get your hidden health stat up. Eat healthy foods and vitamins roughly twice a day or a little less often (~every 18 hours) It should help keep you from getting, and help get rid of health issues.
The way it works:
The hidden health stat the current healthiness try to balance out by randomly one moving closer to the other, but the hidden health stat that doesn’t actively effect anything defaults to 0. When doing unhealthy (-) or healthy (+) things they effect your hidden stat which in turn effects your current healthiness.
Other things that can negatively effect your health if you don’t counter them with vitamins/healthy food are:
Mutagens, radiation, addictions, junk food, and drugs (the illegal variants)
Healthy things:
Healthy food, meat, veggies etc… vitamins, influinza shots, and other shots of a non-illicit substance types
Basically if its normally healthy/unhealthy to do in real life its healthy/unhealthy in CDDA too.