The government's chief medical officer, Sir Liam Donaldson, has urged parents of children showing the symptoms of swine flu should still give children Tamiflu, despite more than half of children who take the drug exhibiting side effects such as nausea and nightmares.

Tamiflu, the drug being used to fight swine flu virus, can also produce stomach pain, diarrhoea and sleeping problems in children as well as adults.

Research into using the Tamiflu drug also showed that children taking the drug to fight swine flu find it difficult to concentrate, which may effect their school performance in general and school exam results.

The Department of Health issued a statement to say that there was no causal association between Tamiflu (or Relenza) and an increase in neuropsychiatric events. Roche, the Swiss company which makes Tamiflu, issued a similar statement.

Over 150,000 Tamiflu packs were distributed by the new National Pandemic Flu Service during a weekend in July 2009 alone -  despite the warnings from some experts that this could increase the resistance of the swine flu virus.

The phone and internet service lets people obtain Tamiflu without a positive diagnosis of swine flu from a doctor. 

Sir Liam Donaldson, the chief medical officer, also announced another 110,000 new cases of swine flu for the 3rd week in July 2009 -  up only slightly from 100,000 the week before.