Molluscum contagiosum is a common condition where small warty bumps (mollusca) appear on the skin. It is caused by a virus that can be passed on by skin contact or from contaminated towels, flannels, soft toys, etc. It is not serious and usually clears within 12-18 months without any treatment.
What does molluscum contagiosum look like?
The skin develops small lumps (mollusca) which are pearly-white or slightly pink. Each lump (molluscum) looks like a small swelling on the skin and is round, firm and about 2-5 mm across. A tiny dimple often develops on the top of each molluscum. If you squeeze a molluscum, a white cheesy fluid comes out. In most cases fewer than 30 mollusca develop.
Sometimes many mollusca develop over various parts of the skin. They tend to occur in groups or clusters. Any part of the body can be affected but it is rare on the palms and soles.
What causes molluscum contagiosum?
It is caused by a virus which can be passed on by skin-to-skin contact. You can also be infected by touching things that have been contaminated by the virus. For example, by sharing towels, flannels or soft toys that have been used by someone who has molluscum contagiosum. Once one area of skin is affected the rash can spread to other areas of your skin. However, most people are resistant (immune) to this virus. Therefore, most of those who come into contact with affected people do not develop molluscum contagiosum.
In adults sometimes the virus is passed on during the close skin-to-skin contact of having sex. If it is passed on whilst having sex then the first mollusca to appear tend to be on the skin of the lower tummy (abdomen) and around the penis, vagina or back passage (anus). If this occurs then you should consider being checked out for other sexually transmitted infections. You can attend a genitourinary medicine (GUM) clinic for tests and do not need a referral from your GP.
Who gets molluscum contagiosum?
Molluscum contagiosum can affect anyone of any age. It is most common in children and mostly happens in children aged 1-4 years. However, it can also (much less commonly) affect adults. People whose immune systems are not working as well as usual are more likely to get it. (For example, people with AIDS, or people who are having chemotherapy or steroid treatment.)
How does molluscum contagiosum develop?
The small lumps (mollusca) on the skin usually develop 2-8 weeks after you become infected with the virus. Typically, each lump (molluscum) lasts a few weeks or months, crusts over and then goes. However, new ones tend to appear as old ones are going, as the virus spreads to other areas of skin. Therefore, crops of mollusca may appear to come and go for several months.
It commonly takes 12-18 months before the last of the mollusca goes completely. Occasionally, the condition lasts longer than two years - sometimes as long as five years. For some people, the main concern is that the mollusca can look unsightly. Most children are not bothered by it.
Is molluscum contagiosum serious?
The small lumps (mollusca) on the skin are not usually itchy, painful, or serious. A scar is not usually left when they go but sometimes a tiny dent or mark remains. In a few people the skin looks lighter in the places where mollusca have been. Occasionally, the skin next to a lump (molluscum) becomes infected with germs (bacteria). This can be treated with antibiotic creams or medicines. Rarely, a molluscum on an eyelid causes eye inflammation. (See a doctor if any eye symptoms develop related to a molluscum.) After an episode of molluscum contagiosum has cleared away, you will normally be immune to the virus and further episodes only occur rarely.
If you develop a very large number of mollusca (hundreds) or the mollusca are larger than normal, it could be a marker of an underlying problem with your immune system. This may need specialised assessment.
Can infection with molluscum contagiosum be prevented?
The chance of passing on the molluscum contagiosum virus to others is small, and it is not serious anyway. Therefore, there is no need to keep children with molluscum contagiosum off school, or away from swimming pools, etc. There is no need for adults to keep away from gyms or other people.
To reduce the chance of passing it on to others, it is sensible not to share towels, clothes, soft toys, or bathwater if you have molluscum contagiosum. Also, try to avoid skin-to-skin contact with other people (for example, by covering affected areas with clothing). For adults who have the small lumps (mollusca) on the skin, a condom should be used during sex. This will not completely stop skin-to-skin spread but will reduce the chance of passing it on considerably.
Try not to scratch the mollusca, as this may increase the risk of spreading the rash to other areas of the skin. Molluscum contagiosum can be passed on to other people (is contagious) until the last lump (molluscum) has gone.
What is the treatment for molluscum contagiosum?
It is usually best not to treat, particularly in children
This is because:
- The small lumps (mollusca) on the skin will usually go away without treatment within 12-18 months. Having the rash does not limit your activities such as going to school, sports, swimming, etc.
- Many of the treatments can be painful (such as liquid nitrogen).
- Some treatments have a risk of burning the surrounding skin.
- All treatments have a small risk of scarring the skin. Scarring rarely occurs if the mollusca are left to go away on their own.
- There is no really good evidence that any treatment makes a big difference to how long the mollusca last.
Treatment options if needed
- There is no convincing evidence yet that any one treatment works best.
- Sometimes treatment is wanted, if the lesions are particularly unsightly or troublesome, or if they are spreading very widely. You should discuss this with your GP.
- Sometimes mollusca are frozen with liquid nitrogen (cryotherapy).
- Creams and lotions may be used. As previously stated, so far doctors are not sure which is the best one, or even if some of them have any effect at all. Options used include:
- Benzoyl peroxide.
- Hydrogen peroxide.
- Potassium hydroxide.
- Iodine preparations.
- Imiquimod cream. (Prescribed occasionally by skin specialists particularly in people who have problems with their immune system.)
- Pulsed dye laser therapy. (Blasting the mollusca with special laser beams. Occasionally used by skin specialists.)
- If the skin around the mollusca becomes itchy or infected, your GP can prescribe creams for this.
Dr Tim Kenny
Dr Mary Harding
Dr Helen Huins