6 Minutes
You reach for a familiar bottle from the pharmacy shelf and assume safety. After all, it didn’t require a prescription. But ease of access is not the same as harmlessness. What follows is a close look at five widely available over-the-counter medicines whose risks are frequently underestimated — and why that misconception matters in real-world health and public-safety terms.
How everyday remedies can turn problematic
OTC availability creates a comforting illusion: if it’s on the shelf, it must be safe for casual use. That logic ignores how drugs act in the body and how people differ biologically. Consider pharmacogenetics — the study of how genes affect drug response. A single enzyme difference can convert a perfectly standard dose into an unexpectedly dangerous one. That’s not theory. It’s clinical reality.
Codeine-based analgesics illustrate the point sharply. Sold in combination with paracetamol or ibuprofen, codeine is an opioid prodrug; the body metabolises it into morphine to relieve pain. For most people this works as intended. For a subset known as ultra-rapid metabolisers, genetic variants accelerate that conversion, producing higher-than-expected morphine levels. Side effects like drowsiness, nausea and constipation are common. Respiratory depression — slowed breathing — becomes the real danger at higher opioid concentrations.
Tolerance develops with repeated use: the same tablet stops giving the same relief. When people raise doses to chase the original effect, they edge toward physical dependence. Withdrawal can follow abrupt cessation, presenting as anxiety, sweating, restlessness and sleep disturbance. Regulators have tried to curb risk by limiting pack sizes and recommending short-term use; in the UK, for example, non-prescription codeine products are intended for no more than three days. But policy alone cannot replace awareness.
Decongestants, sleeping aids and other hidden risks
Nasal decongestant sprays — xylometazoline and oxymetazoline, for instance — relieve congestion by constricting blood vessels in the nose. Short-term relief is fast and effective. Use them too long and the nose responds with rebound congestion: rhinitis medicamentosa. The drug becomes less effective (tachyphylaxis) and users can become trapped in a cycle of escalating application and worsening symptoms. Long-term overuse can damage nasal tissue, cause nosebleeds, dryness and, in extreme cases, structural harm.
Pseudoephedrine, an oral decongestant, has stimulant properties and appears on lists of substances banned in sport because of that effect. It has also been diverted in illicit methamphetamine manufacture, which is why sales are tightly controlled in many jurisdictions.
Sedating antihistamines — promethazine and diphenhydramine among them — are commonly repurposed as short-term sleep aids. They sedate effectively but tolerance can develop quickly. Rebound insomnia is a frequent complaint when users stop. Promethazine has also been misused recreationally in combinations like “purple drank,” which amplifies sedative and respiratory-depressant effects.
Cough syrups containing dextromethorphan (DXM) are another case. At therapeutic doses, DXM suppresses cough via actions on the brainstem. At higher doses it becomes an NMDA receptor antagonist, producing dissociative effects not unlike low-dose ketamine. That psychoactive potential has made DXM a commonly misused OTC medication in surveillance studies.
Finally, stimulant laxatives are often misunderstood. They work by triggering intestinal muscles to move stool along. Some people misuse them, believing daily bowel movements are mandatory or to manipulate weight. That’s a myth: constipation is usually defined as fewer than three bowel movements per week. Chronic misuse can lead to dehydration, electrolyte disturbances, and damage to the enteric nervous system that impairs natural bowel function. Severe electrolyte imbalance can strain the heart and kidneys.
The common thread through these examples is not intrinsic danger but underestimated risk: biological variability, tolerance, rebound effects and misuse can transform helpful medicines into hazards.
Policy, diagnostics and safer use
Regulators have responded in several ways — limits on pack sizes, clearer labelling, and guidance on short-term use. Still, online purchasing and self-treatment complicate efforts to ensure safe use. Clinical tools like point-of-care pharmacogenetic testing are emerging, but they are not yet routine in community settings. That gap means a person’s genetic predispositions often remain invisible until an adverse reaction occurs.
Health professionals can help by asking simple questions: how long have you been using this medicine, what dose, and for what reason? Those short conversations frequently reveal patterns of overuse or misuse. Public health messaging that explains concepts such as tolerance, dependence and rebound effects in plain language would also reduce harm.
Expert Insight
"Pharmacology is full of nuance," says Dr. Elena Morales, a clinical pharmacologist at the University of Edinburgh. "Two patients given the same OTC pill can have very different outcomes because of genetics, interactions with other drugs, or patterns of use. Our goal should be to make that nuance visible — not to scare people, but to help them use medicines wisely."
Dr. Morales notes that better integration of pharmacogenetic information into prescribing records, more consumer education at the point of sale, and tighter controls on pack sizes where misuse is common are practical steps that can lower risk without removing access.
If one lesson stands out, it is this: over-the-counter does not mean risk-free. Treat common remedies with the same attentiveness you would a prescription drug — read labels, follow duration guidance, and consult a clinician if symptoms persist or you find yourself increasing doses. The small decisions we make at the pharmacy counter can shape health outcomes in ways we rarely anticipate.
Source: sciencealert
Comments
Reza
Is this even true? pack size limits feel a bit nanny state, but if genetics turn codeine into morphine then ok, makes me rethink what I buy over the counter
labcore
Wow didn’t expect OTC stuff to be that risky tbh. My cousin abused cough syrup once, the dissociation was real… scary how normal meds can flip on you
Leave a Comment