Sulfa drugs are drugs which are derived from sulfanilamide. They were originally developed for use in treating bacterial infections and have since been applied to other medical uses as well. These drugs are not as widely prescribed as they once were because other drugs are more effective, some organisms have developed resistance to sulfa drugs, and a not insignificant number of the population is allergic to them. People with a sulfa allergy are not, however, allergic to sulfites and sulfates, along with other compounds which contain sulfur.
The first sulfa drug was discovered in 1932 and it laid the groundwork for a pharmaceutical revolution. Prior to the introduction of these drugs, people could die from bacterial infections which are today viewed as routine, because no drugs were available to treat them (penicillin was discovered earlier, but the medical applications of the drug were not realized until after sulfa had been introduced). The first sulfa drug spurred a number of competing companies to develop their own, leading to the widespread availability of such drugs just in time for the Second World War.
These drugs also triggered another revolution in the pharmaceutical industry: Tighter regulation of drug quality and purity. This unfortunately occurred in response to an incident in which numerous patients were poisoned by an impure batch of sulfa.
Sulfa drugs do not kill bacteria. Instead, they inhibit bacterial growth. When bacteria are exposed to the drugs, their uptake of folic acid is inhibited. This in turn prevents bacteria from reproducing. Today, antibiotics, drugs which actually kill bacteria, are generally preferred to sulfa drugs, although there are some conditions such as urinary tract infections for which these drugs will be prescribed.
Because of the allergy concerns, people with a history of reaction to sulfa drugs should make sure that it is noted in their charts. If a patient is prescribed a sulfa drug and begins to experience complications and side effects, these should be reported to a doctor. The doctor may recommend cessation of the drug and treatment with an alternative medication. People should also be aware that while many of these drugs contain “sulf-” in their names and are also labeled specifically with bold warnings due to allergy concerns, this is not the case with all such medications, and pharmacists should be alerted to drug allergies so that they can confirm the safety of any prescribed medications.