Low Dose Naltrexone: What to Avoid While Taking It, According to Experts

When taking low-dose naltrexone (LDN), avoid alcohol and all opioids, including opioid cough medicines and loperamide (Imodium), and avoid benzodiazepines unless your prescriber decides otherwise. Common side effects include headaches, dizziness, drowsiness, and stomach or bowel symptoms, and mild side effects will likely subside as your body adjusts.

Naltrexone is an FDA-approved drug to help treat opioid use disorder (OUD) and alcohol use disorder (AUD). The recommended dosage for these two disorders is typically 50 to 100 milligrams of the naltrexone oral tablet each day. However, some people may benefit from low-dose naltrexone (LDN) treatment.

This prescription medication is an opioid receptor antagonist, which means it blocks opioids from binding to opioid receptors in the brain. Put simply, this means that naltrexone blocks the pleasurable effects that alcohol or opioids typically bring. If drinking alcohol or taking opioids doesn’t get you high or make you feel good, you’re less likely to consume them. This is how naltrexone treatment helps people get sober and stay sober.

Although the typical dose for AUD and OUD is generally higher, some people may benefit from LDN treatment, although this approach isn’t necessarily FDA-approved. “The primary goal of low-dose naltrexone in the context of AUD and OUD is to gradually diminish cravings and [substance use] behavior while minimizing adverse effects, particularly for people who do not tolerate conventional doses adequately,” says Dr. Shanard Clemons, Ed.D, LAPC, NCC, a Charlie Health Group Facilitator. 

Here’s what you need to know about what to avoid when taking LDN, who shouldn’t take the medication, what the side effects are, and more.  

What is low-dose naltrexone (LDN)?

Low-dose naltrexone is naltrexone taken at a much lower dose than the 50 to 100 mg used for alcohol and opioid use disorder. Peer-reviewed reviews describe it as typically about 0.5 to 6 mg a day, and most studies use 4.5 mg. LDN is prescribed off-label, is not FDA-approved for any medical condition, and is generally supplied by compounding pharmacies, so strength and quality can vary. The same reviews say current evidence does not support routine clinical use.

How is low-dose naltrexone different from regular naltrexone?

Standard naltrexone for alcohol use disorder and opioid use disorder is typically 50 to 100 milligrams a day and is FDA-approved for those conditions, while low-dose naltrexone uses a lower dose and is not FDA-approved for any medical condition. According to Charlie Health Group Facilitator Dr. Shanard Clemons, side effects at low doses are usually less severe than at higher levels, though they can still occur, and LDN may suit people who do not tolerate conventional doses adequately. What you should avoid is the same whether you take a lower dose or a higher dose.

What should you avoid when taking low-dose naltrexone?

Various interactions can occur when taking LDN. Here’s what you should avoid when taking naltrexone, whether you are taking a lower dose or a higher dose. 

1. Alcohol

You should avoid alcohol while taking LDN. Naltrexone blocks the “buzz” or feeling of intoxication from alcohol. However, it can still lead to poor judgment, slowed reflexes, and reduced coordination, says Nicole Lonano, MS, a Charlie Health Group Facilitator. So, even though you might not necessarily feel drunk, your impairment, loss of motor coordination, and slowed response time can make activities like driving dangerous, she says. 

2. Opioids

“Consuming opioids while on naltrexone can cause severe and hazardous opioid withdrawal,” Dr. Clemons says. This is known as precipitated withdrawal, and the withdrawal symptoms may be very intense. You should not take naltrexone if you’ve had any opioid use within the last 7-10 days. Avoid any opioid medication and illicit opiates, including: 

• Buprenorphine
• Codeine
• Fentanyl
• Heroin
• Hydrocodone
• Methadone
• Morphine
• Oxycodone
• Oxymorphone
• Tramadol

“Consuming any of the mentioned substances increases your risk of experiencing side effects such as nausea, dizziness, headaches, liver damage, or interference with normal opioid receptor activity,” Dr. Clemons says. 

Note that opioids might show up where you don’t necessarily expect them to. For example, some cough medications contain opioids (codeine or hydrocodone). Additionally, even some diarrhea medicines like loperamide (the generic name for Imodium) are technically an opioid. 

