What is a topical steroid?
Steroids are naturally occurring chemicals, produced mainly by the adrenal glands, the small glands located on top of each kidney. The steroids used as medications are a man-made version of the hormones produced by the adrenal glands. There are different types of steroids, and the type most commonly used to treat skin problems is known as a corticosteroid.
Topical steroids are preparations applied directly to the skin to reduce inflammation and irritation. They are generally used when other measures such as emollients are ineffective.
Several forms are available for topical steroids, intended to suit the type of skin lesion and its location. Creams are general purpose and are the most popular form. Ointments are most suitable for dry, non-hairy skin. The gel and lotions are useful in hair-bearing skin.
How does a topical steroid work?
Topical steroids work by reducing the inflammation caused by conditions such as psoriasis and eczema. They are absorbed into the skin cells and stop these cells from producing various inflammation-causing chemicals. These chemicals cause blood vessels to widen and other inflammatory substances to arrive, resulting in the affected area of skin becoming red, swollen and itchy. By preventing these inflammatory chemicals from being released in the skin, corticosteroids reduce inflammation and relieve its related symptoms such as itchiness.
Topical steroids are a cornerstone in the treatment of eczema, psoriasis and many other skin diseases but are not a cure as they have no effect on the underlying cause of inflammation. They can, however, be very effective in helping to control skin flare-ups and relieve symptoms, such as itching and irritation. Also, they help reduce the likelihood of infection that may occur as a result of scratching and trauma to the skin.
How to use topical steroids?
Always follow your doctor's instructions. Generally, a topical steroid is applied once daily to inflamed skin for a course of few days to several weeks.
If you're using both topical corticosteroids and emollients, you should apply the emollient first. Then wait about 30 minutes before applying the topical corticosteroid.
Sometimes, the amount of medication you're advised to use will be given in fingertip units (FTUs).
A FTU is the amount of medication needed to squeeze from a tube on a line from the tip of the index (second) finger to the first crease of the finger. It should be enough to treat an area of skin double the size of the flat of your hand with your fingers together.
What are the risks involved in using a steroid cream?
When used correctly, topical steroids rarely cause significant side effects. However, if higher potency preparations are used for excessive periods, they may cause changes to the treated skin, including thinning, bruising, stretch marks, and loss of skin pigment at the site of application. Occasionally, an allergy to the steroid or to one of the other constituents of the topical preparation may develop, and cause more inflammation.
Topical steroid can favour, aggravate or mask skin infections such as impetigo, tinea (fungal infection), herpes simplex and folliculitis. However, topical steroids combined with an appropriate antibiotic remain the first-line treatment for infected eczema.
Topical steroid should be used cautiously on eyelid skin, where it could potentially result in periocular dermatitis. Excessive use on the eyelids over weeks to months might lead to glaucoma or cataracts.
If applied in large quantities, on an extensive area and for a prolonged period, the steroids can be absorbed into the blood system and cause internal side effects, e.g. suppressing the adrenal glands (this is very rare, occurring mostly because of over the counter sales of corticosteroids in countries where that is permitted).
This is not a full list of all the possible side effects. For more information on side effects, see the leaflet that comes with your medication.