Background::The widespread availability and accessibility of over-the-counter (OTC)
medicines play a vital role in modern healthcare systems, enabling individuals to manage minor
health concerns independently. However, certain OTC medications possess pharmacological properties
that render them susceptible to misuse and abuse, including stimulants, laxatives, sedatives, and
opiate-containing products. Misuse involves improper dosage, duration, or indication, while abuse
entails non-therapeutic use to achieve psychoactive effects or other illicit purposes, potentially leading
to dependence and addiction. This review explores the risk of developing psychotic symptoms
associated with OTC drug misuse. Synthesizing existing literature, it comprehensively examines the
relationship between antihistamines, cough medicines, and decongestants misuse, and the onset of
psychotic symptoms.
Methods::A systematic literature review was carried out using Pubmed, Scopus and Web of Science
databases through the following search strategy: (“diphenhydramine” OR “promethazine” OR
“chlorpheniramine” OR “dimenhydrinate” OR “dextromethorphan” OR “pseudoephedrine” OR codeine-
based cough medicines) AND (“abuse” OR “misuse” OR “craving” OR “addiction”) NOT review
NOT (animal OR rat OR mouse). For data gathering purposes, the Preferred Reporting Items
for Systematic Reviews and Meta-Analyses (PRISMA) was followed. Research methods were registered
on PROSPERO (CRD42024527558).
Results::We analysed 46 relevant studies out of an initial pool of 2,677 articles. Key findings indicate
that antihistamines, dextromethorphan, and other OTC drugs can induce psychotic symptoms,
such as paranoia, hallucinations, and thought disorders when abused. Dextromethorphan is particularly
associated with a chronic tendency towards psychosis, whereas other substances more commonly
result in acute substance-induced psychosis.
Conclusion::The study underscores the necessity for increased awareness and specific interventions
to address the misuse of OTC drugs and their potential to cause significant psychiatric disorders, emphasizing
the broader public health implications of such misuse.