Missing a single dose of naltrexone is not dangerous and won’t cause withdrawal symptoms or a medical emergency. Unlike opioids or benzodiazepines, naltrexone does not create physical dependence, so skipping a dose won’t trigger the kind of rebound effects you might worry about. What it does is leave a gap in the medication’s protective effect, which matters depending on why you’re taking it.
Why a Missed Dose Matters
Naltrexone works by blocking opioid receptors in the brain. When those receptors are blocked, alcohol feels less rewarding and opioids can’t produce a high. The oral form of naltrexone (typically 50 mg daily) has a relatively short duration of action, with its blocking effect lasting roughly 24 to 72 hours depending on the dose. So missing one dose doesn’t mean the medication vanishes from your system immediately, but its effectiveness starts to taper.
The real risk isn’t a physical reaction from the missed dose itself. It’s what can happen during the window when the medication isn’t fully active. Without naltrexone occupying your opioid receptors, cravings for alcohol or opioids may return or intensify. For people in recovery from opioid use disorder, this window also creates a dangerous scenario: if you use opioids while your tolerance has dropped (which it does while on naltrexone), the risk of overdose is significantly higher than it was before you started treatment.
What To Do When You Miss a Dose
If you remember the same day, take the missed dose as soon as you think of it. If it’s already close to the time for your next scheduled dose, skip the missed one and resume your normal schedule. Do not double up to compensate. Taking two doses at once increases the likelihood of side effects like nausea, headache, and dizziness without providing meaningfully better protection.
If you’ve missed more than one day, simply restart at your regular dose. There’s no need to taper back up or follow a special protocol. Naltrexone doesn’t require the kind of careful reintroduction that some psychiatric medications do. That said, if you find yourself frequently forgetting doses, it’s worth flagging this with your prescriber, because inconsistent use significantly reduces the medication’s effectiveness.
Missed Doses and Alcohol Use Disorder
For people taking naltrexone to reduce drinking, the medication works partly by dulling the pleasurable buzz alcohol normally provides. Clinical trials show that naltrexone reduces heavy drinking days by about 25% compared to placebo, but that benefit depends on consistent use. Missing doses, especially around times when you’re more likely to drink (weekends, social events, stressful periods), can undermine the entire strategy.
Some people take naltrexone using the Sinclair Method, where the pill is taken specifically one hour before drinking rather than daily. If you’re following this approach, “missing a dose” means drinking without having taken the medication first. In that case, the alcohol will feel fully rewarding again, which can reinforce the drinking patterns naltrexone is meant to weaken over time. If this happens, don’t panic, but do take the medication before your next drinking occasion to stay on track.
Missed Doses and Opioid Use Disorder
For people using naltrexone to stay off opioids, a missed dose carries more serious implications. While you’re consistently taking naltrexone, your body’s tolerance to opioids drops substantially. If you miss enough doses for the blocking effect to wear off and then use opioids at the amount you once tolerated, the result can be a life-threatening overdose. This reduced tolerance is one of the most important things to understand about naltrexone treatment.
Even a brief lapse in coverage can be risky if it coincides with a moment of vulnerability. People in early recovery are especially susceptible to impulsive use when cravings spike, and a gap in medication is exactly the moment cravings are most likely to return.
Injectable Naltrexone Avoids This Problem
If missed doses are a recurring issue, the extended-release injectable form may be worth discussing with your provider. Given as a monthly injection, it delivers a steady level of naltrexone for about four weeks, removing the daily decision entirely. Studies show that adherence rates are substantially higher with the monthly injection compared to daily pills, and for opioid use disorder in particular, the injectable form has shown stronger real-world outcomes largely because it eliminates the missed-dose problem.
The tradeoff is that you need to visit a clinic once a month for the injection, and some people experience injection site reactions or more persistent side effects since the medication can’t simply be stopped if you react poorly. But for many people, the reliability outweighs these downsides.
Staying Consistent With Daily Doses
The most common reason people miss naltrexone doses is simple forgetfulness, not intentional discontinuation. A few strategies that help: tie the dose to an existing daily habit like brushing your teeth in the morning, use a pill organizer so you can visually confirm whether you’ve taken it, or set a recurring phone alarm. Some people find that taking it with food reduces the nausea that occasionally leads them to skip doses on purpose.
If side effects like nausea, headaches, or fatigue are the reason you’re skipping, that’s a different problem with its own solutions. These side effects typically peak in the first one to two weeks and then fade. Starting at a lower dose (25 mg) for the first week and then increasing to the full 50 mg can make the adjustment period more tolerable. Persistent side effects beyond the first few weeks are less common but worth addressing with your prescriber rather than quietly stopping the medication.