Schick Test Principles and Procedure
Understand the Schick test, its principles, and procedure. Learn how this test helps determine immunity to diphtheria through a simple intradermal injection.
Written by Dr. Siri Nallapu
Reviewed by Dr. Dhankecha Mayank Dineshbhai MBBS
Last updated on 29th Aug, 2025
When it comes to protecting ourselves from infectious diseases, medical tests play a crucial role in diagnosis and prevention. One such test is the Schick Test, which helps determine a person’s immunity to diphtheria, a serious bacterial infection. If you or your child have been advised to take this test, you might have questions about how it works and why it’s important.
In this article, we’ll explain the principles, procedure, and significance of the Schick Test in simple terms, so you can feel informed and at ease.
What Is the Schick Test?
The Schick Test is a skin test used to check whether a person has enough immunity against diphtheria toxin—a harmful substance produced by the bacteria Corynebacterium diphtheriae. Diphtheria is a contagious disease that affects the throat and can lead to severe breathing difficulties, heart problems, and even death if untreated.
This test helps doctors decide if a person needs a booster dose of the diphtheria vaccine or if they are already protected.
Why Is the Schick Test Done?
The test is mainly used in:
- Children and adults who may not have been fully vaccinated against diphtheria.
- Healthcare workers or travellers visiting regions where diphtheria is still common.
- People with uncertain vaccination history to confirm immunity.
Since diphtheria is rare in countries with strong vaccination programs, the Schick Test is not commonly performed today. However, it remains useful in certain situations where immunity needs verification.
Consult Top Specialists
How Does the Schick Test Work?
The test is based on the body’s immune response to diphtheria toxin. Here’s how it works:
1. Diphtheria Toxin vs. Toxoid:
- A small amount of purified diphtheria toxin is injected into the skin.
- A control injection (heat-treated toxin, which is harmless) is also given for comparison.
2. Immune Reaction Check:
- If a person lacks immunity, the toxin will cause a red, swollen reaction at the injection site within a few days.
- If a person has immunity, their body neutralises the toxin, and no reaction occurs.
3. Interpreting Results:
- Positive Reaction (No Immunity): Redness and swelling at the toxin site but not at the control site.
- Negative Reaction (Immune): No reaction at either site.
- Pseudo-Reaction (Allergic Response): Redness at both sites due to sensitivity, not lack of immunity.
What Happens During the Schick Test?
If your doctor recommends the Schick Test, here’s what you can expect:
Before the Test
- No special preparation is needed.
- Inform your doctor if you have allergies or skin conditions.
During the Test
1. A healthcare provider will clean your forearm with an antiseptic.
2. Two small injections are given:
- Test Solution: Contains diphtheria toxin.
- Control Solution: Contains inactivated toxin.
3. The injections are shallow (just under the skin) and cause minimal discomfort.
After the Test
You can resume normal activities.
- Avoid scratching or rubbing the injection sites.
- Results are checked after 48 to 96 hours (2-4 days).
Possible Side Effects
- Mild redness or swelling (normal if you lack immunity).
- Rarely, slight fever or discomfort.
What Do the Results Mean?
How Can You Protect Yourself from Diphtheria?
Since the Schick Test checks immunity, the best way to stay protected is through vaccination:
- DTaP Vaccine (for children) – Protects against diphtheria, tetanus, and whooping cough.
- Tdap/Td Booster (for teens and adults) – Ensures continued immunity.
Additional Preventive Measures:
- Maintain good hygiene (frequent handwashing).
- Avoid close contact with infected individuals.
- Ensure children receive all recommended vaccine doses.
When to See a Doctor?
Consult a healthcare provider if:
- You or your child missed diphtheria vaccinations.
- You’re travelling to an area where diphtheria is common.
- You notice symptoms like sore throat, fever, or difficulty breathing (possible diphtheria infection).
Need a vaccination or immunity check?
You can easily book a consultation or schedule a test through Apollo 24|7 for expert advice and care.
Conclusion
The Schick Test is a simple yet effective way to check immunity against diphtheria. While it’s not commonly used today due to widespread vaccination, it remains valuable in certain cases. If you’re unsure about your immunity status, speak to your doctor about vaccination and preventive measures.
Consult Top Specialists
Consult Top Specialists
Dr. Harshendra Jaiswal
General Physician/ Internal Medicine Specialist
12 Years • MBBS , MD (General medicine)
Kolkata
108 DHANA DHANVANTARI Clinic, Kolkata
(25+ Patients)
Dr. Swagata Sircar
General Physician/ Internal Medicine Specialist
8 Years • MBBS, MD General Medicine
Kolkata
HealthYou Speciality Clinic & Diagnostics., Kolkata
Dr. Dhanraj K
General Physician/ Internal Medicine Specialist
25 Years • MBBS, MD Internal Medicine - Osmania Medical College, Hyderabad
Hyderabad
Apollo Hospitals Jubilee Hills, Hyderabad
(375+ Patients)
Dr. Anand Ravi
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Swarna Deepak K
General Physician/ Internal Medicine Specialist
17 Years • MBBS: MD (Internal Medicine) MRCP (UK), EDIC (European Diploma in Critical Care), IDCCM, IFCCM (Critical Care), FID (Royal Liverpool Academy)
Hyderabad
Apollo Hospitals Jubilee Hills, Hyderabad
(375+ Patients)
Consult Top Specialists
Dr. Harshendra Jaiswal
General Physician/ Internal Medicine Specialist
12 Years • MBBS , MD (General medicine)
Kolkata
108 DHANA DHANVANTARI Clinic, Kolkata
(25+ Patients)
Dr. Swagata Sircar
General Physician/ Internal Medicine Specialist
8 Years • MBBS, MD General Medicine
Kolkata
HealthYou Speciality Clinic & Diagnostics., Kolkata
Dr. Dhanraj K
General Physician/ Internal Medicine Specialist
25 Years • MBBS, MD Internal Medicine - Osmania Medical College, Hyderabad
Hyderabad
Apollo Hospitals Jubilee Hills, Hyderabad
(375+ Patients)
Dr. Anand Ravi
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Swarna Deepak K
General Physician/ Internal Medicine Specialist
17 Years • MBBS: MD (Internal Medicine) MRCP (UK), EDIC (European Diploma in Critical Care), IDCCM, IFCCM (Critical Care), FID (Royal Liverpool Academy)
Hyderabad
Apollo Hospitals Jubilee Hills, Hyderabad
(375+ Patients)
