A respected scientific group has recommended not using paracetamol and several other drugs to reduce flu-related fever, saying they may increase the risk of death.

The position of the Wellington-based Medical Research Institute contradicts the established advice of the Ministry of Health and the World Health Organisation to use drugs such as paracetamol and ibuprofen to lower a high temperature caused by influenza. Aspirin should not be given to children or teenagers with viral infections.

However, the ministry said last night it expected to change its recommendations following a review.

A high fever makes the sufferer feel terrible, but the institute, led by respiratory physician Professor Richard Beasley, says there is strong evidence the high temperature that can be caused by influenza helps the body to control the virus.

In a letter published in the New Zealand Medical Journal, Professor Beasley and colleagues say there is insufficient evidence to support the use of the fever-reducing "antipyretic" medicines to treat fever from influenza.

"The limited evidence that does exist [from animal studies] suggests that the administration of antipyretics may have the potential to increase the severity of influenza illness and the risk of mortality."

Institute programme director Dr Kyle Perrin said: "Although there isn't a huge amount of data ... we would say there's no benefit of treating a fever with paracetamol and there's potential harm in terms of making the illness worse or longer. So our recommendation would be not to treat a fever, but to use paracetamol as a pain reliever ... If you've got a headache or sore muscles it's reasonable to take it; it's very effective and safe in that setting."

But Dr Perrin did not call for health authorities to change their position.

"We don't think there's enough evidence yet to make a firm stand either way."

He also said that although parents were often concerned about their child having a convulsion from a high fever, they were probably not harmful.

"Most of the data in this area suggests that the risk of febrile convulsions isn't lowered by the use of paracetamol or other antipyretics. It seems that the febrile convulsion itself is to do with the infectious illness rather than the fever per se."

Dr Darren Hunt, the ministry's acting director of public health, said clinical practice was tending towards using medicines, if needed, to treat pain rather than fever. The ministry was likely to change its influenza advice to reflect this.

Fever in pregnancy, however, was a special case: paracetamol was recommended because it was important for the baby to reduce high temperatures.

Ministry of Health advice for influenza treatment at home:

"Take drugs that relieve pain and fever, eg, paracetamol or ibuprofen. Aspirin-type medications should not be used for children and young people."

Medical Research Institute:

"... there is an insufficient evidence base to support the use of antipyretics [fever reducers such as paracetamol, ibuprofen and aspirin] in the treatment of fever from influenza infection."