Unusually for drugs developed to tackle chronic illness, both orlistat and sibutramine have strict limitations imposed by their SPA licenses on their length of use:

  • Orlistat is licensed for use up to 24 months. NICE recommends that it is used for up to a maximum of 12 months normally and up to 24 months in exceptional circumstances.

  • Sibutramine is licensed for 12 months of treatment.

Available data suggest that many patients receive only 2 or 3 months of treatment. The probable explanation for this is likely to be unmet and unrealistic expectations – on the part of the patient or clinician. The rate of weight loss in the first few weeks is often too slow to satisfy a patient who has been struggling to lose weight for months, and possibly years. Other reasons might include poor pretreatment counselling – in the case of orlistat leading to perceived unacceptable GI side-effects, in the case of sibutramine to unpleasant but often transient dry mouth, headache or constipation.

The important thing is to use the drugs for as long as it takes, within the licensing regulations, to achieve the purpose for which they were started. After the initial weight-loss phase, drugs can play a crucial role in preventing weight regain, both prolonging the beneficial effects of weight loss and allowing more time for the patient to reinforce newly learned dietary and exercise habits.