensive prescription medicines.
Traveling: keep the medicine in its original pharmacy container and carry a copy of the prescription. Check the rules of the destination country before travel, because many countries restrict controlled medicines or require a permit.
Can you order Flexeril (cyclobenzaprine) online legally?
Yes, but only with a valid prescription and only from a pharmacy licensed in your state. Many licensed pharmacies, including mail-order pharmacies run by insurers, fill cyclobenzaprine prescriptions online and ship them. Buying cyclobenzaprine from a website that does not require a prescription is illegal, and the product is often fake.[2][4]
- See a licensed clinicianA clinician evaluates you in person or by telemedicine and decides whether cyclobenzaprine is appropriate.
- The prescription goes to a pharmacyPrescriptions are usually sent electronically, straight from the prescriber to the pharmacy you choose.
- The pharmacy checks and fills itA pharmacist verifies the prescription and your identity, then dispenses the medicine in person or by mail.
Signs that an online seller is illegal:
- It sells cyclobenzaprine with no prescription, or after only a short online questionnaire.
- It takes orders through social media, messaging apps, or email.
- It asks for payment in cryptocurrency, gift cards, or money transfers.
- It has no US street address, no state pharmacy license, and no pharmacist to speak to.
- Its prices are far below those of ordinary pharmacies, or it ships from another country.
The FDA's BeSafeRx tool links to each state's license lookup, and the National Association of Boards of Pharmacy lists verified online pharmacies.[2][3]
Flexeril price: how much does Flexeril (cyclobenzaprine) cost without insurance?
Generic cyclobenzaprine tablets are among the least expensive prescription medicines.
What you pay depends on the strength, the number of doses, your insurance plan, and the pharmacy. Cash prices for the same prescription can differ several times over between pharmacies in the same town, so check current prices before you fill it.
Ways to pay less, legally:
- Ask the prescriber whether a generic cyclobenzaprine is available. FDA-approved generics work the same way as the brand and usually cost much less.
- Compare cash prices between pharmacies before you fill the prescription.
- Use a free prescription discount card, such as GoodRx or SingleCare, when you pay cash. These cards cannot be combined with insurance on the same fill.
- For brand-name medicines, check the manufacturer's savings program or patient assistance program.
- Ask about a 90-day supply or your insurer's mail-order pharmacy, which often lowers the cost per dose when your prescriber agrees it is appropriate.
Warning: A price far below what licensed pharmacies charge, especially with no prescription required, is a strong sign of an illegal seller and counterfeit medicine.[2]
Is Flexeril legal? Cyclobenzaprine legal status in other countries
| Country | Status |
|---|---|
| Canada | Prescription only |
| United Kingdom | Not licensed |
| International | Not under UN control |
Laws change and differ in detail. Check current rules before carrying any controlled medicine across a border.[5]
Common questions about Flexeril (cyclobenzaprine)
Is Flexeril (cyclobenzaprine) a narcotic?
No. It is not an opioid or a controlled substance.
Will Flexeril (cyclobenzaprine) make me sleepy?
Very likely. Drowsiness is its most common side effect, so many people take it at night.
Can you take Flexeril (cyclobenzaprine) with ibuprofen?
Yes. They are often used together for back pain.
Can Flexeril (cyclobenzaprine) be taken with antidepressants?
With caution. It can cause serotonin syndrome with SSRIs and SNRIs and must not be taken with MAO inhibitors.
How long can I take Flexeril?
It is approved for 2 to 3 weeks.
Can you buy Flexeril (cyclobenzaprine) without a prescription?
No. Flexeril (cyclobenzaprine) is a prescription-only medicine in the US, and a pharmacy may dispense it only with a valid prescription. The FDA warns that websites selling prescription medicines without one are often illegal and that their products can be counterfeit, contaminated, or the wrong strength. The legal route is a visit with a licensed clinician, in person or by telehealth, and a prescription filled at a state-licensed pharmacy. The FDA's BeSafeRx tool and the NABP's safe pharmacy list help confirm an online pharmacy is real.
Sources
- Flexeril (cyclobenzaprine) prescription information. DailyMed, US National Library of Medicine.
- BeSafeRx: Your Source for Online Pharmacy Information. US Food and Drug Administration.
- Safe Pharmacy. National Association of Boards of Pharmacy.
- One Pill Can Kill. US Drug Enforcement Administration.
- International drug control conventions. United Nations Office on Drugs and Crime.
