Anyone that has endured physical training and has a tendency to over-exert himself has likely heard of muscle relaxants. These are medications that are designed to reduce muscle tone and relieve stress on the skeletal and muscular systems due to physical activity. Pain and muscle spasms that occur in conjunction with excessive physical activity have also been treated with the use of muscle relaxants, with varying results. These medications are generally not given out over-the-counter, primarily due to the numerous side effects and problems that can occur with use. There are several things that a doctor would have to consider prior to prescribing anyone any form of relaxant (whether they are spasmolytics or neuromuscular blockers), primarily to reduce the chances of the patient developing unpleasant side effects due to use.
As with a variety of medication, doctors are required to check for allergies to muscle relaxants. Different drugs have different basic chemical compositions, so if a patient is allergic to one particular drug, others may be suggested. While the drug may be more effective than the alternative, it does allow both patient and doctor to avoid any unpleasant reactions. In most cases, an allergy to a specific component on any drug, not just muscle relaxants, can cause potentially fatal reactions as side effects. Whether or not a person has any allergies to certain medications can also help the doctor narrow down the options for what drugs can be given. Other allergies must also be checked, such as certain types of certain types of foods, various preservatives, and edible dyes.
Pregnant women are generally advised by doctors to avoid taking any form of relaxant. There is little indication on how the medication behaves during pregnancy, such as whether or not the placenta and the mother's body are able to effectively separate the drug from the nutrients the fetus needs. It is also unknown what effects the drugs might have on a developing fetus, if there are any. Just to be on the safe side, most doctors would advise against taking such things during pregnancy and would probably recommend alternative medications if their patient becomes pregnant while taking the relaxants. Studies have shown that these drugs can cause birth defects in animals, with sufficient data to suggest that it can also occur to humans as well.
Some of these medications have not been fully tested on both the elderly and children. Both age groups have immune systems and metabolisms that function on different levels from the average adult's, which makes it difficult to effectively estimate whether or not the effects would be the same as if an adult used the medication. Theoretically, adjusting the dose given to these age groups should be enough to compensate, but most medications are packaged for adults, which makes it difficult to accurately reduce the dosage. Additional problems may also appear in children while using certain relaxants, because their bodies are generally more prone to developing side effects than any other age group's.
Other medications and medical problems must also be considered before any sort of muscle medication is prescribed. Drug interaction is a serious concern, as is the possible interaction of side effects with alcohol or other substances. As such, most doctors would ask questions relevant to this before making a prescription. This is done to avoid complications and side effects that might arise from mixing two incompatible substances together in the body.