Phenibut is a small molecule rather than a peptide. GB-115 is a synthetic dipeptide, cck receptor antagonist.
| Comparison | Phenibut fenibut · beta-phenyl-GABA | GB-115 GB115 · dilept-related dipeptide |
|---|---|---|
| How it works | How it works Phenibut is GABA with a phenyl ring attached, and that ring is what lets it reach the brain. | How it works Most anxiety drugs damp the brain down. This one interferes with a specific panic signal. |
| What it is | A Russian anxiety drug sold as a nootropic. Stopping it suddenly can be dangerous. | A Russian anti-anxiety dipeptide that blocks a panic receptor instead of sedating you. |
| Status | Research onlyApproved abroad, not FDA approved | Research only |
| Typical dose | — | 1 mg per day |
| How often | Not daily, if at all | Daily in the study |
| Stays active | About 5 hours | No verified published figure |
| Dose comes from | No established range | Clinical trial protocol |
| Cycled? | Regular use is the problem, not the solution No established range | 21 days in the one human study Clinical trial protocol |
| What it does | ||
| Drug class | GABA-B agonist (oral, not a peptide) | Synthetic dipeptide, CCK receptor antagonist |
| Used for | A prescription anxiety drug in some countries, sold in the US as a calm-and-focus supplement, with a real dependence problem. | An experimental Russian anti-anxiety compound. A few vendors sell it. One human study backs it. |
| Receptors hit | — | CCK-1, CCK-2 |
| Numbers | ||
| Full dose line | No safe self-directed dose is established | 1 mg per day in the published human study |
| Why that cycle | There is no cycling schedule that makes this safe to take regularly. Tolerance builds fast enough that a routine of any kind tends to escalate. Where it is prescribed, courses are short and supervised. | The published study ran 21 days of continuous dosing. Nothing addresses longer use, breaks, or what happens on stopping. |
| Weight / effect | Not measured in a trial | Not measured in a trial |
| Chain length | Not disclosed | 2 residues |
| Common vial | — | — |
| Before you start | ||
| Route | By mouth (oral) | By mouth (oral) |
| Do not use if | Drinking alcohol, or taking benzodiazepines, opioids or any other sedative, since the effects stack A history of substance dependence of any kind Driving or operating machinery Pregnancy and breastfeeding Stopping suddenly after regular use, which is itself the dangerous part | Pregnancy and breastfeeding Any existing anxiety disorder being treated with prescribed medication, without medical advice Children, who have not been studied |
What separates them
Proof behind the dose. GB-115 has a dose from a clinical trial protocol. Phenibut has no established dose range at all.
What doesn't differ: They are both taken the same way (by mouth) and aimed at the same thing (calm & anxiety). Neither has a measured effect size from a published trial, so there is no number to rank them on.
What people actually report
Phenibut
- Tolerance and physical dependence can develop within weeks, and daily use is the main route to it.
- Stopping abruptly can cause withdrawal severe enough to require hospital care, including hallucinations, agitation and seizures.
- More than 80 cases of coma and death have been associated with phenibut use and withdrawal in the published literature.
- The FDA has stated it does not meet the definition of a dietary ingredient, so any supplement declaring it is misbranded.
- Do not stop suddenly if you have been taking it regularly. Abrupt withdrawal can cause seizures, and tapering needs medical supervision
- Seek urgent care for hallucinations, severe agitation, confusion, or a seizure
GB-115
- The entire human record is one open study in 31 patients over 21 days.
- Almost all the supporting work comes from a single institute, and much of it is published in Russian.
- Blocking cholecystokinin signalling has not been characterised for long-term use in anyone.
- Worsening anxiety, panic or low mood
- Any new or unexplained symptom that starts after beginning it
Side effects are what users and trials report most often, not a complete list. Anything sudden, spreading, or breathing-related is an emergency regardless of which compound caused it.
People also compare
This comparison does not cover cost, long-term safety, or how you personally will respond. Effect figures come from separate trials in different populations and are not always directly comparable to each other. Nothing here is medical advice or a recommendation to use any of these. Talk to a clinician about your own situation.