15.2 Minor Ailments II: Acne, Dermatitis, Psoriasis, Lice, Scabies & Sun Protection

Minor Ailments II: Acne, Dermatitis, Psoriasis, Lice, Scabies & Sun Protection

Skin conditions are visible and distressing, and many are managed with non-prescription products. Good outcomes depend on choosing the right agent and potency, and especially on counselling technique: how much to apply, where, how often and for how long.

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1. Acne Vulgaris

• Never use topical or oral antibiotics alone. Always combine them with BPO, which prevents Cutibacterium acnes resistance.
• BPO: start with 2.5 to 5% (as effective as 10%, with less irritation). It bleaches fabric and hair.
• Retinoids: apply a pea-sized amount at night to the whole affected area. Expect dryness and an initial flare. Results take 6 to 12 weeks. Use sunscreen. Topical tretinoin is avoided in pregnancy.
• Tetracyclines: take with a full glass of water, and stay upright for 30 minutes (esophagitis). Separate from calcium, iron and antacids. Photosensitivity. Avoid in pregnancy and under 8 years.
• Isotretinoin is highly teratogenic. Canadian monographs require a pregnancy prevention program: two forms of contraception, negative pregnancy tests before, during and after therapy, and usually no more than a 30-day supply at a time. Also monitor lipids, liver tests and mood. Avoid tetracyclines (raised intracranial pressure) and vitamin A supplements, and do not donate blood during treatment.

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2. Atopic Dermatitis (Eczema)

• Daily emollients are the foundation. Use thick, fragrance-free ointments or creams generously, within minutes of a short lukewarm bath ("soak and seal").
• Topical corticosteroids (TCS) treat flares. Match the potency to site and severity:

• Fingertip unit (FTU): the amount squeezed from the fingertip to the first crease, about 0.5 g. One FTU covers an area the size of two adult palms. Explaining FTUs counters "steroid phobia" and under-treatment.
• Ointments are more occlusive and more potent than creams of the same steroid.
• Long-term risks with misuse (skin atrophy, striae, telangiectasia) come from potent steroids on thin skin for long periods. They are not a reason to avoid appropriate use.
• Topical calcineurin inhibitors (tacrolimus, pimecrolimus) are steroid-sparing options for the face and folds. Expect transient burning at first.
• Moderate to severe disease: dupilumab, oral JAK inhibitors, or phototherapy, under specialist care.

3. Psoriasis and Contact Dermatitis

• Plaque psoriasis: a topical corticosteroid combined with a vitamin D analogue (calcipotriol/betamethasone), plus salicylic acid or coal tar for scale. Methotrexate, apremilast and biologics (IL-17, IL-23 or TNF inhibitors) are used for moderate to severe disease.
• Drugs that can worsen psoriasis: lithium, beta-blockers, antimalarials, and abrupt withdrawal of systemic steroids.
• Contact dermatitis: identify and avoid the irritant or allergen (nickel, fragrances, rubber, neomycin). Use a TCS of suitable potency, and refer widespread or facial reactions.

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4. Head Lice

• Treat only people with live lice, and check all household members.
• Options: permethrin 1% cream rinse, pyrethrins, or non-insecticidal products such as isopropyl myristate/cyclomethicone or dimeticone (physical action, so resistance does not develop). Most products need a second application 7 to 10 days later to kill newly hatched lice. Wet combing with a fine-toothed comb adds benefit.
• Environment:
  • Wash bedding, hats and towels used in the previous 2 days in hot water and dry on a hot cycle.
  • Items that cannot be washed can be sealed in a plastic bag for 2 weeks.
  • Not needed: steam-cleaning carpets, fumigating, bleaching surfaces, or cutting the hair.
• School: children may return after the first treatment. "No-nit" policies are not recommended.

5. Scabies

• Permethrin 5% cream:
  • Apply to the whole body from the neck down (including the scalp and face in infants and older adults), paying attention to the skin between fingers and toes, the wrists, under the nails, and the genitals.
  • Leave on for 8 to 14 hours, then wash off.
  • Repeat in 7 days.
• Treat all close contacts at the same time, even without symptoms.
• Wash bedding and clothing in hot water, or seal them in a bag for at least 3 days; mites do not survive long off the host.
• Itch can persist for 2 to 4 weeks after successful treatment. This is not treatment failure. Antihistamines or a mild TCS can help.
• Oral ivermectin is used for crusted scabies or outbreaks.

6. Sun Protection and Photosensitivity

• Sunscreen: a broad-spectrum product with SPF 30 or higher, applied generously 15 minutes before exposure and reapplied every 2 hours and after swimming or sweating. Use shade and protective clothing too.
• Infants under 6 months should be kept out of direct sun rather than relying on sunscreen.
• Photosensitizing drugs need extra protection: tetracyclines, fluoroquinolones, sulfonamides, thiazides, amiodarone, retinoids and some NSAIDs.