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How It Works

Imiquimod is thought to work by helping the body's immune system produce interferon and similar substances that attack abnormal cells, viruses, and cancerous cells.2

Imiquimod is a cream available by prescription. It can be applied at home. Your doctor will show you how to apply imiquimod.

Why It Is Used

Imiquimod may be the medicine treatment your doctor recommends first for external genital warts. It may shrink the warts.

Imiquimod is approved to treat genital warts, actinic keratosis, and superficial basal cell carcinoma.

Imiquimod may be used to treat basal cell carcinomas when surgical methods cannot be used.

Imiquimod can be used for difficult-to-treat common warts.

It is not known whether imiquimod is safe to use during pregnancy or on children younger than 12. Health Canada's Therapeutic Products Directorate (TPD) has approved imiquimod for those age 18 and older.

How Well It Works

Genital warts

Studies report:

  • Many genital warts go away within 4 months of treatment.2
  • Imiquimod 5% cream is more effective than 1% cream for genital warts.2

After using imiquimod, there is up to a 20% chance the warts will come back.3

Basal cell carcinoma

Studies show that more than 75% of superficial basal cell carcinomas cleared when imiquimod cream was applied. Imiquimod may prove to be beneficial in treating large, superficial basal cell carcinomas on the trunk of the body, where surgical treatment can cause severe scarring.1

Common warts

Whether imiquimod is an effective treatment for common warts is not yet known.

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.

Call 911 or other emergency services right away if you have:

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

Call your doctor if you have:

  • Blisters on your skin.
  • Severe itching in genital or other skin areas.
  • Open sores or scabs on skin.
  • Severe redness of skin.
  • Scaling of skin.
  • Flu-like symptoms, including diarrhea, fatigue, fever, headache, or muscle pain.

Common side effects of this medicine include:

  • Mild burning or stinging of skin.
  • Flaking of skin.
  • Mild soreness or tenderness of skin.
  • Rash.
  • Mild redness of skin.
  • Swelling of area where medicine was applied.
  • Lightening of skin colour.

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

What To Think About

Wash your hands after applying imiquimod cream, because it may cause skin irritation.

Avoid sexual contact while you are using imiquimod cream for genital warts. Wash the cream off of your skin before you have any sexual contact. The cream may weaken condoms and diaphragms. It also may irritate your partner's skin or may rub off during sex.

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

If you are pregnant, breast-feeding, or trying to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


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) (What is a PDF document?) to help you understand this medication.



  1. U.S. Food and Drug Administration (2004). FDA approves new use of drug to treat superficial basal cell carcinoma, a type of skin cancer. Available online:
  2. Buck HW Jr (2007). Warts (genital), search date February 2007. Online version of BMJ Clinical Evidence. Also available online:
  3. American College of Obstetricians and Gynecologists (2005, reaffirmed 2009). Human papillomavirus. ACOG Practice Bulletin No. 61. Obstetrics and Gynecology, 105(4): 905–918.


By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Primary Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer Jeanne Marrazzo, MD, MPH - Infectious Disease
Last Revised August 27, 2010

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.