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Contact Sensitizers (Immunotherapy) for Warts


Generic NameBrand Name
dinitrochlorobenzene (DNCB)
diphencyprone (DCP)
squaric acid dibutyl ester (SADBE)

How It Works

Contact sensitizers are a form of immunotherapy. Immunotherapy triggers your immune system to kill the virus causing the wart. This destroys the wart.

Two steps are required to trigger your body's immune system with a contact sensitizer:

  • The contact sensitizer is put on a small area of your arm or back. Your skin should become red, swollen, itchy, or blistered. This kind of skin reaction is a sign that the contact sensitizer will work. The next time the sensitizer is applied to your skin, your body's immune system will react to it, and the affected area will develop an allergic (immune) reaction.
  • After a few days, the same sensitizer is applied to the wart (diluted for common warts and concentrated for plantar warts). Repeat treatments with increasingly concentrated sensitizer are made every week or so until the immune reaction has cleared the wart.

Why It Is Used

Contact sensitizers are sometimes used to treat warts that have been resistant to other treatments.

How Well It Works

One review of studies reports that DNCB removed warts in 80% of the people using it compared to 38% in people using a placebo.1 Talk to your doctor about how well his or her choice of contact sensitizers has worked in clinical practice.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Callor other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.

A severe allergic reaction can occur with contact sensitizer treatment.

Call your doctor if you have:

  • Hives.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Contact sensitizers are not widely used because they are highly potent and expensive and require careful handling to avoid causing unintended allergic reactions.

Contact sensitizers are not often used with children.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

Do not use this medicine if you are pregnant, breast-feeding, or planning to get pregnant. If you need to use this medicine, talk to your doctor about how you can prevent pregnancy.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)Click here to view a form.(What is a PDF document?) to help you understand this medication.



  1. Loo SK, Tang WY (2009). Warts (non-genital), search date June 2008. Online version of BMJ Clinical Evidence:


ByHealthwise Staff
Primary Medical ReviewerPatrice Burgess, MD - Family Medicine
Specialist Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Last RevisedSeptember 7, 2012

eMedicineHealth Medical Reference from Healthwise

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