Not all prescription drugs are 100 per cent safe. You can see that the doctors prescribes a medicine and then writes down one or two more to counter the side effects of the medicine. For example, if the doctor prescribes some emotion control pill, he or she will definitely prescribe some sort of multivitamin supplement to make up for the loss of these vitamins in your body.
This happens more in the case of Allopathic medicines. The most common allergies associated with the prescription drugs are weakness, restlessness, and lack of sleep. As the chemicals bring in a change in your body, the body uses all of the available resources of the extra energy required to sustain. This in turn creates weakness, for which, the doctor will again prescribe some multivitamins and glucomin drugs.
Restlessness is caused due to that fact that you are weak after taking the drug and the new chemical interactions with the drug are going on within your body. Same is the reason for lack of proper sleep. Among other allergies to some prescription drugs are vomiting, fever, and respiratory problems. But as the doctors know it before hand; they prescribe drugs that take care of these side effects. If you still face problems after taking the drugs, stop the medication immediately and contact the doctor.