Flexeril (cyclobenzaprine) is a muscle relaxant many doctors use for short-term muscle spasms. The right dose depends on your age, health, and other medicines you take. Below are clear, practical rules so you know what to expect and how to use it safely.
For most adults the usual immediate-release dose is 5 mg to 10 mg taken three times a day. Many people start at 5 mg three times daily and increase to 10 mg three times daily if needed and well tolerated. There’s an extended-release form (brand name Amrix) that’s usually 15 mg once daily, sometimes 30 mg once daily. Doctors normally recommend using Flexeril for a short period — typically up to 2 or 3 weeks — because long-term benefit hasn’t been shown.
If you’re over 65, your doctor may start lower or avoid it because older adults are more sensitive to side effects like drowsiness and confusion. People with liver problems may need a lower dose or a different medicine — cyclobenzaprine is processed by the liver.
Take doses at evenly spaced times during the day if you’re on the immediate-release tabs. If it makes you sleepy, try taking your evening dose later or ask your doctor about taking it at bedtime. Don’t mix Flexeril with alcohol or sedatives — it increases drowsiness and the risk of accidents.
If you miss a dose, take it as soon as you remember unless it’s almost time for the next one. Don’t double up. If you stop taking it suddenly after a short course, there’s usually no withdrawal, but if you’ve used it longer or at high doses, check with your prescriber before stopping.
Watch for these common side effects: drowsiness, dry mouth, dizziness, and constipation. If you notice fast heartbeat, fainting, severe confusion, or hallucinations, stop the drug and get medical help. Those are less common but serious.
Avoid Flexeril if you’ve taken a monoamine oxidase inhibitor (MAOI) in the past 14 days — combining them can cause dangerous reactions. Also avoid if you have recent heart attack, significant heart rhythm problems, or uncontrolled hyperthyroidism. Tell your doctor about all prescriptions, over-the-counter drugs, and supplements, especially SSRIs, SNRIs, tramadol, or other serotonergic drugs — combining these can raise serotonin syndrome risk.
Keep pills in their original container, store at room temperature, and keep out of reach of children. Always follow your prescriber’s instructions. If pain or spasms persist beyond a few weeks, ask for a reevaluation — there might be a better long-term plan than continuing Flexeril.
Have questions about your exact dose or safety with other meds? Call your pharmacist or doctor — quick questions can prevent big problems.
