Penicillin G Allergy Test
This page explains the penicillin g allergy test, what it measures, and how to arrange it. A penicillin G allergy test checks your blood for immune proteins that may react to penicillin G, a common antibiotic. It is usually ordered when a person reports a past reaction to penicillin and a clinician wants more information before deciding whether penicillin can be used safely.
- Sample type
- blood
- Category
- Allergy
- Turnaround
- 1-3 business days
- Price
- $49
- Referral
- Not required
A penicillin G allergy test checks your blood for immune proteins that may react to penicillin G, a common antibiotic. It is usually ordered when a person reports a past reaction to penicillin and a clinician wants more information before deciding whether penicillin can be used safely.
What it measures
- Penicillin G-specific IgE — An immune protein that can trigger immediate allergic reactions; its presence may suggest sensitivity to penicillin G.
- Total IgE — A general measure of allergic antibody levels, used for context rather than as a stand-alone allergy test.
- Specific IgE to related penicillins — Checks for reactions to closely related antibiotics, such as amoxicillin or ampicillin.
- Other beta-lactam markers — May include related antibiotic components to help clarify cross-reactivity.
Who it is for
This test is typically ordered by an allergist, immunologist, or primary care clinician when a patient has a history of a possible penicillin reaction and needs clearer information before treatment.
Preparation
No fasting or special preparation is usually required. Tell your clinician about all medicines you take, especially antihistamines, which may affect some allergy tests.
Results and what they mean
Results are reported as negative, positive, or a measured level for each marker, depending on the lab. A clinician interprets these results alongside your symptoms and medical history; a positive result does not always mean you are truly allergic, and a negative result does not rule out every type of reaction. This is general information, not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the penicillin g allergy test is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Does this test hurt?
It uses a standard blood draw, so you may feel a brief pinch when the needle goes in.
Do I need to stop my allergy medicines?
Ask your clinician. Some antihistamines can affect allergy testing, but do not stop any medicine without checking first.
Can this test prove I am allergic to penicillin?
No single test is perfect. Your clinician combines the result with your history and may recommend other testing.
How soon will I get results?
Most labs return results in about 1 to 3 business days, though timing can vary.