They suggest that the safety of over-the-counter medicines should be kept under close review and that patients should be urged to report any adverse reactions.

Medicines are currently divided into classes that do or do not require prescription, write Robin Ferner, Director at the West Midlands Centre for Adverse Drug Reactions and Keith Beard, Consultant Physician at the Victoria Infirmary Glasgow.

Prescription only medicines are subject to a range of controls that are relaxed when medicines are made more freely available over the counter.

When deciding if a medicine should be reclassified to make it available over the counter, regulatory authorities must balance the benefits of easier access against the potential harm from unsupervised or inappropriate use.

Once medicines have been reclassified, they remain subject to safety review.

Patients, doctors and pharmacists can all benefit if medicines are available over the counter. For example, patients can call at a pharmacy any time rather than waiting to see a doctor, general practitioners no longer need to write prescriptions for minor ailments, and pharmacists can make better use of their professional skills.

Drug companies and retail pharmacies can also expect to benefit commercially from reclassification of medicines as over the counter.

However, there are worries about over-the-counter medicines, say the authors. For instance, a patient who makes the wrong diagnosis and uses an inappropriate over-the-counter medicine may present late with a potentially serous but treatable condition. Prescribers also have no opportunity to reinforce instructions for safe use as they can with prescribed medicines.

Regulators can reduce the potential for harm of over-the-counter medicines by specifying the concentration, dose, or pack size that a pharmacist can supply without prescription. However some drugs, such as statins, are probably less effective in low doses than in the higher doses usually prescribed.

Internet shopping now also makes it straightforward, if risky, to order medicines without involving a doctor or pharmacist in the decision. The Royal Pharmaceutical Society of Great Britain estimates that two million Britons obtain their medicines that way.

So what needs to be done to increase the safety of over-the-counter medicines, ask the authors"

The safety of over-the-counter medicines has to be continually reviewed, even though this is difficult in practice, they say. Since healthcare professionals may not be involved, we have to rely on patients to report adverse effects. A new website allowing patients to report adverse drug reactions to the UK Yellow Card scheme could be helpful.

Regulators should also ask for clearer evidence of benefit at the over-the-counter dose if this is lower than the dose usually prescribed, they conclude.

Source: British Medical Journal