Listed below are some of the known interactions between Modafinil and other chemicals, plants or pharmaceutical medications. This is not a comprehensive list. Substances which are not listed below may still have significant and/or dangerous interactions with Modafinil.

CHEMICAL	Relationship	KNOWN ISSUES	POSSIBLE SYMPTOMS	REFS
Birth Control Hormones / Pills	Direct	The prescribing information for Modafinil products clearly states there is an interaction with hormonal contraceptives, but provides no information about how this is known. The mechanism is that Modafinil upregulates (increases effectiveness of) the enzyme CYP3A4/5, which is involved in the metabolism of the contraceptive hormones and thus breaks them down more quickly. We have only been able to find a single paper that looked at the issue in humans and it showed that daily 400mg doses of Modafinil for a month significantly reduced the levels of the hormone estradiol and norgestimate in the 16 women studied. There is no direct research showing actual increases in impregnation rates and it is unclear whether less frequent or lower doses of Modafinil would have clinically significant effects on hormonal birth control. Some physicians have recommended increased doses of birth control as a solution.	reduces contraceptive effectiveness	Robertson 2002 Robertson 2000
Opiates/Methadone	Indirect Anecdotal	Methadone is metabolized by several liver enzymes in the CYP2* cluster, with CYP3A4 being an important metabolizer. Because modafinil up-regulates CYP1A2, CYP2B6, and CYP3A4/5, the action of methadone may be substantially shortened. Erowid also received one experience report from a reported methadone user who found that they had to redose with methadone every few hours to avoid opiate-withdrawal after taking large doses (> 1000mg) of modafinil.	decreases duration of methadone effects	Wang 2003 Erowid Exp 34028
If you have a negative drug interaction to report, please let us know.