Arthritis is the UK’s largest cause of physical disability. This chronic condition severely impairs the quality of life of up to nine milion people. It costs the NHS £5.5 billion directly, and the wider economy a further £18 billion in lost working hours. Drugs that can keep its symptoms under control are therefore among the most valuable in existence. They lift patients out of pain and misery, and permit many to resume a normal life.

In recent years, most arthritis patients have turned for relief to Cox-2 inhibitors. This class of painkillers was developed in the 1990s as an alternative to non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, which can cause dangerous stomach ulcers. Last June, 70 per cent of GPs were prescribing Cox-2 inhibitors to new arthritis patients. Since then, however, safety fears have brought the market for these drugs close to collapse.

As the Times reported this week, sales of Cox-2 inhibitors fell by 75 per cent between September and February. Only 7 per cent of GPs now choose the drugs for new patients. The reason is the withdrawl first of Vioxx, Merck’s market leader, and more recently Pfizer’s Bextra, after both were linked to heart attacks and strokes. Hundreds of thousands of users have switched away from these drugs and their cousins, Celebrex and Arcoxia, which remain available. But it is far from clear that their overall health will benefit as a result.

There is no doubting the side-effects that some Cox-2 inhibitors have now been shown to have. A study in the Lancet found that people taking Vioxx had a risk of heart disease 34 per cent higher than patients on NSAIDs. Vioxx has been linked to between 88,000 and 140,000 serious heart conditions in the US since 1999. Bextra can trigger a potentially fatal skin allergy, as well as heart problems. Celebrex can be sold in the US only with a prominent warning about cardiovascular risks.

These are serious hazards, of which patients and doctors need to be fully aware. But it does not follow that Cox-2 inhibitors should be kept out of the pharmacy. As is always the case with drugs, risks must be judged against benefits, and rival treatments against one another. Cox-2 inhibitors — possibly even including Vioxx — will often remain the best option.

For most arthritis sufferers, the choice is not between Cox-2 inhibitors and a comparable substitute with fewer side-effects. The alternative is usually a switch to drugs with considerable risks of their own, or stopping treatment and enduring the pain. Vioxx and Celebrex can be highly effective against the symptoms of arthritis, and older drugs do not always work as well. Ordinary NSAIDS are also responsible for 12,000 hospital admissions and 2,600 deaths annually. They kill as many people as malignant melanoma and cervical cancer put together. As with Cox-2 inhibitors, such risks should not remove them from the medicine cabinet, but they cannot be considered an equivalent or even a safe replacement.

Both the positive and negative effects of drugs have to be weighed up by patients and their doctors, to find the most appropriate choice for their medical circumstances. Too often, however, safety scares are allowed to obscure life-enhancing benefits.

This has already happened with the SSRI class of antidepressants, and with hormone replacement therapy: undue concern about possible hazards has led thousands of patients who would benefit from these treatments to reject them.

Regulators, and the GPs to whom arthritis sufferers turn for advice, must tread carefully with Cox-2 inhibitors if the same story is not to be repeated with another useful medicine.

• Clarification: Vitamins and minerals will still be regulated as foodstuffs under the EU Food Supplements Directive (Junk Medicine, April 9). The measure adds extra controls on their sale.

  Mark Henderson is the Times science correspondent

Explore Health News

• Swine flu

Times Recommends

• Milk: do we need a dairy godmother?
• DIY: the women doing it for themselves
• First double portrait of Princes unveiled