I've only taken Phenytoin (Dilantin) for seizure control.
Be thankful you live where you do.
It got up to about 116 degrees here.
I only go out early or late in the day.
I don't even have to go outside to have side effects from the heat.
I set my thermostat inside at 80... which is comfortable to me.
I still have no ambition to do anything but eat, sleep, and watch TV.
I get dizzy more than during cooler weather.
Humidity over 20% makes it much worse here.
If you go outside.....
Drink a lot of water, wear a hat and sunglasses!