Draft guidance / reviewed September 1, 2026
Factual warning language without an invented lethal threshold
No reliable human lethal dose for Phenibut has been established in the available clinical evidence. A label should warn about serious poisoning and provide immediate emergency contacts without implying that any lower quantity is safe.
This is a risk-reduction drafting reference, not certification of a finished label. Final wording must be reconciled with the actual hazard classification, SDS, chemical form, packaging, jurisdiction, and qualified legal and regulatory review.
Recommended full warning panel
WARNING
NO SAFE OR LETHAL HUMAN DOSE HAS BEEN ESTABLISHED FOR PHENIBUT.
Exposure may cause serious poisoning, including severe sedation, loss of consciousness, respiratory depression, coma, or death.
KEEP OUT OF REACH OF CHILDREN.
Do not combine with alcohol or other central nervous system depressants.
IN CASE OF INGESTION OR SUSPECTED POISONING
Call Poison Help: 1-800-222-1222 immediately.
COLLAPSE / SEIZURE / TROUBLE BREATHING / CANNOT BE AWAKENED
Call 911 immediately.
Compact warning for limited label space
No safe or lethal human dose has been established. Serious poisoning may cause respiratory depression, loss of consciousness, coma, or death. Keep out of reach of children.
POISON EXPOSURE: 1-800-222-1222
BREATHING DIFFICULTY / UNCONSCIOUS / SEIZURE: CALL 911
Suspected exposure
Call Poison Help at 1-800-222-1222 in the United States. Poison experts are available 24 hours a day, seven days a week.
Immediate emergency
If the person collapses, has a seizure, has trouble breathing, or cannot be awakened, call 911 immediately.
Why the label should not state a lethal amount
CDC analyzed 1,320 Phenibut exposure reports made to United States poison centers from 2009 through 2019. The report documented severe outcomes but did not establish a human LD50 or a universal quantity above which death can be predicted.
These figures describe poison-center reports, not a controlled dose-response study. Exposure identity was not routinely laboratory-confirmed, and the reports cannot define a safe quantity or predict an individual outcome.
Individual response, co-exposures, product composition, tolerance, health status, and other variables introduce substantial uncertainty. Animal LD50 values, postmortem concentrations, or isolated survival reports should not be converted into a proposed human fatal dose.
A statement such as “10 grams is lethal” is unsupported, while “under 10 grams is safe” could be dangerously misleading. The scientifically supportable statement is that no reliable human safe or lethal threshold has been established.
Regulatory context
FDA states that Phenibut does not meet the statutory definition of a dietary ingredient. In April 2026, FDA again described Phenibut as an unlawful ingredient in dietary supplements in a public alert concerning products marketed as supplements.
This regulatory issue is separate from the design of a toxicity warning. A warning panel does not authorize a product category, establish lawful intended use, or replace the label elements required by an applicable hazard-communication framework.
Label-review checklist
- Confirm that the chemical form, product identifier, CAS number, lot number, and net quantity match controlled records.
- Reconcile every warning with the current SDS and a qualified hazard-classification decision.
- Do not invent a signal word, pictogram, hazard code, precautionary code, assay, or purity statement.
- Support any child-resistant packaging claim with the applicable performance-testing record.
- Confirm responsible-party contact requirements, destination-specific rules, and emergency information.
- Review the website, advertising, social posts, and customer communications for contradictory intended-use evidence.
Primary references
Poison ControlImmediate-assistance guidance and nationwide number (opens in a new tab)
FDAPhenibut in Dietary Supplements (opens in a new tab)
FDA / April 2026Addall product safety alert (opens in a new tab)
Continue with the Phenibut safety and toxicology reference, regulatory and compliance dossier, and Safety Data Sheet guide.
Scope
This page is an educational drafting reference for laboratory-material risk communication. It is not individualized medical advice, legal advice, a hazard classification, or certification that the proposed text satisfies every rule applicable to a finished product.