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Naltrexone

Three naltrexone products sit on this shelf: Revia at 50 mg, Mysimba at 90 mg combined with bupropion, and Low Dose Naltrexone Capsules at 1.5 mg. This opioid antagonist is used for alcohol dependence, opioid dependence and, in combination with bupropion, weight management.

Low Dose Naltrexone Capsules

Fibromyalgia

1.5mg

Naltrexone capsules for fibromyalgia and fatigue in multiple sclerosis. This low dose is far below the addiction-treatment amount.

From$2.13/ capsuleView

Mysimba

Chronic Weight Management

90mg + 8mg

Naltrexone and bupropion tablets for weight management. They work on the brain's reward system to cut food cravings.

From$2.89/ tabletView

Revia

Alcohol Dependence, Opioid Dependence

50mg

Naltrexone tablets for alcohol and opioid dependence. They block the reward effects of these substances, reducing craving.

From$3.84/ tabletView

Key points

  • Naltrexone blocks opioid receptors, so starting it while opioids remain in the body can trigger a withdrawal reaction. An opioid-free interval of at least 7 to 10 days is recommended after short-acting opioids, extending to two weeks after buprenorphine or methadone.
  • Mysimba pairs 90 mg naltrexone with 8 mg bupropion in a prolonged-release tablet, indicated for weight management alongside a reduced-calorie diet and increased physical activity.
  • The label warns of hepatitis and liver dysfunction associated with naltrexone exposure; patients should seek medical attention for symptoms of acute hepatitis and stop treatment if they appear.

How does Naltrexone work?

Naltrexone is an opioid antagonist, meaning it binds to opioid receptors in the brain and reversibly blocks the effects of opioids taken from outside the body. A person who takes naltrexone and then uses an opioid will not feel the euphoria or sedation that drug would normally produce.

At 50 mg, Revia occupies enough receptors to block opioid effects for a full day. In Mysimba, the 90 mg naltrexone component works alongside bupropion to support weight management in adults who meet a body-mass-index threshold. At the much lower 1.5 mg dose in Low Dose Naltrexone Capsules, the same receptor-blocking action is listed for Fibromyalgia and Multiple Sclerosis-associated Fatigue.

Brands and forms in this catalogue

Revia is the brand-name 50 mg tablet, listed for alcohol dependence and opioid dependence. Mysimba is a separate brand-name product from Orexigen Therapeutics: a prolonged-release tablet that combines naltrexone with bupropion for chronic weight management. Low Dose Naltrexone Capsules carry just 1.5 mg in a capsule and appear under Pain & Anti-inflammatories for fibromyalgia and MS-associated fatigue.

The two forms matter for how you take the medicine. Revia and Mysimba are tablets; Mysimba’s prolonged-release design means the naltrexone and bupropion are released slowly over hours rather than all at once. The capsule form of Low Dose Naltrexone Capsules delivers a fraction of the dose found in Revia, which is why it sits in a different category and serves a different purpose on the shelf.

Further reading

What is naltrexone used for?

Naltrexone is used for alcohol dependence and opioid dependence. In combination with bupropion it is used for weight management, and the low-dose capsule form is used for fibromyalgia and multiple sclerosis-associated fatigue.

What does naltrexone do in the body?

Naltrexone is an opioid antagonist, so it binds to opioid receptors in the brain and reversibly blocks the effects of opioids taken from outside the body.

Can naltrexone be taken with opioid pain medicines?

Naltrexone interacts with opioid analgesics. Because it blocks opioid receptors, starting it while opioids remain in the body can trigger a withdrawal reaction. Speak to your doctor or pharmacist before combining them.

How long does naltrexone take to work?

Naltrexone usually takes 1 to 2 weeks to show its full effect.

What side effects can naltrexone cause?

Common side effects include headache, nausea and vivid dreams. Insomnia, mild anxiety and fatigue can also occur, and severe liver damage (hepatotoxicity) requires immediate medical attention. Speak to your doctor or pharmacist if you are concerned.

In which products can I find naltrexone?

On Direct Meds, naltrexone comes as Low Dose Naltrexone Capsules, Revia and Mysimba. Compare their forms, strengths and packs.

How is naltrexone priced?

Compare the rand prices for each product, strength and pack above. Prices are converted from US dollars.

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Can I buy naltrexone over the counter in South Africa?

Yes, online. Direct Meds does not ask for a prescription to order naltrexone. We are a broker, not a dispensing pharmacy. We arrange orders and delivery with our affiliated supplier on your behalf.

Ordering without a prescription →

Where can I buy naltrexone in South Africa?

On Direct Meds: choose the product, strength and pack, then check out. Our affiliated supplier delivers across South Africa. Estimated delivery is 7 days with Express Delivery, which includes online tracking, or up to 3 weeks with Regular Delivery.

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