There are several side effects associated with consumption of the maca root, none of them particularly serious. There are many physical conditions and medications for which there simply isn’t enough information to draw a conclusion. There has been very little in the way of studies regarding the possible adverse effects of maca, so reports of side effects are essentially anecdotal evidence – although well worth taking into consideration.
Maca may have the effect of making both men and women more fertile. It’s possible that it can disrupt birth control, since contraceptive pills operate by manipulating estrogen. Maca can speed up the menstrual cycle in young women who have been taking maca – or eating products with maca as an ingredient – for a long time. It has also been suggested that women who are pregnant or nursing should probably not use maca until the baby has been born and weaned.
People who take maca late in the day may become jittery from the increased energy maca can impart. Because it probably does much of its work through the endocrine system, people with a thyroid condition or who are on thyroid medication can become jittery from using maca powder. It has been tested at high doses and shown to have no toxic effects.