There is no single “best” time of day to take oral naltrexone. Most patients take it once daily; the right time depends on side effects, your daily routine, and what helps you remember the dose. Oral naltrexone is commonly used for alcohol use disorder and can block opioid effects, but SAMHSA notes that only the long-acting injectable formulation (Vivitrol) is FDA-approved as a medication for opioid use disorder. The monthly Vivitrol injection is given by a clinician on a schedule that doesn’t require a daily decision.
How is naltrexone usually dosed?
The oral form is generic naltrexone 50 mg, most commonly taken as one tablet once daily. ReVia was an older brand name for naltrexone tablets; per FDA records, ReVia was withdrawn from sale, but not for reasons of safety or effectiveness. Higher or alternative dosing regimens (100 mg every other day, 150 mg every third day) are sometimes used to support adherence in alcohol use disorder, per FDA labeling — these alternative schedules are usually used in supervised or adherence-focused settings and should not be started without a prescriber. Per DailyMed, blockade may be reduced with extended intervals and higher single doses may increase hepatocellular-injury risk. Vivitrol is given as a 380 mg intramuscular injection once a month by a healthcare provider.
Morning or evening?
Either is acceptable. Most clinicians recommend taking the dose at the time you are most likely to actually take it — consistency matters more than the exact hour. Some practical considerations:
- Morning — pair with breakfast or a regular morning routine. Some patients report nausea early in treatment, which can be mitigated by taking the dose with food.
- Evening — some patients prefer evening dosing if they experience headache, fatigue, or nausea, since they can sleep through the early hours after a dose.
- With food — can reduce GI side effects.
What if you experience side effects?
Common naltrexone side effects include nausea, headache, dizziness, fatigue, sleep changes, and anxiety, especially in the first weeks. If side effects are bothersome:
- Try shifting the dose to evening so you sleep through them
- Take with food
- Discuss with your prescriber — sometimes adjusting the schedule (every other day, lower starting dose) helps
Most side effects improve over the first 2–4 weeks.
Daily pill vs monthly injection
If remembering a daily dose is the main barrier, the Vivitrol monthly injection may be a better fit. The injection is given in a clinic, and there is no daily decision to make. The trade-off is the in-person visit and the higher cost.
Some patients use the daily pill while early in treatment, then transition to the monthly injection once they are stable.
Adherence tips
- Set a phone alarm for the same time every day
- Pair the dose with another daily habit (brushing teeth, morning coffee)
- Use a weekly pill organizer
- If you miss a dose, take it as soon as you remember unless it’s nearly time for the next dose — do not double up. Follow your prescriber’s instructions, especially if you take naltrexone on a non-daily schedule.
Note: This page is about naltrexone for opioid use disorder and alcohol use disorder. Naltrexone is sometimes used off-label for other conditions; weight-loss combinations are outside the scope of this page.
