Alternatives to Naltrexone If You Can't Fill Your Prescription

If you've been unable to fill your naltrexone prescription — whether because of the ongoing shortage of oral tablets or another reason — you are not without options. Several FDA-approved medications can be used in its place, depending on whether you're treating alcohol use disorder (AUD) or opioid use disorder (OUD).

This guide covers the most clinically appropriate alternatives to naltrexone for both conditions, what makes each one different, and what to discuss with your prescriber before making any changes to your treatment plan. Never switch medications without consulting your healthcare provider.

First: Is Vivitrol (Injectable Naltrexone) Available?

Before switching to a completely different medication, ask your prescriber about Vivitrol — the brand-name 380 mg extended-release injectable form of naltrexone. Unlike oral tablets, Vivitrol is not affected by the current shortage. It's administered once a month by a healthcare provider, so it eliminates the need to pick up a monthly prescription. If your insurance covers Vivitrol and your prescriber agrees it's appropriate, this is often the simplest transition.

Vivitrol costs around $1,200 or more per injection without insurance, but Alkermes (the manufacturer) offers a copay savings program (Vivitrol2gether) where 9 out of 10 eligible commercially insured patients pay less than $5 per injection.

Alternatives to Naltrexone for Alcohol Use Disorder (AUD)

The FDA has approved three medications for AUD: naltrexone, acamprosate, and disulfiram. If naltrexone is unavailable, the two main alternatives are:

1. Acamprosate (Campral) — Best for Maintaining Abstinence

Acamprosate works through a completely different mechanism than naltrexone. Where naltrexone blocks the reward of drinking, acamprosate stabilizes the brain's glutamate and GABA neurotransmitter systems — the chemical imbalance that is disrupted by chronic alcohol use. This helps reduce the persistent cravings and anxiety that can drive relapse during early abstinence.

Key advantages over naltrexone: Acamprosate is safe for patients with liver disease (a major benefit, since many people with AUD have impaired liver function). It is also safe to take if you still have opioids in your system — a consideration that does not apply to naltrexone.

Key drawbacks: Acamprosate must be taken three times daily (two 333 mg tablets with each dose, for a total of six tablets per day), which is more complicated than naltrexone's once-daily tablet. It is also not effective if the person has not yet stopped drinking — it is designed for maintaining abstinence, not reducing active drinking.

2. Disulfiram (Antabuse) — For Highly Motivated Patients

Disulfiram takes a completely different approach to treating AUD: it doesn't reduce cravings, but instead causes a deeply unpleasant physical reaction — flushing, nausea, heart palpitations, and vomiting — if you drink any alcohol. This aversive deterrent can be powerful for patients who are highly motivated to avoid drinking entirely.

Important considerations: Disulfiram is one of the older medications used for AUD and has fallen somewhat out of favor due to safety concerns and the need for strict compliance. It requires the patient to be fully committed to abstinence — drinking while on disulfiram can cause serious reactions. Many providers now prefer to use it with supervised administration. Disulfiram is also hepatotoxic and should not be used in patients with significant liver disease.

Alternatives to Naltrexone for Opioid Use Disorder (OUD)

For OUD, the FDA has approved three medications: naltrexone, buprenorphine, and methadone. If naltrexone (either the tablet or injectable Vivitrol) is unavailable, here are the main alternatives:

1. Buprenorphine / Naloxone (Suboxone) — Most Widely Used OUD Medication

Buprenorphine is a partial opioid agonist that partially activates the same opioid receptors that naltrexone blocks. It reduces withdrawal symptoms and cravings without producing a strong high. It's most commonly dispensed as Suboxone — a sublingual film combining buprenorphine with naloxone to deter misuse.

Key difference from naltrexone: Buprenorphine can be started much earlier in the opioid withdrawal process — sometimes as soon as 12-24 hours after last use — whereas naltrexone requires 7-14 days of complete opioid abstinence first. This makes buprenorphine more accessible for many patients. However, buprenorphine is a Schedule III controlled substance with its own prescribing considerations.

Research shows buprenorphine reduces opioid-related death by more than 50% and helps people stay in treatment longer than naltrexone. It is currently the most recommended first-line medication for OUD.

2. Methadone — For Patients Who Need Structured Treatment

Methadone is a long-acting full opioid agonist that reduces withdrawal symptoms and cravings for opioids by keeping the brain's opioid receptors steadily occupied. It is a Schedule II controlled substance and can only be dispensed through federally regulated opioid treatment programs (OTPs), typically requiring daily visits to a clinic.

Methadone has strong evidence for reducing opioid overdose deaths and is especially effective for patients with severe opioid dependence. However, the clinic requirement can be a significant barrier, especially for patients in rural areas or those with transportation challenges.

How to Discuss Alternatives With Your Provider

When speaking with your prescriber about switching medications, be prepared to discuss:

Why you are switching — shortage, side effects, cost, or another reason

Your liver health (relevant for disulfiram and to a lesser extent naltrexone itself)

Whether you are still using opioids (relevant for all OUD medications and for naltrexone in AUD treatment)

Your goals — reducing drinking vs. full abstinence will influence which AUD medication is best for you

Insurance coverage and cost of the alternative medication

Still Looking for Naltrexone First?

If you'd prefer to stay on naltrexone and just need help finding it in stock, medfinder.com can call pharmacies near you to check availability and text you the results.

See our full guide: How to Find Naltrexone in Stock Near You (Tools + Tips).