There’s nothing like a new drug to cause amnesia in the medical community. Fresh from the Women’s Health Initiative and other massive studies showing that hormone replacement therapy causes cancer, doctors are now waxing lyrical over the benefits of a new hormone for contraception.

The new Pill on the block is Yasmin, from Schering Health Care and now available in the UK. With this combination contraceptive, ethinyloestradiol is used for the oestrogen portion, but it’s combined with the new progestogen drospirenone. This progestogen differs from other synthetics, such as levonorgestrel, in that it acts like spironolactone (Aldactone), a ‘water pill’, or diuretic, used to treat high blood pressure by causing the kidneys to eliminate excess water.

Yasmin works by the belt-and-braces principle, typical for the Pill. It tricks the body into thinking it has ovulated while, at the same time, making it difficult for sperm to enter the womb or into any eggs that may have managed to circumvent all the barriers and implanted themselves in the womb lining.

However, Yasmin is largely being sold as the ‘lifestyle’ Pill: unlike your usual contraceptive, drospirenone not only does not cause weight gain, but can also help you slim. It’s being sold as “the pill for well-being” with a “demonstrable positive effect” on the skin and premenstrual symptoms. On this basis, Yasmin was welcomed with open arms by women who gained weight on the old Pills, and by doctors who felt that, if a contraceptive can help clear spots and lose weight, a woman would be more likely to take it (Eur J Contracept Reprod Health Care, 2000; 5 [Suppl 3]: 9-16).

These claims are based on research showing that Yasmin can enhance quality of life by a more than 7 per cent improvement in weight, skin, hair, libido, mental wellbeing and some rather undefined thing called ‘attractivity’ (Schweiz Rundsch Med Prax, 2003; 92: 1177-84). As well as being a weight-loss agent, Yasmin is also being hailed as a cure for acne, fluid-related symptoms and menstrual problems (J Reprod Med, 2003; 48: 79-85).

With this Pill, you also supposedly don’t need as much progestogen per day as drospirenone is especially potent (Eur J Contracept Reprod Health Care, 2002; 7 [Suppl 3]: 13-8).

Although Yasmin has been sold as the ‘slimming’ pill that also happens to prevent pregnancy, the facts don’t bear this out. In a study of women with polycystic ovarian disease, the percentage of body fat in the women taking Yasmin increased, albeit with no overall change in body mass index (J Fam Plan Reprod Health Care, 2004; 30: 163-5). So, although Yasmin doesn’t come with the water retention of other Pills, it doesn’t work any better in preventing the deposition of extra body fat.

Yasmin also doesn’t seem to work any better than the ordinary Pill in clearing acne (Cutis, 2002; 69 [4 Suppl]: 2-15).

Most ‘water pills’ cause a loss of potassium, but spironolactone has a potassium-sparing effect, so Yasmin may result in an excess of potassium in some women.

Spironolactone has also caused tumours in animals, a side-effect which may or may not apply to humans. And that’s not including all the other side-effects of the Pill, which do apply