In our latest question and answer, the pharmacist discusses whether or not melatonin supplements are safe to take if you are on birth control pills.
Is it okay to use melatonin sleep aids at night while on lutera 28 for birth control? Will it lower the effectiveness of the birth control?
There is a potentially minor interaction between birth control pills and melatonin. There is a chance that taking them together can increase melatonin concentrations in the body due to the estrogen in birth control pills inhibiting its metabolism.
This interaction doesn't appear to be overly significant however and, in general, it is considered safe to take melatonin if you are on birth control pills
There are no studies that have reported melatonin can reduce the effectiveness of birth control pills.
Most birth control pills contain both an estrogen and a progestin. These are known as "combined hormone birth control pills." While our natural produced estrogen and melatonin levels in the body may influence one other, there are no studies that show that melatonin will decrease the efficacy of birth control pills.
On the other hand, melatonin levels can be increased if taken with estrogen-containing birth control pills. This is because estrogen is a weak inhibitor of the metabolizing enzyme CYP1A2 and melatonin is metabolized, at least partially, by CYP1A2.
Due to the inhibition of these metabolizing enzymes, melatonin may take longer to be metabolized and therefore have a more prolonged effect than usual. The result of this could potentially be increased side effects of melatonin, such as:
Nevertheless, as stated earlier in this answer, it doesn't appear to be that significant.
Birth control pills that only contain a progestin (these are known as 'minipills') are not thought to interact with melatonin at all.
It is important to point out that melatonin is thought to have complex effects on endogenous (i.e. naturally produced) estrogen. It has been researched for its role in inhibiting estrogen-stimulated breast cancer growth by "down-regulating" estrogen receptors and possibly reducing endogenous estrogen production.
Even though melatonin and estrogen have complex interactions in the body, there is no evidence that melatonin supplementation has any effect on the estrogen contained in birth control pills.