When your doctor mentions allergy testing, it’s easy to picture one generic test — a needle, some waiting, and a result. But allergy testing isn’t one-size-fits-all. There are several different types of allergy tests, each designed to identify different kinds of allergic reactions.
Understanding the options can help you feel more prepared, ask better questions at your appointment, and make sense of your results when they come back. Here’s a clear, jargon-free breakdown of the most common allergy tests used in South Africa.
1. Skin Prick Test
What it is
The skin prick test (also called a scratch test) is the most commonly used allergy test in South Africa. It’s quick, relatively painless, and can test for multiple allergens in a single session.
How it works
A small drop of allergen extract is placed on your forearm or upper back — there might be 10, 20, or more drops depending on what’s being tested. The skin beneath each drop is then lightly pricked with a tiny lancet. If you’re allergic to a particular substance, your skin will react with a small raised bump (called a wheal) within 15–20 minutes.
The size of the wheal helps your allergist determine the degree of sensitivity.
What it tests for
• Pollen (grass, tree, weed)
• Dust mites
• Pet dander (cats, dogs)
• Mould spores
• Common food allergens (peanuts, tree nuts, milk, eggs, wheat, soy, shellfish)
• Insect venom (bee, wasp)
Who it’s suitable for
Skin prick tests are suitable for most adults and children, including young babies in some cases. They are generally not recommended if you have severe eczema covering large areas of your arms, or if you cannot stop taking antihistamines before the test.
| ⚠️ Stop antihistamines 3–7 days before your skin prick test. They suppress your skin’s reaction and can lead to false negatives. Your allergist will confirm the exact timeline. |
2. Specific IgE Blood Test (formerly called RAST)
What it is
A specific IgE blood test measures the levels of allergen-specific antibodies in your blood. When your immune system overreacts to a substance, it produces a type of antibody called immunoglobulin E (IgE). High levels of IgE to a particular allergen confirm sensitisation.
How it works
A blood sample is taken — usually from a vein in your arm — and sent to a laboratory. Results typically take a few days to a week to come back. Unlike skin prick tests, this test is done in a lab rather than on your body, which means antihistamines don’t interfere with the results.
When doctors prefer a blood test over a skin prick test
• You have widespread eczema or psoriasis that makes skin testing difficult
• You can’t safely stop taking antihistamines or certain medications
• You’ve had a severe anaphylactic reaction and skin testing poses a risk
• Results from a skin prick test were unclear and need confirmation
• You’re a very young child where skin testing is impractical
What it tests for
Blood tests can test for most of the same allergens as skin prick tests, and are particularly useful for food, pollen, dust mite, and venom allergies.
3. Patch Test
What it is
A patch test is different from the other two — it’s used to identify contact allergies, also called allergic contact dermatitis. This is the type of reaction you get when your skin touches something it’s sensitive to: a metal, a fragrance, a preservative, or a cosmetic ingredient.
How it works
Small patches containing different allergens are applied to your upper back and left in place for 48 hours. You’ll return to the clinic after 48 hours for the patches to be removed, and again at 72–96 hours for a final reading. Any redness, swelling, or blistering under a patch indicates a positive reaction.
Common allergens tested in patch tests
• Nickel (found in jewellery, belt buckles, and zippers)
• Fragrances and perfumes
• Preservatives in cosmetics and skincare
• Rubber and latex
• Hair dye ingredients (such as PPD)
• Adhesives
Who it’s for
Patch testing is typically done by a dermatologist and is recommended when someone develops a recurring skin rash in areas that come into contact with specific objects — jewellery on the wrist or neck, for example, or a rash that appears wherever skincare products are applied.
4. Oral Food Challenge
What it is
An oral food challenge (OFC) is considered the gold standard for diagnosing food allergies. It involves consuming increasing amounts of a suspected food allergen under close medical supervision to confirm whether a true allergy exists.
How it works
The challenge is carried out in a clinical setting — usually a hospital or specialist clinic — where a medical team is on hand to monitor you and manage any reaction. You’ll be given very small amounts of the food to start, with doses gradually increasing over several hours. If no reaction occurs, the food allergy is ruled out.
When it’s used
• To confirm a suspected food allergy when skin and blood tests are inconclusive
• To check whether a child has outgrown a food allergy
• To reintroduce foods that were previously avoided
| ⚠️ An oral food challenge should never be attempted at home. It must be done under medical supervision with emergency medication readily available. |
Which Test is Right for You?
Your allergist will recommend the most appropriate test based on your symptoms, medical history, and the allergens being investigated. In many cases, more than one type of test will be used to build a complete picture.
| Test | Best For | Results | Antihistamines OK? |
|---|---|---|---|
| Skin Prick Test | Airborne & food allergens | 15–20 minutes | No — stop 3–7 days before |
| Blood Test (IgE) | Most allergens, esp. when skin testing not possible | 3–7 days (lab) | Yes |
| Patch Test | Contact/skin allergens | 48–96 hours | Yes |
| Oral Food Challenge | Food allergy confirmation | Same day | Discuss with doctor |
| Frequently Asked Questions |
| Can I have more than one type of allergy test at the same appointment? |
| Yes — your allergist may run a skin prick test and order a blood test at the same visit, especially if they want to cross-reference results or test for a wide range of allergens. |
| Are allergy tests accurate? |
| Allergy tests are reliable when interpreted by a qualified allergist alongside your clinical history. A positive result on a test doesn’t always mean you’ll have a reaction — and a negative result doesn’t always mean you’re in the clear. Context matters, which is why professional interpretation is essential. |
| Can I get allergy tested at a pharmacy or GP? |
| Some GPs can perform basic skin prick tests or order IgE blood tests. For comprehensive testing or complex cases, a referral to an allergist or clinical immunologist is recommended. |
| Is allergy testing covered by medical aid in South Africa? |
| Most major medical aids cover allergy testing when it’s referred by a doctor. Check your scheme’s benefits and ask your allergist’s practice manager before your appointment to avoid unexpected costs. |
The Bottom Line
There is no single “best” allergy test — the right one depends on your symptoms, your age, and what your doctor suspects. The most important step is to see a qualified allergist rather than trying to self-diagnose through elimination alone.
Once you know what you’re dealing with, managing your allergies becomes so much more straightforward.
