• Most patients take their naltrexone tablet in the morning, but the manufacturer does not specify a certain time of the day.
• Some patients feel taking naltrexone in the morning after breakfast is a good reminder of their continued treatment commitment for opioid use disorder or alcohol use disorder.
• Taking with food or a meal may help to lower nausea or stomach pain if you experience this side effect.
• If your doctor has advised you to take naltrexone at a certain time of the day or night, follow their instructions instead.
• Naltrexone should only be given as part of a medically-supervised addiction treatment plan.

Naltrexone tablets may cause trouble with sleeping (insomnia) in about 3% (3 out of every 100) people who take it. It has also been reported to cause nervousness (4%) and anxiety (2%). If these are side effects you are experiencing, speak with your doctor to determine if it might be helpful to take your medication in the morning.

Naltrexone may also cause drowsiness, fatigue or dizziness and affect your ability to drive or operate machinery. Do not perform any kind of hazardous task if naltrexone affects you like this.

How long do I use naltrexone?

If you are using naltrexone tablets for alcohol use disorder, your doctor may prescribe this treatment for 12 weeks or longer. Studies conducted by the manufacturer assessed safety and effectiveness up to 12 weeks. Don't take extra pills, skip pills or stop your medication until you talk to your doctor.

Alternative tablet treatment regimens, other than one tablet every day, may be used for maintenance treatment for both alcohol use disorder and opioid use disorder. Follow your doctor’s order for dosing.

If you receive the long-acting intramuscular injection form of naltrexone (brand name: Vivitrol), you will only receive your injection at your doctor’s office once per month. You do not give this medication to yourself. The injection will be shipped directly to your doctor. Do not attempt to give yourself an injection of naltrexone. Injectable naltrexone has been associated with serious injection site reactions and skin reactions.

The length of time you will receive naltrexone treatment is dependent upon your response to treatment and your goals. Many patients receive naltrexone injection for at least one year. Follow your doctor’s instruction for dosing at all times.

Before starting naltrexone, you must be opioid-free for a minimum of 7 to 14 days to avoid sudden opioid withdrawal. Patients who are physically dependent on opiates should complete detoxification prior to initiation of naltrexone therapy.

If you should relapse after a period of opioid abstinence, or stop naltrexone treatment, it is possible that the dosage of opioid that you previously used may have life-threatening consequences, including respiratory arrest (slowed or stopped breathing), circulatory collapse, and death. Do not use opioids (narcotics) with naltrexone.

How long does naltrexone work?

The 50-mg oral tablets have an effect that lasts 24 to 36 hours. Higher doses have a longer duration, with 100 mg lasting 48 hours and 150 mg lasting 72 hours. Oral naltrexone tablets are usually given once a day.

Blood levels of intramuscular naltrexone (brand name: Vivitrol) will begin to slowly decrease 14 days after dosing, but levels will be measurable for about one month.

Does naltrexone make you sleepy?

Dizziness, drowsiness, sedation and fainting have all been reported as possible side effects with naltrexone treatment.

Do not drive, operate heavy machinery or perform any other dangerous activities until you know how naltrexone will affect you.

Naltrexone may cause some patients to feel depressed. Tell your doctor if you have a history of depression, attempted suicide, or other mental health disorders before you start naltrexone treatment. Tell your family members or other people close to you that you are taking naltrexone. They should call a doctor right away if you become depressed or experience symptoms of depression.

Bottom Line

• The manufacturer does not specify if you should take naltrexone tablets in the morning or at night. Take naltrexone exactly as your doctor orders.
• Many patients take their medication in the morning to help affirm their continued treatment success for either opioid use disorder or alcohol use disorder.
• Taking naltrexone tablets with food or after a meal may help to lessen any stomach side effects such as nausea or pain.

This is not all the information you need to know about naltrexone tablets or Vivitrol for safe and effective use. Review the full naltrexone prescribing information here, and discuss this drug with your doctor or other health care provider.