Sulfa Drugs Allergy

Sulfa drugs allergy is a condition which describes the adverse drug reactions to sulfonamides. Sulfonamides are medicines that prevent the growth of bacteria in the body and sulfa drugs are used to treat bacterial infections of different kinds. Sulfonamide group of drugs may be with or without antibiotic characteristics. Common sulfonamide antibiotics are sulfamethoxazole, trimethoprim-sulfamethoxazole and erythromycin-sulfisoxazole. Besides these, there are many other medications like furosemide (Lasix), hydrochlorothiazide (Microzide), glyburide (Glynase, Diabeta, Micronase), glimepiride (Amaryl), celecoxib (Celebrex), and sumatriptan (Imitrex), which contain sulfonamide.

Approximately 3% of the general population show sulfa drugs allergy, when treated with sulfonamide and other similar antibiotics. People with immune-system related diseases like AIDS, appear to be at higher risk for sulfa allergy, showing a much higher prevalence, at about 60%. Patients showing hypersensitivity reaction to one member of the sulfonamide class are likely to have a similar reaction to others. Sulfa allergy may also lead to Stevens Johnson Syndrome (SJS) which is a highly acute immune-complex-hypersensitivity condition, that affects the skin and mucous membranes.

Antibacterial sulfonamides are synthetic antimicrobial agents that contain the sulfonamide group. They are structurally different from the non-antibiotic sulfonamides and appear to be much more likely to result in allergic reactions. The allergies caused by sulfa drugs are common, and hence these medications should be prescribed carefully. Sulfates and sulfites are chemically unrelated to the sulfonamide group and do not cause the same hypersensitivity reactions which are seen in the case of the sulfonamides medications.

Symptoms
The following symptoms are generally seen in persons suffering from sulfa drugs allergy.

• Skin and Lung Reactions: Skin reactions are one of the most common reactions of sulfa drugs. The adverse effects related to skin may range from skin rashes to life-threatening Stevens Johnson Syndrome (SJS) and toxic epidermal necrolysis. In some cases, an increased sensitivity to sunlight (photosensitivity) is also possible. Sulfa medication and allergy can also affect the lungs with pneumonia-like reactions, and worsen asthma problems.
• Blood reactions: Sulfa allergy can affect blood cells, causing a decrease in the number of white blood cells, red blood cells, and platelets.
• Aching Joints and Muscles: Sulfa drugs allergy may result in sensations of severe joints and muscle pain. Both the symptoms occur within a week or two after the medication starts.
• Breathing problems: An allergy to sulfa drugs can also worsen asthma, due to its effect on the lungs.

Treatment
The diagnosis of sulfa drugs allergy is made when a person on sulfa medication experiences the allergy symptoms. There are no specific skin or blood tests available to diagnose sulfa allergy. In most cases, if a person is diagnosed with the allergy, the sulfa medication is immediately stopped. However, merely avoiding medicines with "sul" or "sulfa" prefix , is not the rule of thumb in cases of this type of allergy, as there are many generic names or brand names of medications that contain sulfonamides which may not start with these prefixes.

In some cases, a person needing sulfa drugs can be desensitized to the medication by initially giving very small amounts of the medication, which is gradually increased in amount, over a period of time. This process helps the body to tolerate the medication. If the allergy symptoms are very severe, the patient should be treated by an allergist, who is experienced in the management of drug allergies.