Naltrexone

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: May 21, 2024

Warnings

Naltrexone Warnings, Risks, and Complications

Naltrexone can cause or worsen health problems in some people. Talk to your doctor about other treatment options for opioid or alcohol dependence if you are at a high risk of complications from naltrexone treatment. Some of the risks of naltrexone use include:

RISK OF OPIOID OVERDOSE: Taking naltrexone makes the body more sensitive to opioids. If you take opioids (even at low doses or previously tolerated doses) while on naltrexone, it can result in opioid intoxication and overdose. Call your doctor without delay if you develop signs and symptoms of an opioid overdose, such as cold and clammy skin, drowsiness, dizziness, and slowed breathing. Talk to your doctor about having the rescue medication naloxone available for emergency treatment of an opioid overdose.
OPIOID WITHDRAWAL SYMPTOMS: If someone with a physical dependence on opioids takes naltrexone, it can precipitate withdrawal symptoms. To prevent this, an opioid-free period of 7-14 days is recommended before starting treatment with naltrexone. Your doctor may give you a naloxone challenge test before prescribing naltrexone. If you need to receive pain management in an emergency situation, your healthcare providers will use regional anesthesia or non-opioid pain medications or give you opioid pain medications under close medical supervision.
ACUTE HEPATITIS: There are reports of liver dysfunction and acute hepatitis in people taking naltrexone. Tell your doctor if you have a history of liver problems before starting treatment with this drug. Call your doctor right away if you develop signs and symptoms of acute hepatitis, such as fever, lack of energy, tiredness, loss of appetite, nausea, vomiting, diarrhea, and stomach pain.
EOSINOPHILIC PNEUMONIA: Rarely, taking naltrexone can lead to a condition called eosinophilic pneumonia. Call your doctor without delay if you develop chest pain, shortness of breath, or difficulty breathing while on this medicine.
DEPRESSION AND SUICIDAL IDEATION: People in recovery from opioid or alcohol dependence, including those taking naltrexone, can develop depression and suicidal thinking. Call your doctor if you or your family notice any unusual changes in mood or behavior or if you have thoughts of harming yourself.
SERIOUS ALLERGIC REACTIONS: In a small number of people, naltrexone can cause serious allergic reactions, including anaphylaxis (throat closing). Call your doctor immediately or seek emergency medical care if you develop a skin rash, hives, itching, swelling of the head and neck, hoarseness, wheezing, or difficulty breathing or swallowing.

Precautions Before Starting Naltrexone

Tell your doctor if you have had an allergic reaction to naltrexone, any of the active or inactive ingredients in naltrexone formulations, other opioids, or any other medications. Your pharmacy can give you a list of ingredients.

Give your doctor or pharmacist a complete list of your medications, including prescription medications, non-prescription medicines, vitamins, dietary supplements, and herbal products. This can help avoid possible interactions between naltrexone and your other medicines.

You should not take naltrexone if you are taking or have taken within the last 7-10 days any prescription opioid drugs, street drugs, or certain medications used to treat cough, pain, or diarrhea.

Give your doctor a complete medical history. Naltrexone may not be safe for people with certain health conditions, such as depression, liver disease, or kidney disease.

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy, or are breastfeeding.

Precautions During Use of Naltrexone

Keep all your healthcare appointments while on this medication. Naltrexone patients are at risk of serious injury to the liver, and your doctor may want to order liver function tests during treatment with naltrexone.

Do not drink alcohol, take any prescription opioid medications, or use opioid street drugs while you are on naltrexone. You may not feel the effects of these substances at low or previously tolerated doses. Higher doses of opioids during naltrexone treatment can cause serious health complications, including coma and death.

Tell all your doctors that you are on naltrexone before any surgery, including dental procedures. Tell all laboratory personnel that you are on naltrexone, as this drug can interfere with the results of certain tests. Carry a medical information card or wear a bracelet that tells healthcare providers that you are on naltrexone in emergency situations so that they don’t give you opioid drugs. After finishing treatment with naltrexone, tell your doctors that you previously took this medicine.

Tell your doctor if you become pregnant while on naltrexone.

People who are recovering from drug or alcohol use disorder can develop depression and suicidal thinking during recovery. Call your doctor immediately if you notice any unusual changes in mood or behavior or have thoughts of harming yourself. Your family should know when and how to seek help if you are unable to do so yourself.

Naltrexone Drug Interactions

Taking naltrexone with certain other drugs can affect how the medicines work. Possible drug interactions between naltrexone and other medicines can increase the risk of severe adverse events. Your doctor may prescribe a lower dose, switch you to other medicines, or monitor you carefully for side effects if there are known interactions between naltrexone and your other medicines. The following medications can have interactions with naltrexone:

Disulfiram (Antabuse)
Thioridazine
Certain medications used to treat cough, diarrhea, and pain

The above list may not include all the possible interactions of naltrexone. Give your doctor or pharmacist a complete list of your medications, including prescription medications, over-the-counter medicines, dietary supplements, and herbal remedies. Also, tell your healthcare provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription and non-prescription medicines.

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