Over the Counter Medication Abuse: What the UK Pharmacy Shelf Actually Carries

“Over the counter” describes how a medicine is sold. It says nothing about what that medicine does once it is inside you. Several products sold in a UK pharmacy without a prescription carry a regulator-mandated addiction warning on the front of the pack, and one of them has been linked to fatal disturbances of heart rhythm.

This page names the groups where the risk is genuine and quotes the UK labels and regulators on each. It does not tell you what to take, how much, or how any of it is misused, for reasons set out near the end.

Sold without a prescription is a legal category, not a safety rating

UK medicines sit in three legal classes. MHRA guidance says pharmacy medicines can be bought “but only from a pharmacy and in the presence of a pharmacist”, while general sale list medicines can be bought “from retail outlets such as corner shops and supermarkets”. Prescription only medicines require a valid prescription from an authorised health professional.

People say “over the counter” for both, which flattens a real distinction. Our observation is that the products with the most misuse potential tend to sit behind the counter, and the pharmacist beside them is the safety feature rather than an inconvenience.

The groups that keep coming up

A 2013 review by Richard Cooper at the University of Sheffield searched international literature from 1990 to 2011 and found over-the-counter medicine abuse in many countries, in five product groups: “codeine-based (especially compound analgesic) medicines, cough products (particularly dextromethorphan), sedative antihistamines, decongestants and laxatives”.

A 2021 systematic review of 53 studies named much the same list. Its pooled prevalence was 16.2% for misuse, 2.0% for abuse and 7.2% for dependence, drawn from only 14 of those studies, with the three terms not defined identically across the literature and the authors stating that “inconsistency was shown across the results of the included studies due to lack of standardisation”.

Laxatives are Cooper’s fifth group and are not covered here, because that harm pattern belongs with eating disorders. Loperamide takes their place.

Codeine is the one that is genuinely addictive

The largest dependence risk on a UK pharmacy shelf is codeine bought inside something else. The NHS describes co-codamol as “a mixture of 2 different painkillers, paracetamol and codeine” and notes that “you can buy the lowest strength from pharmacies but the higher strengths are only available on prescription”. The same applies to codeine combined with ibuprofen. Someone can buy an opioid, take it for a fortnight, and never handle a box they think of as one.

MHRA guidance on over-the-counter painkillers containing codeine or dihydrocodeine restricted the indication to “short term treatment of acute, moderate pain which is not relieved by paracetamol, ibuprofen or aspirin alone”, removed the “colds, flu, coughs and sore throats” indications, capped pack sizes, and required a front-of-pack warning beginning “Can cause addiction”. A day limit follows on the pack, which we do not print, because this page publishes no durations or maximums.

The licensed product information goes further than the pack does. The Nurofen Plus Summary of Product Characteristics states that “tolerance, physical and psychological dependence, and opioid use disorder (OUD) may develop upon repeated administration of opioids such as Nurofen Plus”, and that “repeated use of Nurofen Plus can lead to OUD”. It then records something few expect of a pharmacy painkiller: “serious clinical outcomes, including fatalities, have been reported in association with abuse and dependence with codeine/ibuprofen combinations, particularly when taken for prolonged periods at higher than recommended doses”, naming gastrointestinal perforations, gastrointestinal haemorrhages, severe anaemia, renal failure, renal tubular acidosis and severe hypokalaemia from the ibuprofen component.

That is the point. The opioid half creates the dependence, and the half nobody worries about does much of the damage.

The shelf itself changes when misuse is documented. In February 2024 the MHRA reclassified codeine linctus to a prescription only medicine “owing to the risk of dependence, addiction, and overdose”, having found it “is being used recreationally for its opioid effects”.

We have written separately on codeine and alcohol, whether naproxen is addictive, paracetamol and Percocet.

Sedating antihistamines, and the sleep that never gets fixed

Promethazine and diphenhydramine are sold as allergy medicines and as sleep aids. The NHS says of promethazine that “it’s unlikely that you’ll get addicted”, and then, in the same set of questions, that “if you’ve taken promethazine for a long time and suddenly stop taking it, it’s possible you might feel dizzy, sweaty or sick, have a racing heart and have trouble sleeping”.

Our reading is that they describe two different things: addiction, the compulsive drug-seeking of the kind opioids produce, which the NHS says is unlikely, and physiological dependence, a body that has adjusted to a nightly sedative and objects when it goes.

The diphenhydramine Summary of Product Characteristics is blunter: “tolerance may develop with continuous use”, and “seek medical advice if sleeplessness persists, as insomnia may be a symptom of a serious underlying medical illness”. Escalating use of a sedating antihistamine for sleep is two problems, and only one of them is the tablet.

Cough medicine containing dextromethorphan

The warnings here are stronger than the aisle suggests. UK product information for dextromethorphan cough preparations carries a dedicated subsection on drug dependence, tolerance and potential for abuse. The Robitussin Dry Cough label states that “for all patients, prolonged use of this product may lead to drug dependence (addiction), even at therapeutic doses”, flags particular caution for adolescents, young adults and people with a history of drug abuse, and describes a withdrawal syndrome “characterised by some or all of the following: restlessness, lacrimation, rhinorrhoea, yawning, perspiration, chills, myalgia, mydriasis and palpitations”.

A 2025 systematic review in Current Neuropharmacology analysed 46 studies and reported that antihistamines, dextromethorphan and other over-the-counter drugs can induce psychotic symptoms when misused, dextromethorphan “particularly associated with a chronic tendency towards psychosis”. That literature leans on case reports, so it shows the effect happens rather than how often.

Loperamide, which is not a psychoactive medicine until it is

Loperamide is an anti-diarrhoeal. At recommended doses it acts on the gut, and that is all it is. Its label nonetheless says “caution is needed in patients with a history of drug abuse”, because “abuse and misuse of loperamide, has been described”.

