I am an active 33 year old male. I was prescribed seven days of 500mg levo for a persistent cough. I continued to commute to work by bicycle but otherwise did not strain myself. I drank lots of water as well. I experienced no side effects at all. Still had the cough though after seven days of the drug. The only problem I experienced was reading this message board after the first dose and feeling really scared. But nothing bad happened to me. Good luck!