Phenibut at a glance: schedule, half-life, and class
- Chemical name
- Beta-phenyl-gamma-aminobutyric acid
- Drug class
- GABA-B receptor agonist (like baclofen); gabapentinoid activity
- US legal status
- Not controlled; not FDA-approved; illegal as a dietary supplement
- Approved elsewhere
- Russia, Latvia (anxiety, insomnia)
- Forms
- Powder, capsules
- Onset
- 2 to 4 hours (slow)
- Duration
- 15 to 24 hours
What is phenibut?
Phenibut was developed in the Soviet Union in the 1960s and is prescribed there for anxiety, insomnia, and other conditions.[1]
In the US it is sold online as a 'nootropic' or sleep and anxiety supplement. The FDA has issued warning letters stating it does not meet the definition of a dietary ingredient.[1]
Phenibut effects and how long they last
Phenibut causes relaxation, reduced anxiety, sociability, and sleepiness. Because it takes hours to work, people often take extra doses before the first takes effect.[1]
Phenibut side effects and risks
Overdose: deep sedation, confusion, and unconsciousness, especially with alcohol or other sedatives.[1]
Dependence: tolerance develops within days to weeks of daily use.[1]
Severe withdrawal: see below; it can resemble alcohol or benzodiazepine withdrawal.
Phenibut interactions: what is dangerous to mix with it
Choose what it would be combined with:
| Combined with | What happens | Guidance |
|---|---|---|
| Alcohol | Deep sedation, vomiting, stopped breathing | Dangerous |
| Benzodiazepines, gabapentinoids, opioids | Profound sedation | Dangerous |
| Baclofen | Additive GABA-B effects | Avoid |
This is not a full list. Combining substances raises the risk of harm, especially when the contents of street drugs are unknown.
Phenibut overdose: signs and what to do
Overdose causes extreme sleepiness, confusion, agitation alternating with stupor, low muscle tone, and coma.[1]
If someone may have overdosed
- Call 911 if the person is unresponsive, hard to wake, or breathing slowly.
- For advice when the person is awake and stable, call Poison Help at 1-800-222-1222 (US, free, 24 hours).
- If opioids could be involved, including pills not from a pharmacy, give naloxone if you have it. Naloxone does not reverse phenibut, but it will not harm the person.
- Stay with the person and place them on their side if they are drowsy or vomiting.
Phenibut withdrawal timeline: symptoms and how long it lasts
People who take phenibut daily can develop strong physical dependence. Withdrawal can be severe and may need hospital care.[1]
- Hours to day 1Symptoms beginRebound anxiety, insomnia, tremor, and irritability.
- Days 1 to 5PeakAgitation, hallucinations, psychosis, and, in severe cases, seizures.
- 1 to 2 weeksResolvesSymptoms ease; anxiety and sleep problems can linger.
Warning: Do not stop daily phenibut suddenly without medical advice. Severe withdrawal can cause psychosis and seizures.
Clinicians often treat phenibut withdrawal with a baclofen taper, sometimes with benzodiazepines.
Is phenibut legal in the US? Schedule and legal status
Phenibut is not a federally controlled substance. It is not an approved drug, and the FDA has said it cannot be sold as a dietary supplement.[1]
- State law: Alabama and some other states have banned it.
Where can someone get help with phenibut use?
- SAMHSA National Helpline: 1-800-662-4357. Free, confidential, 24 hours a day, in English and Spanish. It gives referrals to local treatment and support.[2]
- FindTreatment.gov: a federal locator for state-licensed treatment programs, searchable by location, payment, and type of care.[3]
- 988 Suicide and Crisis Lifeline: call or text 988 for a mental health or substance use crisis.
- Your own clinician: a primary care doctor can screen, treat, and refer, and can discuss medicines that support recovery where they exist.
Phenibut legal status in other countries
| Country | Status |
|---|---|
| Australia | Schedule 9 prohibited substance (since 2018) |
| Russia and Latvia | Prescription medicine |
| International | Not under UN control |
Laws change and differ in detail. Check current rules before carrying any controlled medicine across a border.[4]
Common questions about phenibut
Is phenibut legal?
It is not federally controlled, but it cannot legally be sold as a supplement, and some states ban it.
Is phenibut addictive?
Yes. Daily use can cause dependence and severe withdrawal.
How long does phenibut take to work?
It is slow, often 2 to 4 hours, which leads people to take extra doses.
Is phenibut like gabapentin?
It has some similar activity, but it mainly acts on GABA-B receptors like baclofen.
Can phenibut withdrawal cause seizures?
Yes, in severe cases.
Sources
- Notes from the Field: Phenibut Exposures Reported to Poison Centers, United States, 2009 to 2019. Centers for Disease Control and Prevention, MMWR, 2020.
- National Helpline. Substance Abuse and Mental Health Services Administration.
- FindTreatment.gov. Substance Abuse and Mental Health Services Administration.
- International drug control conventions. United Nations Office on Drugs and Crime.
