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Posted By: Kristine Kucera, PA-C, MPAS, DHS
May 19, 2020
Since their introduction in early 1950s, topical corticosteroids (TCS) have become the drugs most commonly prescribed by dermatologists for outpatients and are considered the mainstay of treatment for many skin conditions. If used appropriately, they are safe and effective, and side effects are rare. However, long-term use, misuse, and abuse by practitioners and patients can lead to complications.
The mechanism of action of corticosteroids is anti-inflammatory, immunosuppressive, and anti-mitogenic. Therefore, they are effective for skin conditions that are characterized by hyperproliferation, inflammation, and immunologic involvement. These dermatoses include psoriasis, eczema, atopic dermatitis, contact dermatitis, lichen planus, alopecia, vitiligo, discoid lupus, insect bites, and many more. Successful treatment with TCS includes making an accurate diagnosis; selecting the correct drug; and keeping in mind the potency, delivery vehicle, frequency of application, duration of treatment, and adverse effects.
It is important to keep in mind how the vehicle can influence potency and the amount of steroid released into the skin. For example, ointments are the most potent because they are the most occlusive; therefore, they should be used on dry and thicker skin conditions. Creams are the next most potent and are best used on moist or weeping lesions. Gels or lotions are best in flexural and hair-bearing areas, and foams for the scalp and body have proven to be a cosmetically acceptable vehicle.
Potential adverse effects of TCS include skin atrophy, striae, purpura, acne, perioral dermatitis, hypertrichosis, vasoconstriction, hypopigmentation, and allergic contact dermatitis. Contraindications include bacterial, viral, or mycotic infection—including scabies, molluscum, eczema herpeticum, and pityriasis rosea—and pregnancy or lactation.
Avoiding overuse by knowing how much to prescribe and how many refills are warranted is an easy way to avoid the commonly observed complication of steroid-induced skin atrophy and striae. Fingertip units are a convenient way to measure the amount of cream that should be prescribed to a patient. One unit is the amount of cream fitting onto the end of the finger, which is usually equal to 0.25 grams. For an adult, the amount of cream that should be used depends on the body part:
- One hand: apply 1 fingertip unit
- One arm: apply 3 fingertip units
- One foot: apply 2 fingertip units
- One leg: apply 6 fingertip units
- Face and neck: apply 2.5 fingertip units
- Trunk, front and back: 14 fingertip units
- Entire body: about 40 units
By using the above information and considering that TCS are normally applied twice daily to the affected area for up to 2 weeks, you can determine the appropriate quantity and number of refills that a patient should be prescribed.
- American Academy of Dermatology. www.aad.org. Accessed May 8, 2020.
- Dermnet NZ. Fingertip unit. www.dermnetnz.org/topics/fingertip-unit/. Accessed May 8, 2020.
- Kragballe K. Topical corticosteroids: mechanisms of action. Acta Derm Venereol Suppl (Stockh). 1989;151:7-10.
- Rathi SK, D'Souza P. Rational and ethical use of topical cortiocosteroids based on safety and efficacy. Indian J Dermatol. 2012;57:251–259.
Filed under: Dermatology