Allergy - Sulpha Antibiotic Test

Sulfa drugs can treat a range of health problems from eye infections to rheumatoid arthritis (RA). But if you get a rash or more serious reaction when you take one of these drugs, you may have a sulfa allergy. Sulfa drugs, also called sulfonamides, include antibiotics and other types of drugs. Allergies happen most often with antibiotics. Around 3% of people have some type of reaction to them. If you are allergic to one sulfonamide antibiotic, there is a risk that you might also react to other sulfonamide antibiotics. A simple blood plasma test is used to check sulfamethoxazole and sulfisoxazole levels in blood serum.

It is recommended that you should either wear a sleeveless or a short-sleeved shirt to make it easier for you and the technician who will be drawing the blood. Wearing a shirt with full- sleeves that can easily be rolled-up is also fine. No special preparation is needed before having this test. Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.

Reference ranges:
Therapeutic: 5.0-15.0 mg/dL
Toxic: >20.0 mg/dL
If you’re allergic to sulfa drugs, or any other medication, you may have one or more of these symptoms: headache, trouble sleeping, cloudy urine (crystalluria), and low blood count, skin rash or hives, itching, breathing problems, swelling and serious skin reactions such as:
Sulfonamide drug hypersensitivity syndrome: Rash, fever, and organ problems begin within 1 to 2 weeks after you start the drug.
Drug eruption: Red or swollen, rounded patches form in 30 minutes to 8 hours.
Stevens Johnson syndrome: This potentially life-threatening reaction causes skin to blister and peel off.

A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
A 70% alcohol pad is used to clean the skin
A needle is then kept in line with and injected into a vein that can be seen from the skin
The blood is dragged out from the needle by a nozzle, saved in a vessel and sealed with your name
The sample is then taken to a lab for examination