I agree with Sarahsweets about considering if it is worth asking the friend if she would be willing to keep what you shared private.

I also think it may make sense to have a strategy for how you plan to respond if someone asks you about the meds. You don't need a detailed plan, but a general idea of what you'd like to say may be helpful in the case they catch you off guard.

I am hopeful that your friend honors you properly and if not that this information surfacing somehow turns out to be a positive experience. While I agree discrimination is very real, it doesn't always have to be the outcome.