No, you probably cannot take legal action against him. People are not liable for giving bad advice that is followed, unless there is some special relationship or duty. For example, doctors are liable for medical malpractice *because* they are doctors--they have a duty imposed by their licensing and the doctor-patient relationship. But your boss is not a medical professional: he can give any medical advice he likes without liability, because it is your responsiblity if you choose to follow it. Also, companies don't generally have to provide sick days or time off for doctor visits and can terminate employees for absenteesm, so he could refuse to give you time for the doctor.