The UK and the US differ markedly in what the drug regulatory agencies require drugs manufacturers to admit in their labelling. To take one example, here's what the manufacturers of Effexor (venlafaxine) say in their US label compared with their UK label (spelled Efexor).

* Long-term use
US Label, 1996: 'The effectiveness of Effexor in long-term use, that is, for more than 4-6 weeks, has not been systematically evaluated in controlled trials' (Comp Data Sheets, 1996).
UK Data Sheet, 1996: 'Efexor has been shown to be efficacious during long-term (up to 12 months) treatment' (Comp Pat Info Leaf, 1996).

* Risk of dependence
US Label, 1996: 'While Effexor has not been systematically studied in clinical trials for its potential for abuse, there was no indication of drug-seeking behaviour in clinical trials.'
UK Data Sheet, 1996: 'Clinical studies have shown no evidence of drug-seeking behaviour, development of tolerance, or dose escalation over time among patients taking Efexor.'

* Problems on withdrawal
US Label, 1996: 'While the discontinuation effects of Efexor have not been systematically evaluated in controlled clinical trials, a retrospective survey of new events occurring during tapering or following discontinuation revealed the following six events which occurred at an incidence of at least 5 per cent and for which the incidence for Effexor was at least twice the placebo incidence: asthenia, dizziness, headache, insomnia, nausea and nervousness . . .'
UK Data Sheet, 1996: 'Discontinuing Efexor: No definitive withdrawal syndrome has been observed with Efexor. During clinical trials, symptoms reported on abrupt discontinuation included fatigue, nausea dizziness, and one episode of hypomania . . .'

* Gradual withdrawal
US Data Sheet, 1996: 'Patients who have received Effexor for six weeks or more should have their dose tapered gradually over a two-week period.'
UK Data Sheet, 1996: 'Patients who have received Efexor for six weeks or more should have their dose reduced gradually over at least a one-week period.'