There is no definite medical treatment for the molluscum contagiosum virus (MCV) itself, but there are some options to clear up the papules (raised bumps on the skin). When the virus' host is immunocompetent (able to develop an immune response, as opposed to someone HIV-positive or someone who has received an organ transplant), the lesions usually begin to disappear after three to four months, but they may continue to be present for three to five years. Most people desire treatment for cosmetic purposes, but the virus tends to be more persistent and disfiguring in individuals with weakened immune systems. Also, around 7% of papules will leave a scar when left to heal naturally. There is debate in the medical community as to whether any treatment has been proven to be effective. In cases where treatment is effective, it often requires multiple rounds and/or risks scarring.
In HIV-positive patients, taking antiretrovirals (drugs that fight retroviruses, including HIV) to manage HIV can make separate treatment of MCV more effective, or even cause the papules to clear up without additional treatment.
One can apply 0.7 to 0.9% liquid cantharidin (the extract of the blister beetle) to the papules then wash it off after two to six hours. There is a small risk of scarring or of extreme reactions to the extract, so patients and their families should be made aware of these risks. Many also find it painful. It should not be used on the genital areas or face for these same reasons.
An antiviral agent, Cidofovir may be effective if applied either directly to the papule as a cream with a 3% concentration or injected into the lesion (skin abnormality). It may be particularly effective in the treatment of hosts with weakened immune systems. Studies have found it to clear the papules in two to six weeks, but its potential to cause cancer and high cost have somewhat limited its use.
In cases where the papules are extensive, cimetidine, a medication normally used to treat gastric issues and in dermatology to treat warts, may be taken orally. There is some evidence that 40mg per kilogram of a person's weight per day, divided between two daily doses for two months may be quite effective, but the authors of the study demonstrating this suggest more research into the matter. Cimetidine interacts with several other medications, so great care must be taken in reviewing which medications a patient takes.
Cryosurgery, or cryotherapy, is an efficient, quick, and common method of treating papules. The doctor applies Frigiderm (a skin refrigerant and anaesthetic), dry ice, or liquid nitrogen to each papule for a few seconds. The formation of followed by the thawing of ice in the cells kills the tissue. Downsides to the treatment include the facts that multiple visits at two to three week intervals may be necessary to destroy all the papules and that scarring and darkening or lightening of the skin may occur as a result. The process is painful despite the use of local anaesthetics (products that ease pain).
Curettage involves scraping the papules off the surface of the skin. It can be quite effective, but it is also painful despite the use of local anaesthetics. This renders it more suitable for the treatment of adults than children. It can be useful in that it provides a sample to be analyzed in a lab as well as removing the lesion. It can be combined with electrodessication, a process where the tissue is killed with an electrical current, when papules are large. A layer of the papule is burnt and then scraped away with the curette, and the process is repeated. Multiple treatments may be necessary when the papules have extended from the skin to the fat.
Imiquimod, a skin and mucous membrane agent, can be applied in a 5% concentration three to five times a week for a one to three month period. Although it is not known exactly how, imiquimod stimulates the immune system, allowing the body's cells to fight the virus. One of the benefits of this treatment is that little scarring is associated with it.
A pulsed dye laser, a type of device that produces a bright light that is absorbed by abnormal blood vessels, destroying them without damaging surrounding skin, is used to resolve the lesions. It is quick, efficient, and effective, with no scarring and little to no lightening or darkening of the skin. Up to 99% of the papules can be destroyed in a single treatment, though multiple treatments may be necessary when the papules have extended from the skin to the fat. It is very expensive however. It becomes an option when papules are very large.
One can dip a sharp instrument in phenol, an antiseptic, to burst the papules. It is also, according to one study, more likely to cause scarring than squeezing the core from the papule (which is just as effective).
Podofilox, a purified form of the main ingredient in podophyllin (see below) may be used at home as it is safer than podophyllin. Usually, 0.05 ml of 5% podofilox is applied twice daily for three days. It is unknown what effects it could have on an unborn or nursing child, so women who are pregnant or nursing should not use it. Women needing it should be on a reliable form of birth control.
This resin is a keratolytic agent (thins skin and causes it to loosen and fall off). It should only be administered by a healthcare professional. A 25% concentration in a tincture of alcohol or benzoin can be applied weekly. After one week, any resistant or new papules can be treated in the same way. However, they should be covered in tape after treatment and the tape must be removed after six to eight hours. It can cause severe damage to normal skin adjacent to the papule which can cause scarring and other side effects, so care must be taken to protect surrounding skin.
There is considerable debate regarding the effectiveness of potassium hydroxide in treating Molluscum Contagiosum. One study applied 10% potassium hydroxide twice a day to all the papules until a superficial ulcer appeared or inflammation occurred and they found resolution came about in a mean of thirty days. There were complications such as darkening or lightening of the skin and scarring. Another study found 5% potassium hydroxide was just as effective with fewer side effects, but another found it no more effective than a placebo (a "fake" treatment given to compare results with actual treatment).
Tretinoin, a 0.1% cream (though 0.5% creams have been effective as well) or a 0.025% gel can be applied to the papules with the rough end of a broken toothpick. The goal is to gently irritate the lesions to cause an inflammatory response, which will be supplemented with that caused by the retinoid. This should trigger the body to heal the papule. This should be done every few days until the lesions regress. Side effects include some mild redness.
Salicylic acid is also used to treat warts and acne. It is reported to sting more than some other topical treatments, but is less painful than cryosurgery or curettage, so may be a better option for children. In one study, a concentration of 12% was used mixed with a base. Some also recommend covering the papules with tape during the treatment.
Silver Nitrate Paste
Silver nitrate should only be applied at the doctor's office, but it appears to be highly effective (one Japanese study of over three hundred fifty patients found a nearly 98% success rate with no scarring). A paste of 40% silver nitrate mixed with flour is applied to the affected area, which has first been prepared with a cream to prevent minor itching and pain. A very few people do report severe itching or some pain.
Tape stripping can be done at home. An adhesive tape is applied to the affected areas at bedtime then removed in the morning, taking with it the top layers of the skin and hopefully the infective core. Use of the same piece of tape, however, can spread the virus to previous unaffected areas and care must be taken in handling the tape following use.
Trichloroacetic Acid is a keratolytic agent that erodes the skin. It is applied by a healthcare provider to the papule until a white "frost" appears, taking care not to touch the surrounding skin (which may be covered in petroleum jelly) as it is a caustic agent (capable of destroying living tissue). There is little report of change in pigmentation or significant irritation. It can be (cautiously) used on the face and/or for children. There is a mild stinging sensation associated with the treatment, so the medical professional should try to treat as many of the lesions as the patient will tolerate.