Would modafinil have adverse effects on someone who already has tourette's in treating their adhd?

Proceed with caution: Among patient's with Tourette's, it is not uncommon to find ADHD as well. And there are studies with drugs used to manage ADHD. So while the general rule is that stimulants make tics worse, studies with both methylphenidate and Stattera suggesting that these drugs do not worsen TS at normal doses. However, I could find nothing on modafinil. The other two drugs might be better first choices.

It may: Modafinil may increase tics and other symptoms of Tourette’s. Its use should be closely monitored by your doctor. Other side effects of modafinil, for your information, may include headache, insomnia, dizziness, and loss of appetite.