Naltrexone side effects: what to expect
Naltrexone side effects are often nausea, headache, and sleep changes, but rare serious liver injury and opioid withdrawal can occur. Know when to call.
Key facts
- Low-Dose Naltrexone (LDN) is $66.34/month (billed $199 every 90 days), charged only after a clinician approves it.
- Answer a few health questions online. A licensed clinician reviews them. If approved, it ships to your door.
- Adults 18 or older. A licensed clinician reviews your health history and decides whether treatment is appropriate for you. Availability depends on the state you live in.
Naltrexone can cause side effects that range from mild stomach upset to rare but serious problems like liver injury. Your risk depends on your dose, other medicines, alcohol or opioid use, and your underlying health. This guide explains naltrexone side effects to watch for, what is usually temporary, and when you should get medical help. If you want to discuss your own risk factors and medication list, PocketMD in Vitals Vault can help you prepare questions for a clinician visit.
- Naltrexone side effects are often nausea, headache, and sleep changes, especially early on.
- Serious risks include liver injury and sudden opioid withdrawal if opioids are in your system.
- Do not use naltrexone if you currently use opioids or are in acute opioid withdrawal.
- Call a clinician for yellow skin, dark urine, severe abdominal pain, or worsening mood.
Naltrexone side effects, in plain language
Most are manageable
The most common naltrexone side effects involve your stomach, head, and sleep. Many people notice them most when starting or when the dose changes. If side effects are persistent or worsening, a clinician can help you weigh options.
A few are urgent
Rarely, naltrexone can cause serious liver problems or trigger sudden opioid withdrawal if opioids are in your system. These are situations where you should contact a clinician right away or seek urgent care based on severity. Always tell your clinician about any opioid use, including cough or diarrhea medicines that may contain opioids.
Opioids are the key interaction
Naltrexone blocks opioid receptors. If you take opioids while on naltrexone, pain medicines may not work well and trying to override the blockade can be dangerous. Starting naltrexone too soon after opioids can cause abrupt withdrawal.
Common and serious side effects (and what may help)
Nausea or stomach upset
Nausea is one of the most commonly reported side effects. It is often most noticeable early in treatment and may improve as your body adjusts. If you cannot keep fluids down, have severe belly pain, or symptoms are persistent, contact a clinician.
Headache or dizziness
Some people report headache, lightheadedness, or dizziness. These can overlap with dehydration, poor sleep, or alcohol withdrawal in some settings. Seek medical care urgently if you have a sudden severe headache, fainting, weakness on one side, or trouble speaking.
Sleep changes
Trouble sleeping, vivid dreams, or feeling unusually tired can occur. Sleep issues may be more noticeable when starting, during stress, or with other stimulants like caffeine. If sleep problems are severe or come with agitation or mood changes, check in with a clinician.
Anxiety or mood changes
Some people report nervousness, anxiety, or low mood. Because alcohol and opioid use disorders are associated with depression and suicide risk, mood symptoms should be taken seriously. If you have thoughts of self-harm, seek emergency help immediately.
Liver injury (hepatitis)
Naltrexone has been associated with cases of hepatitis and clinically significant liver dysfunction. Contact a clinician promptly if you develop yellowing of the skin or eyes, dark urine, light-colored stools, persistent nausea, or right upper belly pain. Your clinician may check liver tests if symptoms or risk factors are present.
Opioid withdrawal or overdose risk
If you are physically dependent on opioids, naltrexone can precipitate sudden withdrawal. Also, after stopping naltrexone, your opioid tolerance may be lower, increasing overdose risk if you return to opioids. Tell every clinician you see that you take naltrexone, especially before surgery or pain treatment.
- What naltrexone does
- An opioid receptor antagonist that blocks the effects of opioids.
- Key safety theme
- Using opioids while taking naltrexone can be dangerous and may reduce pain control.
- Serious symptom cluster to act on
- Possible liver injury symptoms include jaundice, dark urine, and persistent abdominal pain.
How long do naltrexone side effects last?
Early effects are common
Stomach upset, headache, and sleep changes are often reported early in treatment and may lessen with time. If symptoms are getting worse instead of better, it is a reason to check in. Do not try to “push through” severe symptoms without medical advice.
Serious symptoms are not wait-and-see
Symptoms that could signal liver injury, severe allergic reaction, or severe mood changes should be treated as urgent. If you have yellow skin or eyes, confusion, severe abdominal pain, or thoughts of self-harm, seek immediate medical care. If you may have taken opioids, contact a clinician right away.
Withdrawal can be rapid
If naltrexone is started when opioids are still in your system, withdrawal symptoms can begin quickly and be intense. This is one of the main reasons clinicians confirm you are opioid-free before starting. Always disclose all opioid exposures, including nonprescription products that may contain opioids.
When to call a clinician or seek urgent care
Call urgently for liver symptoms
Contact a clinician promptly for yellow skin or eyes, dark urine, light stools, persistent nausea or vomiting, or right upper abdominal pain. These can be signs of liver injury and should not be ignored. Your clinician may recommend evaluation and lab testing.
Get emergency help for self-harm thoughts
If you have thoughts of harming yourself, feel unsafe, or notice severe mood changes, seek emergency help immediately. This matters even if you think it is related to stress, alcohol, or withdrawal. Tell responders what medications you take, including naltrexone.
Call if opioids were used
If you took any opioid medication or used illicit opioids while on naltrexone, contact a clinician. Opioid effects may be blocked, and trying to overcome the blockade can lead to overdose. You may also need a plan for pain control that does not rely on opioids.
Check in for persistent side effects
If nausea, headaches, dizziness, or sleep problems are persistent, interfere with daily life, or cause you to stop eating or drinking normally, contact your prescriber. A clinician can review timing, other medications, alcohol intake, and medical conditions that may be contributing. Bring a complete medication and supplement list.
Frequently Asked Questions
What are the most common naltrexone side effects?
Commonly reported naltrexone side effects include nausea or stomach upset, headache, dizziness, and sleep changes. Many people notice these most when starting or changing dose. If symptoms are persistent or severe, contact your prescriber.
What are serious side effects of naltrexone?
Serious risks include liver injury and precipitated opioid withdrawal if opioids are in your system. Seek urgent care for jaundice, dark urine, severe abdominal pain, confusion, or thoughts of self-harm. Tell clinicians about any opioid exposure.
Can naltrexone cause liver damage?
Naltrexone has been associated with hepatitis and clinically significant liver dysfunction in some cases. Contact a clinician promptly if you develop yellowing of the skin or eyes, dark urine, or persistent abdominal pain. Your clinician may recommend evaluation and liver tests.
Can you take naltrexone if you use opioids?
No. Naltrexone is contraindicated if you are currently using opioids or are in acute opioid withdrawal. Starting it too soon after opioids can cause sudden, severe withdrawal, so clinicians typically confirm you are opioid-free before treatment.
Are side effects of naltrexone different at low doses?
Lower doses may still cause similar types of side effects, including nausea, headache, and sleep changes. The key safety issues around opioid use and liver symptoms still apply. Discuss your exact dose and formulation with your prescribing clinician.