Medicines can poison people if used improperly. Many children are poisoned each year by overdoses of aspirin. If aspirin can poison, just think of how many other poisons might be in the medicine cabinet.
Aspirins and most prescription drugs come with child-resistant caps. Check to see if they do, and that they are properly secured. Check prescriptions before leaving the pharmacy to make sure the medicines are in child-resistant packaging. These caps have been shown to save the lives of children.
Throw out all out-of-date prescriptions. As medicines get older, the chemicals inside them can change, so what was once a good medicine could become a dangerous poison. Flush all old drugs down the toilet, rinse the container well and discard it.
Are all medicines in their original containers with the original labels? Prescription medicines may or may not list ingredients. The prescription number on the label will, however, allow rapid identification by the pharmacist of the ingredients should they not be listed. Without the original label and container, a person can't be sure of what they are taking.
Additionally vitamins or vitamin/mineral supplements contain iron are should also have child-resistant packaging. Most people think of vitamins and minerals as foods and, therefore, nontoxic, but a few iron pills can kill a child.