Clinical Information
Use this medicine exactly as your healthcare provider tells you. Swallow the tablet with water at about the same time each day unless told otherwise. If you miss a dose, take it as soon as you remember unless it is almost time for your next dose. Do not take two doses at the same time. Your healthcare provider will decide how long you should stay on treatment.
Naltrexone attaches to opioid receptors for a short time and blocks them. This short block causes your body to rebound and release more of its own natural endorphins after the medicine wears off. Endorphins can improve mood, lower pain signals, and may help control appetite and inflammation. Most people begin to notice benefits within 4–8 weeks, but full effects may take 2–3 months of regular use. Each dose works for about 6–8 hours in the body, yet the endorphin boost can last longer.
Do not use if you are currently taking opioid pain medicines, using opioid street drugs, or are in opioid withdrawal (can cause severe withdrawal symptoms). Do not use if you are allergic to naltrexone or any tablet ingredients. Avoid use if you have acute hepatitis or severe liver failure, as the medicine can stress the liver. Do not use if you are pregnant or breastfeeding unless your provider decides the benefits outweigh the risks. Not for children under 18 unless specifically prescribed by a pediatric specialist.
Serious interaction with all opioid medicines (such as oxycodone, hydrocodone, morphine, codeine cough syrup); do not mix—can cause sudden withdrawal or block pain relief. May lessen the effect of opioid-based diarrhea or cough treatments. Use caution with liver-affecting drugs like isoniazid, methotrexate, acetaminophen over 4,000 mg per day, and some antifungals (ketoconazole) because of added liver stress. Tell your provider if you take warfarin (Coumadin), thioridazine, bupropion, or herbal supplements like kava or valerian, which can raise dizziness or liver side-effect risk. Limit alcohol; heavy drinking increases liver strain.
Very common (more than 1 in 10 people): trouble sleeping, vivid dreams. Common (1–10 in 100 people): nausea, stomach cramps, headache, mild anxiety, tiredness. Uncommon (1–10 in 1,000 people): joint pain, increased heart rate, mild increases in liver enzymes. Rare but serious: severe liver problems (yellow skin or eyes, dark urine), severe allergic reaction (rash, swelling of face or throat). Most mild side effects improve within 1–2 weeks. Contact your provider if side effects are severe, last more than two weeks, or if you notice signs of liver trouble.
Store at controlled room temperature 68–77 °F (20–25 °C) in the original, tightly closed bottle. Keep away from moisture, heat, and direct sunlight. Do not store in bathrooms or near kitchen sinks. Keep out of reach of children and pets. Do not use tablets past the expiration date printed on the label. Return unused or expired tablets to a pharmacy take-back program or mix with used coffee grounds in a sealed plastic bag before throwing in household trash if no take-back is available.
Frequently Asked Questions
Q:Can I take pain medicine while on low-dose naltrexone?
A:Do not use any opioid pain medicines (like oxycodone, hydrocodone, or codeine) while taking naltrexone because the tablets block their effect and can cause sudden withdrawal. Non-opioid pain relievers such as acetaminophen or ibuprofen are usually safe, but check with your provider first.
Q:What should I do if I need surgery or emergency pain control?
A:Tell all healthcare workers you take naltrexone. Your surgeon or ER doctor may ask you to stop naltrexone 48–72 hours before planned surgery so opioid pain medicine can work. Never stop on your own without medical advice.
Q:Is this medicine safe for people with liver issues?
A:Naltrexone is processed by the liver, so people with active hepatitis or severe liver disease should not use it. If you have any liver history, your provider will check blood tests before and during treatment.
Q:Can I drink alcohol while taking low-dose naltrexone?
A:Small social amounts are not likely to cause problems, but heavy drinking puts extra strain on your liver while using this medicine. Limit alcohol and talk with your provider if you drink more than a few drinks per week.
Q:What happens if I stop the tablets suddenly?
A:Stopping low-dose naltrexone does not cause withdrawal, but your symptoms may return. Let your provider know before stopping so they can plan the next steps in your treatment.
Q:How should I store the tablets when traveling?
A:Keep them in their original bottle, inside a cool, dry bag. Avoid leaving them in a hot car or direct sunlight. If flying, carry them in your hand luggage to prevent extreme temperature changes.
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