A plain-language guide Unknown harm
What is known about harm?
A short list of reported problems is not a full answer.
Large studies and long studies have not settled how much harm Selank may cause.
FDA says important information about harm in people is missing.
What the maker lists
The maker’s Russian leaflet lists an unpleasant taste and possible allergic reactions.
An allergy is a reaction to a substance.
The leaflet does not say how many people had these problems.
A brief list does not prove that other problems cannot occur.
What FDA is concerned about
FDA warns about a possible immune reaction to Selank.
An immune reaction means the body may treat the substance as an invader.
The warning refers to some ways of giving Selank without naming them. It does not say whether it means nose drops, injections, or both.
FDA is concerned that clumps of Selank or unwanted material mixed with it could trigger that reaction. This warning does not prove that a particular product contains unwanted material.
If a medicine causes a problem
Patients can report suspected medicine problems through MedWatch, FDA’s free reporting service.
A report records what happened, without proving that the medicine was the cause.
Find FDA’s MedWatch service Read about medicine interactionsNotes for this chapter
- FDA: Selank’s concern entry
FDA’s page says its content was current on April 22, 2026. The safety information was checked on September 30, 2026.
The maker’s Russian leaflet
It lists taste and allergy problems, but does not give a full account of possible harm.
- PubMed: a clinical review
The review describes the limited research.
- FDA: limits of problem reports
A report and a proven cause are different things.