Separating Myth from Fact: Naltrexone effective time and re-dosing

Recently, there has been a lot of confusion about the effective time period for a standard dose of naltrexone and we want to set the record straight. We’ve noticed an increased amount of misinformation that is not based on the existing body of research or knowledge of this medication. Further clouding the situation, C Three Foundation CEO Claudia Christian accidentally misspoke in an video interview and her words led some to improperly believe (and then assert as fact) that naltrexone is completely flushed from the system after six hours. (It’s not.)

Below is Claudia’s statement, mildly edited for format, structure, and punctuation.

Statement from Claudia Christian:

I’m sorry for any confusion about dosing. I have had many discussions with doctors over the years. Some have stated that a patient has to take a dose of naltrexone every 4 hours, and some have said 8 hours is fine. Dr. Sinclair told me personally that I would be “safe” for 10 hours after taking a 50mg dose. My own doctor advises people to re-dose “as per needed.”

Clearly this has led to some confusion, including my own personal confusion. It’s difficult when you Google it and this comes up for example for the brand Revia:

“REVIA is a pure opioid receptor antagonist. Although well absorbed orally, naltrexone is subject to significant first pass metabolism with oral bio-availability estimates ranging from 5 to 40%. The activity of naltrexone is believed to be due to both parent and the 6­ ß-naltrexol metabolite. Both parent drug and metabolites are excreted primarily by the kidney (53% to 79% of the dose), however, urinary excretion of unchanged naltrexone accounts for less than 2% of an oral dose and fecal excretion is a minor elimination pathway. The mean elimination half-life (T-1/2) values for naltrexone and 6-ß-naltrexol are 4 hours and 13 hours, respectively. Naltrexone and 6-ß-naltrexol are dose proportional in terms of AUC and Cmax over the range of 50 to 200 mg and do not accumulate after 100 mg daily doses.”

Okay…what the heck does that mean in real life terms?

I have noticed that by taking the middle ground and suggesting people talk to their doctor about taking a second dose 6 hours after the first dose, they seem to respond well. Does that mean that the first dose of naltrexone could have protected them for another hour or two or three? I have no idea.

Everyone’s metabolism is different and (their weight, etc.) Certain factors can influence how long naltrexone stays in the system. One is age. Older people tend to take longer to eliminate drugs from their system compared to younger people. A patient’s overall health and any chronic illnesses can also influence how long naltrexone stays in the system. People with a faster metabolism will eliminate naltrexone more quickly than someone with a slower metabolism. Other individual factors that influence how long naltrexone stays in the system can include body mass and hydration level. The average eliminate half-life of naltrexone is between 4 hours and 13 hours.

All of that said and debated comes down to this: What works for you? When you take one dose and have a few drinks? When you take a dose every 8 hours if you’re going to have a weekend that involves both lunch and dinner imbibing? I can’t tell you that.

Your doctor can advise you on what they feel is “right” but at the end of the day it comes down to you to figure out how you metabolize naltrexone, when you “feel” it is out of your system, and when you feel vulnerable to heavy drinking experiences.

I hope this helps clarify the dosage questions and allows you the freedom to customize your own recovery with your doctor’s support. If you feel that a second dose is helping you then you must speak to your doctor to ensure that you have an adequate supply of medication.




  1. Roberta on November 13, 2018 at 8:17 pm

    Dear Claudia,
    You and I have put me on the path of naltrexone.
    Dosing , brand , freqiuency , and expectations are all ambiguous… I am 8 month in…have changed brands from Noctict..( apparent 1 1/2 hour wait)… absolute compliance…to Naltima ( 1 hour wait)…absolute compliance…no effect… or difference…except nodict makes me feel very sick 🤕….and naltima has had no effect…
    I can say my drinking levels have reduced from 10 / day 6/ day….nothing past that..👎😡👩‍💻😡🤔
    I remember the chalk board “ DONT GIVE UP”…
    But…darn it ,,,this disclosure statement has me 😧….worried

  2. Lois Kuiper on November 16, 2018 at 6:47 pm

    I have had gastric bypass.. 14 years out. Lost and kept off over 100 pounds. Started having seizures, 5 in part 6 yes. Taking Keppra for that. Concerned with mal absorption due to bypass. Drink about a bottle of wine nearly daily. 67 years old.

  3. Christy on September 1, 2019 at 8:04 pm

    Claudia can you please answer a quick question for me? I am on day two of taking half of the prescription for Naltrexone, as was directed. I have already noticed a significant change in my desire for eating. I am currently 202 pounds so this is definitely an ok thing at this point! I am just wondering how “normal” this is and what I might be able to expect in the future. Does that taper off as time goes? What is normal? When is there a a reason for concern? With only being at 1/2 dose and feeling this way it makes me wonder. Thank you ever so much! This pill has saved my life.

    • C Three Foundation on September 5, 2019 at 2:23 pm


      Neither Claudia nor myself are doctors, so we cannot give any medial advice. When it comes to side effects, each person is different. The best thing to do is figure out if the side effects are bothersome, or if they last longer than the first 10-14 days (the typical amount of time when most people see side effects fade if they get any at all). At that point, please talk to your doctor. Naltrexone is used in conjunction with Wellbutrin in an FDA-approved weight loss drug, so it’s not really out of the ordinary. Also, as you drink less alcohol, you may find yourself taking in fewer empty calories from the alcohol, which can also assist some people in losing weight.

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