This is not an exhaustive list of drug interactions. Make sure to always tell your providers about all the medications you’re taking so that they can check for interactions and keep you safe. You want to ensure that you won’t experience any type of precipitated opioid withdrawal.

What painkillers can you take with low-dose naltrexone?

The best plan is to ask your prescriber and pharmacist before taking any pain medicine. The naltrexone label says people taking naltrexone may not benefit from opioid-containing medicines, such as opioid pain relievers and cough, cold, and antidiarrheal products, and that in an emergency doctors may use regional anesthesia, non-opioid pain medicines, or other approaches. Tell every clinician, including your dentist, that you take naltrexone, and consider carrying identification. For planned surgery, a national guideline for standard-dose oral naltrexone recommends stopping it 72 hours before surgery and treating mild pain with NSAIDs, but that guidance isn’t specific to low doses, so ask your surgeon, anesthesiologist, and prescriber about your plan.

3. Benzodiazepines

Benzodiazepines, or “benzos,” are a class of central nervous system depressants, meaning they slow down brain and nervous system activity. They are most commonly used to treat panic disorder and severe anxiety.

“Benzos should be avoided due to the increased risk of adverse effects like overdose. Benzos typically interfere with the effectiveness of naltrexone,” Dr. Clemons says. “However, some doctors may prescribe benzos to patients and monitor them for any adverse effects.” Ultimately, it will be on a case-by-case basis. 

Who should avoid taking low-dose naltrexone?

LDN treatment is not a fit for everyone. Dr. Clemons says the following groups should avoid LDN treatment, or use it with caution due to potential hazards or interactions:

• Current opioid use
• Active alcohol dependence or use without a sobriety plan
• Severe liver disease or liver impairment
• Kidney disease 
• Pregnancy 
• Breastfeeding

Additionally, if you have a history of mental health conditions or currently have a mental health condition (other than substance use disorder), it’s important to tell your provider. It’s possible for naltrexone to worsen these conditions. If you struggle with depression, carefully monitor your symptoms. If you’re experiencing suicidal thoughts, don’t hesitate to reach out for help ASAP. Call or text the 988 Lifeline for 24/7 support from a crisis counselor. 

What are the side effects of low-dose naltrexone?

“Low-dose naltrexone, like standard-dose naltrexone, is typically well tolerated, but some people may develop side effects, particularly when beginning treatment,” Dr. Clemons says. “Side effects at low doses are usually less severe than at higher levels, but they can still occur.”

Potential naltrexone side effects include:

• Headaches
• Dizziness
• Drowsiness 
• Gastrointestinal symptoms (like nausea, vomiting, stomachache, constipation, or diarrhea)
• Loss of appetite
• Nervousness or anxiety
• Trouble sleeping
• Irritability 

If you experience a mild adverse effect, it will likely subside as your body adjusts to the medication. But if an adverse effect doesn’t subside or worsens, let your provider know. This isn’t an exhaustive list of side effects. You can see more information here.

Additionally, there is a risk of serious side effects. If you experience any of the following, tell your provider right away: 

• Blurred vision
• Hallucinations
• Confusion
• Severe diarrhea or vomiting 

How long do LDN side effects last?

No source gives a specific number of days or weeks. Reviews describe LDN side effects as usually mild and short-lived, most often insomnia, vivid dreams, nausea, and dizziness, and say sleep-related effects often improve with continued use or when the dose is taken in the morning instead of at bedtime. If side effects don’t go away or get worse, tell your provider.

Are low-dose naltrexone side effects different for women?

The naltrexone label doesn’t report different side effects in women, and there is little research on sex differences at low doses. Small studies at the standard 50 mg dose found that women in the luteal phase of the menstrual cycle had stronger hormonal and subjective responses to a single dose, while another study found that naltrexone’s effect over placebo appeared similar in women and men. The label says studies of interactions with drugs other than opioids have not been performed. It also says naltrexone should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, and that caution should be used when nursing because it is unknown whether naltrexone passes into human milk. Tell your prescriber if you are pregnant, planning to become pregnant, or breastfeeding.

What are the symptoms of taking too much low-dose naltrexone?

