He said that this is because it is often difficult to separate the hair from the scalp when applying the medicine. This may end up being messy.

Sometimes, the medication may get stuck to the hair, hindering its absorption.

Plaque psoriasis can also affect the rest of the body. Apart from the scalp, it is most commonly found on the elbows, knees and lower back.

Psoriasis can affect the nails and joints too. Psoriatic arthritis, or painful inflammation of the joints, can strike and may leave a person's fingers and toes disfigured.

For body psoriasis, different treatment options include topical steroids to reduce inflammation, vitamin D derivatives to decrease cell turnover rate and ultraviolet light treatment to slow down cell division rate.

Psoriasis stays with a person for life and has no cure.

However, with effective treatment and appropriate lifestyle changes, it may clear for months or even years, said Dr Aw.

To manage the condition through lifestyle changes, try and avoid psoriasis triggers. Reduce stress, exercise regularly and do not smoke.

Remember to use a moisturiser regularly too, said Dr Tham Siew Nee, a dermatologist at Gleneagles Medical Centre.

As skin cells multiply and die faster than usual in patients, skin tends to become thick and dry. Studies have repeatedly shown that the regular application of a moisturiser can improve psoriasis in at least one-third of patients, she said.

For psoriasis of the body, the moisturiser should be applied immediately after a shower so that the moisture is kept in, she added.

lingg@sph.com.sg

This article was first published in Mind Your Body, The Straits Times.