What is salicylic acid?
Salicylic acid belongs to a group of medicines known as keratolytics. It is used in the treatment of scaly skin diseases where the skin has become thickened, scaly and flaky. Topical preparations of salicylic acid, either alone or in combination with other medicines, can be used to treat the following common scaly skin conditions:
- Viral warts
- Seborrhoeic dermatitis
- Chronic atopic dermatitis
- Lichen simplex
How does salicylic acid work?
Salicylic acid works by softening keratin, a protein that forms part of the skin structure. This helps to loosen dry scaly skin making it easier to remove. When salicylic acid is used in combination with other medicines it takes off the upper layer of skin allowing the additional medicines to penetrate more effectively.
In acne, topical salicylic acid helps slow down shedding of the cells inside the follicles, preventing clogging. Salicylic acid also helps break down blackheads and whiteheads.
Salicylic acid preparations
Salicylic acid preparations come in many forms and strengths. Available dosage forms include cream, gel, lotion, ointment, pads, plaster, shampoo, cleanser and topical solution. Strengths of salicylic acid preparations range from 0.5% up to 30%. The form and strength chosen depends on the condition that is being treated.
Listed below are a few of the many salicylic acid preparations available in New Zealand.
|Salicylic acid 2-3%, Betamethasone 0.05% (Diprosalic®)
|Salicylic acid 15-27% (Duofilm®)
|Salicylic acid 2%, Coal tar solution 12%, Sulphur 4% (Coco-Scalp®)
|Seborrhoeic dermatitis Dandruff
|Salicylic acid 0.5% oil-free acne wash (Neutrogena®)
Whilst many salicylic acid preparations are available from a pharmacy, some preparations are only available on a doctor's prescription. These include preparations containing a combination of salicylic acid and topical corticosteroid, e.g. Diprosalic®.
How to use salicylic acid preparations
- It is very important that you use preparations strictly as directed on the label. Do not use more of it, do not use it more often, and do not use it for a longer time than recommended. Failing to follow instructions may lead to increased absorption through the skin and salicylic acid poisoning.
- Avoid contact with eyes and other mucous membranes, such as the mouth, inside of the nose, and genitals. Accidental application to areas should be flushed immediately with water for 15 minutes.
- Do not use on irritated skin or on any area that is infected or reddened.
- Protect areas surrounding the affected area by applying petroleum jelly around the periphery of the area to be treated.
- Unless your hands are being treated, wash them immediately after applying this medicine.
Side effects of topical salicylic acid preparations
Salicylic acid preparations are usually well tolerated. Mild stinging may occur especially on broken skin and when higher concentrations are used. Salicylic acid can irritate or burn healthy skin so it is important to keep the medicine confined to the affected area(s). Check with your doctor if you experience:
- Moderate or severe skin irritation (particularly if not present before use of this medicine)
- Unusually warm skin and reddening of skin.
True allergy to topical salicylic acid is rare, however serious reactions including anaphylaxis have been reported.
Salicylic acid poisoning (overdose) with topical preparations is rare. Symptoms of poisoning include confusion, diarrhoea, nausea, vomiting, dizziness, headache, rapid breathing, continuing ringing or buzzing in ears, severe drowsiness.
Precautions when using topical salicylic acid preparations
When using salicylic acid preparations do not use any of the following preparations on the affected area, unless directed to do so by your doctor:
- Alcohol containing preparations
- Any other medicated topical agents, e.g. benzoyl peroxide, topical retinoids, calcipotriol
- Abrasive soaps and cleansers
- Cosmetics or soaps that dry the skin or are designed to peel/exfoliate.
Inform your doctor if you are pregnant or breast-feeding. Salicylic acid can be absorbed through the mother's skin. The risks and benefits will need to be discussed with your doctor before using any preparations containing salicylic acid.
Salicylic acid preparations should not normally be used in children younger than 2 years. Use in young children should be monitored carefully as children are more likely to get skin irritation and the absorption through skin is greater.