Dr Thomas Stuttaford's next online forum (live on February 13, after 1pm) is: Contraception. To ask the doctor your question on this topic and to read other recent topics he has answered click here

A 28-year-old unmarried reader has asked whether she should heed the advice of the public health minister and change from the combined pill as a contraceptive to an injection every three months from her GP.

The minister’s advice to GPs to consider every type of contraceptive available would be accepted by most doctors. However each method must be chosen to provide the best option for the patient rather than as a cost-saving exercise.

The pill has fewer side-effects than other forms of contraception, but it may also react with other drugs that can affect its action. The side-effects of the combined pill are usually acceptable provided that it is not taken by women older than the mid-thirties.

Unfortunately 88 per cent of women forget to take the pill regularly, according to research. In other cases its absorption may be compromised by vomiting or diarrhoea. This latter problem is especially important in older women taking the progestogen-only mini pill.

The advantage of the three-monthly injection Depo-Provira medroxyprogestrone is that the patient can be certain that she has taken it and, provided she keeps her appointments, will be covered regardless of a lapse of memory, illness or an impulsive desire to become pregnant.

The disadvantages of Depo-Provira are not always acceptable to patients. Some suffer from one or more of a variety side-effects that include weight gain, acne, facial hair, mood changes including depression and irritable aggression, headaches, visual disturbances and migraine.

From my own experience, patients taking Depo-Provira are most likely to be upset by irregular vaginal bleeding. This is especially likely to cause problems in the first few months.

I always found that Mirena, a T-shaped intrauterine system that lasts five years, is very acceptable to women but it is usually only recommended for older patients in long-term relationships. The use of an implant is usually considered to involve too much fuss.

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