I've been taking nv diet pills. Ie been experience headaches but only at night? Can I take tylenol (acetaminophen)?

Stop the diet pills! Diet pills are a bad idea (almost as bad as the tape worm ad in the picture). Losing weight is best done safely, through diet and exercise. Indeed, you headaches are likely related to your diet pills. Rather than taking tylenol, (acetaminophen) stop taking the diet pills and see if that makes your headaches go away.