Some medicine can lose their effects to a greater or lesser extent, such as oral suspensions , that are more likely to lose their active ingredient faster than oral solids, data also mentioned in my research.

It is important to differentiate between it is not good to take them again because they are bad, and not take them because they will not have the desired effect to counteract a symptom.

Anyways, also said in my article, there have been found some medicines with the 90% of effectiveness, after having expired 30 years ago.