Can bath oils help treat atopic eczema?

The effectiveness of rash emollients has come into question, writes Rachel Liddle.

What do the papers say?
NHS funding is being wasted on eczema-easing bath oils that are of 'questionable' value, the media reported last week.

The products are prescribed to ease the skin inflammation caused by allergic eczema, but there is no clinical evidence they work, according to researchers in the Drugs and Therapeutics Bulletin (DTB).

The NHS spends £16 million a year on bath oils, about 70p per bath, say the papers. Bath emollients are thought to be easier to apply than topical treatments and are believed to form a protective barrier against irritants.

There is no evidence to back this up and emollients could even cause problems, such as slipping in the bath, say media reports.

What is the research?
The story stems from a discussion piece in the DTB which examines the evidence and use of both bath and topical emollients.

The article seems to have been inspired by issues of cost. Each year the NHS spends more than £16 million pounds on bath emollients; 38 per cent of the total cost of treatments prescribed for preschool children with eczema.

Sixteen bath emollients are available on the NHS, costing from 1p to 74p per bath. The main ingredient is liquid paraffin mixed with another emollient such as wool fat or isopropyl mystristate. Lauromacrogols are also added to some bath oils to prevent itching.

These preparations are intended as a replacement for soap and detergents, which can be irritants to atopic eczema.

Adding the emollient to the bath is believed to be an easier way of applying it to the whole body and can help to prevent moisture loss from the skin.

Three bath emollients contain antimicrobials and are marketed as prophylactic treatment for eczema at risk of infection or to help treat secondary infection.

But there is no published evidence from randomised controlled clinical trials that both emollients help atopic eczema, says the DTB.

Neither is there significant evidence that applying emollient ointments, creams and lotions are of benefit.

But the DTB says there is a consensus among clinicians that topical treatments are effective.

What do the authors say?
Andrea Tarr, DTB associate editor, said the article had been compiled with expert input from clinicians, GPs and the pharmaceutical industry.

'We're saying we don't know bath oils' effectiveness,' she said.

'There's an assumption that they are effective because they are being very widely used.'

Trials comparing a bath in water alone followed by topical emollients and using bath emollients then topical emollients is needed, said Ms Tarr.

'Sometimes the idea of using oils is still bound up with the idea of complete emollient therapy.'

But GPs should think about whether patients need bath emollients as well as topical emollients, she added.

What do the experts say?
Use of bath emollients for atopic eczema was advocated by the Primary Care Dermatology Society (PCDS) and British Association of Dermatologists (BAD) in a joint guideline issued last month.

Stephen Jones, consultant dermatologist at Wirral University Hospital and honorary secretary of BAD, said: 'There have been few trials of moisturisers alone but such trials would be difficult to complete.

'The lack of such trials does not mean a lack of any benefit,' he added. 'They are a tried-and-tested part of the treatment of eczema and are accepted as part of routine practice.'

Dr Stephen Hayes, a dermatology GPSI in Southampton and committee member of the PCDS, said claims bath emollients may not be effective are 'rubbish'.

'It's universally agreed among primary and secondary care dermatology doctors that emollients are underutilised.'

When patients present with atopic eczema, GPs should first ensure any irritants are identified to stop making the condition worse. Then emollients need to be prescribed, he added.

However, it will take trial and error to decide which emollients are best for individual patients.

'Any restrictions on using emollients are wrong and we will resist them,' said Dr Hayes.

INFORMING PATIENTS
  • Patients with dermatological conditions should be prescribed a range of emollients.
    There is little clinical trial evidence to support the effectiveness of emollients.
  • Clinicians have seen the value of emollients in practice.
  • Bath oils are one of a number of emollients that can be offered to patients.

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