There are a few different types:
Skin test: A doctor injects a tiny amount of the drug under your skin and watches to see if you have a reaction. Skin tests only work for some types of drugs, like penicillin and other antibiotics, muscle relaxants, and some cancer drugs.
Patch test: A doctor puts a small amount of a drug on your skin. After 2 to 4 days, the doctor will check for a reaction. This test can check for delayed allergic reactions to antibiotics, anticonvulsants, and other drugs.
Blood test: Lab tests may help diagnose some allergies to antibiotics and other drugs.
Talk with your doctor to see which is best for you.