What to Avoid When Taking Naltrexone


Opioid use disorder can happen due to prolonged opioid therapy or through illicit drugs. That said, getting over the addiction can be difficult whatever caused it.

One of the methods that can help with this is by taking low-dose naltrexone. This drug binds to the brain’s opioid receptors and prevents those euphoric and sedative effects of opioids, which in turn makes them less desirable for the patient.

Unfortunately, naltrexone comes with a list of drug interactions that you should keep in mind before using the drug. The most important of which is that you can’t go back to opioids or drink alcohol during therapy.

Let’s take a deeper look at what to avoid when taking naltrexone so you can be informed enough if you’re planning to go through it.

What Is Naltrexone and What Does it Do?

Naltrexone is a part of medication-assisted therapy or MAT that’s used to help patients overcome Opioid use disorder (OUD) or alcohol use disorder (AUD).

This medication works by binding to opioid receptors in the nervous system, stopping opioids from reaching those receptors and producing that “pleasurable” effect that the patient seeks.

Since naltrexone itself doesn’t activate those receptors, it’s safe to use without worrying about addiction.

However, despite being safe to use, there are many drugs that can interact with naltrexone and cause undesirable effects.

The primary problem is that said effects can be highly unpredictable, which is why naltrexone should be handled with extreme caution if the patient is taking any medication that could interact with it.

What Medications Should You Avoid While Taking Naltrexone?

Here’s a shortlist of medications you should stay away from while using naltrexone:

1. Opioids

This may seem obvious, but taking any opioid painkiller during naltrexone therapy isn’t recommended.

It may produce opioid dependence side effects and even elongate the duration of already existing ones.

There’s also the risk of overdosing. Not from naltrexone itself but from whatever opioid the patient is taking along with naltrexone.

This is especially important if the patient isn’t taking the opioid for medical reasons. If a patient is taking an opioid just to “get high,” the opioid won’t achieve its desired effect because of the naltrexone blocking the opioid receptors.

Unfortunately, the patient may make the decision of taking another opioid dose, which can quickly become a fatal overdose.

Note: Some cough medications contain opioids. Those medications are also on the list of prohibited medications that you shouldn’t take with naltrexone.

2. Dextromethorphan

Dextromethorphan is a cough suppressant that has a chemical structure similar to opioids. The drug itself doesn’t lead to addiction because the mechanism of action is different. However, it can still interact with naltrexone and cause unpredictable side effects. Some of those include:

  • Nausea
  • Confusion
  • Vomiting
  • Dizziness
  • Hallucinations and seizures (rare)

Dextromethorphan can also reduce the effectiveness of naltrexone therapy because, despite not working on opioid receptors, it can cause a euphoric feeling as well.

This reduces naltrexone’s ability to minimize opioid cravings and may make it harder for the patient to not go back on opioids.

3. Thioridazine

Thioridazine and naltrexone are both medications whose mechanisms involve affecting the central nervous system. Taking both of these medications together can increase the risk of seizures.

Seizures occur when the level of electrical activity in the brain has passed a certain threshold.

The thioridazine-naltrexone mix will lower that threshold, which dramatically increases the risk of seizures even in healthy individuals.

4. Disulfiram

You might be already aware of this, but naltrexone is also used to treat alcohol use disorder. Disulfiram is another medication that is used for this type of addiction as well.

When both are taken together, they can interact with each other and cause severe side effects. Naltrexone is thought to block the effects of alcohol in the brain’s reward system, while disulfiram works by blocking the breakdown of alcohol in the body, releasing acetaldehyde.

This acetaldehyde is a toxic substance that can cause nausea, vomiting, and sweating.

The lack of that alcoholic high feeling by naltrexone mixed with the undesirable side effects of disulfiram may make the patient drink even more alcohol.

This could lead to even more nausea, vomiting, and painful abdominal cramps. And if the patient decides to ignore their symptoms, they might be vulnerable to alcohol toxicity.

What Physical Conditions Should Keep You Away From Naltrexone?

Even if you’re not taking any of the medications listed above, there are other physical conditions that make naltrexone a less-than-ideal medication for your case.

1. Pregnancy and Breastfeeding

Most medications, including naltrexone, are yet to be extensively tested on pregnant mothers. There’s not enough data on whether the medication can harm the fetus.

That said, naltrexone is definitely excreted in breast milk, but the exact effect on the baby is unknown.

2. Opioid Withdrawal Symptoms

Naltrexone therapy must not start unless the patient has already been through the withdrawal symptoms or at least seven days after the last opioid dose.

Taking naltrexone while the symptoms are still active won’t just increase the severity of the symptoms, it’ll also make them last longer than their usual 7-14 day period.

3. Allergy

While naltrexone allergy isn’t common, it’s still possible for a patient to have severe allergic reactions to it. In naltrexone injections, it might show as blisters and rashes near the injection site.

If the patient is trying naltrexone for the first time, an allergy test is necessary.

4. Kidney and Liver Diseases

Your kidney and liver work hand in hand to help your body break down and remove naltrexone from your system.

The liver breaks down the naltrexone components from your blood, and the kidney filters them out so they can be removed through your urine.

If you have any diseases in either organ, you should inform your doctor. They will run some tests and see whether your body would be able to handle naltrexone therapy.

5. Recent History of Opioid Overdose

If the patient has recently overdosed on any opioid, going on naltrexone therapy isn’t a good idea.

An overdose usually means a longer period of withdrawal symptoms for the next two weeks. Taking naltrexone during this period will exacerbate those side effects and make them potentially life-threatening.

If the patient can’t go through the withdrawal symptoms without the aid of a drug, gradually transitioning from opioids using a partial agonist like buprenorphine can be a useful approach.

Final Words

Naltrexone is among the most common drugs to use against opioid addiction. The mechanism of action makes opioids less desirable, and they can help the patient push through the second phase of therapy.

However, naltrexone should be used with caution, as it can interact with other drugs. It also shouldn’t be used for breastfeeding women or any patient with liver or kidney diseases.

Lastly, naltrexone therapy should be postponed until withdrawal symptoms completelysubside.


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