Tisha B'Av - Epilepsy Patient

Regarding the Tisha B’Av fast—does someone with controlled epilepsy need to fast on Tisha B’Av?Thank you. 

Eats and drinks as usual

I'm copying the halachos of Havdalah for one who needs to eat on the fast, as heard from the recorded halachah hotline of the Beit Hora'ah (extension 500):

This year, since the fast begins on Motzaei Shabbos, someone who is sick and needs to eat on the fast day must make Havdalah over a cup before eating. [Even someone who becomes sick on Tisha B’Av itself and needs to eat must make Havdalah before doing so.] If others who are fasting hear that Havdalah from him, they fulfill their obligation.

A woman who is permitted to eat on Tisha B’Av should make Havdalah herself and drink the cup [and there is no issue with this]. Some say her husband or someone else can recite Havdalah for her, and she drinks the cup—and the one saying Havdalah fulfills their obligation as well.

If she can’t drink the cup, she should recite Havdalah and give the grape juice to a child who has reached the age of chinuch (around 5–6 years old) to drink. If there’s no child, she may eat before Havdalah and hear Havdalah after the fast ends.

Havdalah text when made on the fast: Do not recite the verses said before the blessings (like “Hinei Keil...”). Begin directly with Borei Pri Hagafen, followed by Hamavdil bein Kodesh leChol. Do not say the blessing over spices. [If one has not yet said Borei Me’orei Ha’esh, they may say it during Havdalah. If they already did so on Motzaei Shabbos, they do not repeat it.]

Those making Havdalah on the fast should preferably use grape juice [this applies even to women].

The person making Havdalah should drink a revi’it of the cup (even though malei lugmav would technically suffice, since ideally one should drink a revi’it in order to be able to say a beracha acharonah, it is permitted for the sick person to drink that amount).

Someone drinking water on Tisha B’Av (with halachic permission) but not eating does not need to make Havdalah before drinking.