A woman should consult her physician about any side effects that trouble her. In some cases, it is best to wait and see if the body adjusts to the current formulation; in others, it is worth trying a new formulation or a new method altogether.
Intermenstrual (“breakthrough”) bleeding is common during the first few cycles of hormonal contraception, as the body adjusts to the new hormonal milieu. This usually subsides after two or three cycles. If intermenstrual bleeding does not abate after three cycles, a woman should consult her physician, keeping in mind that switching to a new formulation can mean starting the adjustment process all over again.
In general, the lower the dose of estrogen, the higher the likelihood of intermenstrual “breakthrough” bleeding. The likelihood of intermenstrual bleeding and its potential halachic effects (see below) should therefore be taken into account by a physician when determining which version of hormonal contraception to prescribe.
Hormonal contraceptives are also sometimes associated with various other side effects, including changes in mood, and a decrease in sexual desire for some women.
Combined hormonal contraceptives can sometimes reduce breastmilk supply. Therefore, progesterone-only formulations are usually prescribed for nursing women. However, combined hormones are safe for use during breastfeeding, and can be used as necessary.
If breastfeeding has been well established, a woman beginning combined hormonal contraceptives may be able to preserve her milk supply by increasing both the length and frequency of feedings. If the baby is old enough (over six months), increasing solid foods can also help compensate for any decrease in breastmilk.