There is very little human data. The label says clinical experience with naltrexone overdose is limited, and that in one study people who took 800 mg a day for up to a week showed no evidence of toxicity, but it doesn’t list overdose symptoms for people. If you think you or someone else took too much, call Poison Help at 1-800-222-1222, and call 911 if the person has collapsed, had a seizure, has trouble breathing, or can’t be awakened. If you miss a dose, MedlinePlus says to take it as soon as you remember unless it is almost time for your next dose, and not to take a double dose.

Can low-dose naltrexone make you feel high?

No. The label describes naltrexone as an opioid antagonist with no opioid agonist properties that does not lead to physical or psychological dependence, and a review of LDN research says it does not exert euphoric or reinforcing effects, although that reflects one research group’s small studies. What you might notice instead are side effects such as dizziness, drowsiness, or anxiety. Don’t try to overcome naltrexone’s blockade with large amounts of opioids: the label warns that doing so may lead to serious injury, coma, or death.

How long does naltrexone stay in your system, and can you stop it suddenly?

The label gives an average half-life of about 4 hours for naltrexone and 13 hours for its main active metabolite. Naltrexone isn’t associated with dependence, but MedlinePlus says not to stop taking it without talking to your doctor, because it helps you avoid alcohol and opioids only as long as you take it. The label also warns that after treatment is stopped, people may be more sensitive to opioids, even at lower doses, so tell your prescriber about any opioid use. No source gives a standard time to notice less craving; in one older trial in people with alcohol dependence, craving declined gradually over 12 weeks.

Monitoring health while on naltrexone

Your healthcare provider may want to monitor you and your health to ensure that the prescription medication is safe, well-tolerated, and effective, Dr. Clemons says. He says some key parameters to monitor include:

• Liver function tests
• Kidney function tests
• Mental health status
• Opioid use status
• Alcohol consumption status

Always be honest with your doctor so they can help you most effectively and safely. 

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The importance of psychotherapy while on low-dose naltrexone

When you are taking naltrexone for substance use disorder, it’s very important to also engage in psychotherapy, AKA talk therapy. “Treatment is imperative to seek while taking naltrexone to help identify coping skills and underlying challenges to help increase long-term sobriety,” says Lonano. 

Some popular therapy modalities for substance use disorders include:

• Cognitive behavioral therapy (CBT)
• Motivational interviewing (MI)
• Dialectical behavior therapy (DBT)
• Family therapy 

Additionally, peer support groups play an important role in recovery for many people with OUD and AUD. These groups provide a sense of community, solidarity, and accountability. 

• Alcoholics Anonymous (AA)
• Narcotics Anonymous (NA)
• Refuge Recovery
• Yoga 12-step Recovery (Y12SR)
• SMART Recovery

Alternative uses for naltrexone

Outside of use for treating alcohol addiction and unhealthy opioid use, LDN is being researched for other conditions, such as chronic pain conditions and conditions linked to inflammation, including: 

• Fibromyalgia
• Multiple sclerosis (MS) 
• Crohn’s disease
• Complex regional pain syndrome
• Diabetic neuropathy
• Myalgic encephalomyelitis/chronic fatigue syndrome
• Long COVID 

LDN therapy is thought to provide pain relief by reducing inflammation, but the exact mechanism of action for helping these chronic pain conditions is still being studied. 

Ultimately, LDN therapy is not FDA-approved to treat any of these conditions, and more research is needed. However, it is an exciting area of research that shows promise for people struggling with chronic pain and conditions related to inflammation.

Frequently asked questions about low-dose naltrexone

How Charlie Health can help 

If you struggle with alcohol use disorder or opioid use disorder, Charlie Health can help. Our virtual Intensive Outpatient Program (IOP) provides more than once-weekly mental health treatment for people dealing with serious mental health conditions, including substance use disorder and co-occurring disorders, such as anxiety, depression, and more.

Our compassionate clinicians meet you where you are on your recovery journey. We incorporate evidence-based therapies, like CBT, DBT, and motivational interviewing, into individual counseling, family therapy, and group sessions. With this kind of support, recovery is possible. Fill out the form below or give us a call to start your sobriety journey today.