The FDA says phenibut is not a dietary ingredient, so supplements that list it are misbranded
The FDA says phenibut does not meet the legal definition of a dietary ingredient, so any supplement listing it is misbranded. In April 2019 it sent warning letters to three companies selling phenibut products.
We have not finished checking this source. No judgement either way. how we score evidence
Caveat on this rating: A legal classification, not an assessment of benefit or harm.
Where phenibut stands under US law, in the FDA's own words, because it is sold online as a supplement for sleep and anxiety.
Significant findings
The FDA's page on phenibut in dietary supplements states: "Phenibut is a substance that does not meet the statutory definition of a dietary ingredient." The Food, Drug, and Cosmetic Act defines a dietary ingredient as a vitamin, mineral, herb or other botanical, amino acid, dietary substance, or a concentrate, metabolite, constituent, extract or combination of these. "Because phenibut does not fit any of the categories of dietary ingredients under the FD&C Act, any dietary supplements that declare phenibut as a dietary ingredient are misbranded." The page lists its other names, including fenibut, phenigam, PhGaba, Phenibut HCl and beta-phenyl-GABA.
The FDA's constituent update of 16 April 2019 reported that on 10 April 2019 it issued warning letters to three companies whose products were marketed as dietary supplements and labeled to contain phenibut, noting that phenibut "has been found in products labeled as dietary supplements, sometimes marketed for uses such as a sleep aid." The page also records a 2023 federal court injunction against a seller of a phenibut beverage powder labelled with claims to treat insomnia, alcoholism, PTSD and anxiety.
The other direction
The FDA's position is legal, not a finding about effects: the page does not assess phenibut's benefits or harms. Phenibut is a prescription medicine in Russia and some neighbouring countries, which is how it reached the supplement market. The page invites anyone with evidence that calls the FDA's view into question to submit it.
What this does not show
It does not say what phenibut does, for good or ill; the clinical and poison-centre evidence is in other library rows. It is not advice to start or stop anything. Stopping regular phenibut use can bring withdrawal, which is a reason to plan any change with a clinician.
Worth asking
If I have been taking phenibut regularly, how would a clinician help me stop safely?
Source
Phenibut in Dietary Supplements — US Food and Drug Administration (2023)
Regulator or national health body
How this was scored
- Study design
- Regulatory safety determination
- Funding
- not recorded
- Published in
- Regulator or national health body
- Sample size
- not recorded
- Preregistered
- not recorded
- Conflicts disclosed
- not recorded
- Independent of proponent
- not recorded
- Retracted
- No
We have not finished checking this source, so there is no scoring to show yet. “We have not checked this yet” and “this is disputed” are different statements, so no scored band is shown rather than a low one.
Read the full scoring rubric, including what it can't tell you.
Published October 21, 2026.
Questions
How strong is the evidence behind this?
veisund rates this source "not yet assessed". We have not finished checking this source. No judgement either way. One caveat travels with that badge: A legal classification, not an assessment of benefit or harm. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Phenibut in Dietary Supplements — US Food and Drug Administration (2023). Published in: Regulator or national health body. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Regulatory safety determination. Funding: not recorded. Independence from the proponent is not recorded. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is phenibut, noofen, anvifen, fenibut, phenygam FDA approved for this use?
No. No FDA review of this evidence for this use has taken place.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.