THE Health Department has ordered suppliers of two controversial diet pills to withdraw all their products amid fears they could cause heart problems. The Pharmacy and Poisons Board has given the manufacturers and suppliers of the 31 brands containing fenfluramine and dexfenfluramine four weeks to appeal against proposals to de-register the products. One supplier has already moved to pull its pills off the market and a local manufacturer has advised the Government it will do the same. The moves followed suggestions of a link between the pills and heart valve disease. 'We advise people not to use these two drugs until more information is available,' a Health Department spokesman said. 'Those already using any of these drugs should consult their doctors on gradual withdrawal to avoid withdrawal effects.' The pills suppress the appetite and are supposed to be prescribed only to the clinically obese. Side effects include diarrhoea and drowsiness. Concern was raised after the United States Food and Drug Administration found 30 per cent of users had abnormal echocardiograms - a measurement of the function of heart valves.