A common family of drugs used to treat rheumatoid arthritis have been linked with skin problems.

Up to a quarter of people taking anti-TNF drugs get skin infections, rashes or eczema, a Dutch study in Arthritis Research and Therapy reveals.

Experts said the benefits of anti-TNF drugs would outweigh any skin risks for most patients using this therapy.

However, other arthritis drugs have had safety concerns, potentially cutting down treatment options for some.

Safety concerns

Last year Merck voluntarily withdrew its blockbuster arthritis drug Vioxx (rofecoxib) from the market after data showed users had a 50% higher chance of a heart attack and sudden cardiac death.

European regulators later warned that other drugs in the same family as Vioxx - the COX-2 inhibitors - might carry a similar risk.

Rheumatoid arthritis patients taking a toxic drug called methotrexate were also warned about 25 deaths and 26 cases of serious harm linked to its use in the last 10 years, largely due to the wrong dose being prescribed.

The current concern stems from a study of 289 patients with rheumatoid arthritis being treated with anti-TNF drugs for one to 10 years.

These drugs work by switching off tumour necrosis factor (TNF), which stimulates cells to produce the inflammation response that leads to pain and swelling of the joints.

Unlike the COX-2 painkillers that merely mask symptoms, anti-TNF drugs work to tackle the cause of the problem and are called disease-modifying drugs for this reason.

Rashes

Seventy-two (25%) of the patients developed a skin problem that led them to visit a skin specialist.

In comparison, only 13% of a similar group of rheumatoid arthritis patients that had not received anti-TNF had visited a dermatologist during the same period of time.

The most frequent skin complaints associated with anti-TNF use were skin infections, eczema and allergic rashes.

For seven of the patients, the skin condition was severe enough that they stopped the drug.

The investigators from Radboud University Nijmegen Medical Centre said their findings showed that skin conditions were "a significant and clinically important problem" in rheumatoid arthritis patients on anti-TNF drugs.

They said that because of the way anti-TNF drugs work, suppressing the immune system, they might make users more susceptible to skin conditions.

They recommended further research.

An adviser to the Arthritis Research Campaign, Madeline Deavy, urged people using these drugs not to be alarmed by the findings.

"It is a relatively small study. These drugs have been used by hundreds of thousands of people without major side-effects.

"These are very powerful drugs and any drug will have some side-effects.

"Most people on anti-TNF therapy have got very serious rheumatoid arthritis. Minor skin problems might not be a bad pay-off for the benefit that they do give."

She said many more people with rheumatoid arthritis might benefit from anti-TNF therapy.

"There is a lot of evidence that if you put people with early rheumatoid arthritis on these drugs they do much better. There's even evidence that if you hit the disease very early on some people go into remission."

The NHS treatment advisory body NICE is currently re-evaluating how widely prescribed these drugs should be.

Arthritis Care echoed these views and added that doctors were compiling a register (The Biologics Register) to get a better picture of the side-effects experienced by patients on anti-TNF treatment.