What matters is the extreme. At high doses, in misuse or overdose, loperamide can cause toxicity in the central nervous system and the heart. The Imodium Classic label records that in people who have taken overdoses, “cardiac events such as QT interval and QRS complex prolongation, torsades de pointes, other serious ventricular arrhythmias, cardiac arrest and syncope have been observed”, and that “upon cessation, cases of drug withdrawal syndrome have been observed in individuals abusing, misusing, or intentionally overdosing”. The MHRA reported the same in 2017, naming “serious cardiovascular events (such as QT prolongation, torsades de pointes, and cardiac arrest), including fatalities” in association with large overdoses. No amount appears in that paragraph, which is a decision rather than an oversight.

Decongestants, and a control that is not about you

Pseudoephedrine is here for a different reason. The MHRA restricted its sale between 2007 and 2008 “because of concerns that medicines containing these active substances could be used in the illicit manufacture of the class A controlled drug methylamphetamine”, and requires that supply “must be made by a pharmacist or suitably trained pharmacy staff under the supervision of a pharmacist”. Its position is that “the evidence suggests that the restrictions are successfully continuing to manage the risk of misuse”.

So the questions you get buying a decongestant are mostly about what the product could become, not what it will do to you. Cooper’s review does list decongestants among the groups misused in their own right. Separately, and unrelated to misuse, a 2023 MHRA review examined “the very rare risk of posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction syndrome (RCVS)”. The MHRA concluded that review in 2024 and recognised PRES and RCVS as very rare side effects of pseudoephedrine. We name it so this is not read as an all-clear.

The trap that catches people who never misused anything

Medication overuse headache is the mechanism that pulls careful people into this subject. Take painkillers frequently enough for headaches and the painkillers can begin causing the headaches, producing the pattern that looks like addiction from outside: more tablets, less relief, a strong reaction to stopping.

UK labelling treats this as foreseeable rather than exotic. Codeine and ibuprofen packs carry the statement that if the medicine is taken for headaches beyond a short period “it can make them worse”, and the MHRA’s over-the-counter codeine guidance names overuse headache alongside addiction as a consequence of continuous use.

We do not publish the diagnostic frequency thresholds, which come from the International Headache Society and NICE. Our reading is that printing them here invites readers to audit themselves against a number instead of talking to a GP. Our page on naproxen covers the diagnosis at length, and where heavy drinking is also present, alcohol withdrawal causes headaches in its own right.

What this page refuses to do

There is no checklist here you can pass. We have not written one, because a self-test with a reassuring branch is the most dangerous thing a page like this could publish, and because dependence on a pharmacy medicine is the kind people talk themselves out of. Cooper’s 2013 interview study of 25 UK adults who called themselves addicted to over-the-counter medicines found that most had begun taking them for a legitimate medical reason, remained socially and economically functional, and found standard drug services unsuitable.

Two things are worth saying to a pharmacist or GP whatever you conclude: the real number of days a week you take something, and what happens when you stop. Do not stop a medicine you have taken daily for a long time on the strength of a web page. Opioid withdrawal should be planned, and stopping heavy daily drinking abruptly can be dangerous. If someone cannot be roused, or has taken a large overdose of anything named here, call 999. Outside the UK, use your local emergency number.

Talking to us

The Orchid Recovery is a residential addiction and mental health treatment centre in Hang Dong District, Chiang Mai, Thailand, for international English speaking adults. If a medicine bought at a counter has become something you organise your week around, our pages on prescription drug addiction treatment and opioid addiction treatment explain what residential treatment involves, with supervised detox where it is clinically needed, and polysubstance use is the more relevant read where more than one substance is involved. Our clinical team is listed here, and you can speak to us if it would help. Most people reading this need a pharmacist rather than a residential programme, which is the right outcome.

Sources

• MHRA, Medicines: reclassify your product
• MHRA Drug Safety Update, Over-the-counter painkillers containing codeine or dihydrocodeine
• MHRA Drug Safety Update, Codeine linctus: reclassification to prescription-only medicine, 20 February 2024
• MHRA Drug Safety Update, Loperamide (Imodium): reports of serious cardiac adverse reactions with high doses of loperamide associated with abuse or misuse, 26 September 2017
• MHRA Drug Safety Update, Pseudoephedrine and ephedrine: regular review of minimising risk of misuse in the UK
• MHRA, Safety review of medicines containing pseudoephedrine, 23 February 2023
• NHS, About co-codamol for adults
• NHS, Common questions about promethazine
• NHS, About diphenhydramine
• electronic Medicines Compendium, Nurofen Plus, Summary of Product Characteristics
• electronic Medicines Compendium, Diphenhydramine Hydrochloride 50 mg Tablets, Summary of Product Characteristics
• electronic Medicines Compendium, Robitussin Dry Cough Medicine, Summary of Product Characteristics
• electronic Medicines Compendium, Imodium Classic 2 mg Capsules, Summary of Product Characteristics
• Cooper RJ, Over-the-counter medicine abuse: a review of the literature, Journal of Substance Use 2013;18(2):82-107
• Cooper RJ, ‘I can’t be an addict. I am.’ Over-the-counter medicine abuse: a qualitative study, BMJ Open 2013;3(6):e002913
• Algarni M et al, A mixed-methods systematic review of the prevalence, reasons, associated harms and risk-reduction interventions of over-the-counter (OTC) medicines misuse, abuse and dependence in adults, Journal of Pharmaceutical Policy and Practice 2021
• Mosca A et al, Over-the-counter Psychosis: A Systematic Review of the Misuse of Antihistamines, Cough Medicines, and Decongestants and the Risk of Developing Psychosis, Current Neuropharmacology 2025;23(8):956-973