manifest. 1  readily perceived by the eye or the understanding; evident; obvious; apparent; plain: a manifest error. 2  Psychoanalysis. of or relating to conscious feelings, ideas, and impulses that contain repressed psychic material: the manifest content of a dream as opposed to the latent content that it conceals.
In medicine, an adverse effect is an undesired harmful effect resulting from a medication or other intervention such as surgery. An adverse effect may be termed a  side effect , when judged to be secondary to a main or therapeutic effect.
The truth is that nearly all medications, both over-the-counter and prescription, have some kind of undesirable and sometimes dangerous aftereffects, from muscle aches to death. Even with the federal regulations that oversee these drugs, side effects are inevitable. For federal regulators, though, the benefits sometimes outweigh the dangers. Each year, about 4.5 million Americans visit their doctorâs office or the emergency room because of adverse prescription drug side effects.