Why can taking medicine to relieve symptoms of an illness be bad?

Isn't always. If you have an acute upper respiratory tract infection with mostly nasal conjestion i would offer a drying agent-you can't sleep otherwise.The cough that accompanies bronchitis is often debilitating and should be treated to prevent spread of "bugs".If you have to get up 4 times a night to urinate a prostatic urethreal dilator(relax the prostate)is not bad.Using Estrogens in menopause is often good.