I am currently taking doxycycline and just started a 10 day course of terbinafine for resistant ringworm. i am on vacation next week at the lake and planned on swimming. both of these meds say avoid sunlight. does this mean i should not swim?

Both drugs can cause photosensitivity, i.e. increased sunburn with sun exposure. A strong sunblock (preferably SPF 30 or higher) usually prevents it. But still take it easy -- cover up as much as practical if sun exposure can't be entirely avoided.

Doxycycline and terbinafine can cause exaggerated sunburn. It is important to use proper sun protection such as sunglasses, clothing, and broad-spectrum sunscreen of at least SPF30 - reapply each time after swimming or every 2 hours (dry off first), whichever happens first. Contact your prescribing doctor and inform them if you experience significant sunburn.