Quick Facts
- Sample: Blood (serum)
- Fasting: Not required
- Turn-around: 3–5 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Avoid dangerous reactions – confirm your Cefaclor allergy status before exposure or treatment
- No anaphylaxis risk – safe blood test alternative to skin testing
- High accuracy – ImmunoCAP testing shows ~89% sensitivity and near-100% specificity (Thermo Fisher 2022)
- Test anytime – no interference from medications or skin conditions
- Reduce healthcare costs – early detection cuts ER visits by up to 30% (Johns Hopkins 2023)
Who Is This Test For?
- Individuals with previous allergic reactions to Cefaclor or similar antibiotics
- People with a history of penicillin or cephalosporin allergies
- Patients needing pre-treatment allergy risk assessment before Cefaclor prescription
- Anyone experiencing hives, rashes, swelling, or breathing difficulty after antibiotic use
- Those seeking to confirm or rule out drug allergy for safer treatment planning
How It Works – Just 3 Steps
- Order online – No doctor's note required; select your test and preferred lab location
- Visit the lab – Quick blood draw at a lab location near you
- Get results – Receive confidential results within 3–5 days in your online account
FAQ
What does this test measure? It detects IgE antibodies specific to Cefaclor, indicating allergic sensitization to this antibiotic.
Can I take this test while on medications? Yes—blood allergy testing works regardless of current medications or antihistamine use.
What if I've never taken Cefaclor before? The test can assess pre-exposure risk, especially if you have other antibiotic allergies.
How accurate is this test? ImmunoCAP methodology provides approximately 89% sensitivity and nearly 100% specificity (Thermo Fisher 2022).
What should I do if my results are positive? Discuss findings with your physician to plan alternative antibiotics and avoid future Cefaclor exposure.
More Details
What is the purpose of this test?
The Cefaclor Allergy IgE Blood Test measures specific IgE antibodies in your blood that signal an immune-mediated allergic reaction to Cefaclor. Cefaclor is a commonly prescribed antibiotic used to treat bacterial infections of the ears, skin, lungs, throat, and respiratory tract. When your immune system mistakenly identifies Cefaclor as harmful, it produces IgE antibodies that trigger allergic symptoms ranging from mild skin rashes to severe, life-threatening anaphylaxis. This test helps confirm or rule out allergic sensitization, enabling safer antibiotic selection and preventing potentially dangerous reactions (NCBI 2014).
Who would benefit from this test?
This test is especially valuable for individuals with a history of antibiotic allergies, particularly to penicillin or other cephalosporins, as cross-reactivity occurs in some patients. You should consider testing if you've experienced allergic symptoms after taking Cefaclor, such as hives, itching, rashes, swelling of the tongue or throat, or difficulty breathing. It's also useful for pre-treatment screening if your doctor plans to prescribe Cefaclor and you have concerns about potential allergy. Drug allergies account for over 10% of adverse drug reactions, making proper identification critical for patient safety and reducing healthcare costs (CDC 2023).
When should I order this test?
Order this test if you've experienced any allergic symptoms during or after Cefaclor use, including skin reactions, respiratory distress, or gastrointestinal issues that seem beyond normal side effects. Testing is also appropriate before starting Cefaclor if you have documented allergies to other antibiotics in the beta-lactam family. Additionally, if you need to reassess your allergy status over time—since some drug allergies can wane—this test provides updated information (Walk-In Lab 2024). Early detection of drug allergy helps avoid emergency situations and reduces associated medical costs.
How do I interpret the results?
Your results will indicate whether detectable levels of Cefaclor-specific IgE antibodies are present in your blood. Reference ranges vary by laboratory, but results are typically reported as positive (sensitization detected) or negative (no IgE-mediated allergy detected). A positive result means your immune system has produced IgE antibodies against Cefaclor, increasing your risk of allergic reaction upon exposure. However, clinical correlation is essential—some sensitized individuals may not experience symptoms, while severe reactions require immediate medical attention regardless of test results (Thermo Fisher 2024).
Negative
- Meaning: No IgE antibodies detected
- Action: Cefaclor generally safe; monitor for non-IgE reactions
Positive (Low)
- Meaning: Low-level IgE sensitization
- Action: Discuss with physician; consider alternative or careful monitoring
Positive (Moderate–High)
- Meaning: Significant IgE sensitization
- Action: Avoid Cefaclor; use alternative antibiotics; carry emergency medication
Approximately 79% of immediate Cefaclor hypersensitivity reactions present as anaphylaxis, underscoring the importance of accurate testing (NCBI 2014).
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No fasting or special preparation is required for this test. You can continue taking all medications, including antihistamines, as blood testing is not affected by these substances—unlike skin testing. Inform the laboratory staff of any current medications for documentation purposes. The test can be performed regardless of your skin condition, making it accessible even for patients with eczema, dermatitis, or extensive skin involvement (Thermo Fisher 2024). Simply visit your chosen lab location for a standard blood draw.
How often should I get tested?
Testing frequency depends on your clinical history and exposure risk. Generally, one test is sufficient to establish baseline allergy status, though follow-up testing may be warranted in specific circumstances.
- Initial allergy suspicion: Once to establish baseline
- After documented allergic reaction: Once for confirmation; retest not typically needed
- Reassessment of childhood allergy in adults: Every 3–5 years if clinically indicated
- Before planned Cefaclor treatment with uncertain history: One-time pre-treatment test
Why early detection matters
Identifying a Cefaclor allergy before exposure or early in treatment can prevent life-threatening anaphylaxis and other severe allergic reactions. Early detection reduces emergency room visits and hospitalization costs related to allergic reactions by up to 30%, improving both patient outcomes and healthcare efficiency (Johns Hopkins 2023). Knowing your allergy status empowers you and your healthcare providers to select safer antibiotic alternatives from the start, avoiding treatment delays and complications. Proper drug allergy identification also reduces the overuse of broad-spectrum antibiotics, which contributes to antibiotic resistance—a growing public health concern (CDC 2023).
Related tests you may consider
Penicillin V Allergy IgE Blood Test – Measures IgE antibodies to penicillin V and may help assess potential cross-reactivity with cephalosporins such as cefaclor.
Penicillin G Allergy IgE Blood Test – Measures IgE antibodies to penicillin G, which is clinically relevant due to potential cross-reactivity between penicillins and cephalosporins like cefaclor.
Total IgE Blood Test – Measures overall IgE levels to evaluate general allergic predisposition and provide context for specific drug allergy results.
