Dark knees, elbows and underarms

What it is

Darker skin on the knees, elbows, knuckles, underarms, neck and inner thighs is very common. It may be due to friction, dryness, shaving or, in some cases, a condition called acanthosis nigricans, where skin becomes dark, thick and velvety.

How it works

Darker knees, elbows and underarms are usually caused by friction and pressure, which thickens skin and stimulates pigment. In acanthosis nigricans, high insulin levels stimulate skin cells, causing velvety dark skin, often on the neck and underarms.

Why it matters on darker skin

Pigment cells in darker skin respond to rubbing and inflammation. Acanthosis nigricans is more common in darker skin and is linked to insulin resistance, overweight and type 2 diabetes risk.

Causes and triggers

Friction, kneeling, shaving and deodorant irritation, weight gain, insulin resistance and some hormone conditions.

What helps — and why it works

Reduce friction with loose clothing and gentle moisturising. Avoid shaving irritation in the underarms. Gentle ingredients such as urea or lactic acid creams and niacinamide may help. If acanthosis nigricans is present, healthy weight, activity and diet changes treat the cause and can improve the skin. Reduce friction and irritation: less stimulus for pigment. Expected timeline: months. Moisturise; urea or lactic acid for rough skin: smooths and softens thickened skin. Expected timeline: 4–8 weeks. Check blood sugar if velvety patches: acanthosis can be the first sign of insulin resistance.

What to avoid and why

Avoid scrubbing, lime juice, bleaching creams and harsh deodorants on irritated skin.

Common mistakes

• Scrubbing hard or using lemon and bleach.
• Lightening creams.

Body care basics in a hot climate

Heat and humidity mean the body sweats more, which feeds the bacteria and yeasts that cause odour, rashes and some types of body acne. A daily lukewarm shower with a gentle, soap-free or mild cleanser, thorough drying of skin folds and between toes, and fresh, breathable cotton clothing prevent many problems. Moisturise straight after bathing while skin is still damp so water is sealed in; this matters even in humid months because frequent washing strips natural oils, and it matters most during harmattan. Avoid sharing towels, razors and sponges, which spread fungal and bacterial infections. When shaving, use a sharp blade, shave with the grain and do not stretch the skin; for curly hair a guarded trimmer is often better. Be cautious with body-lightening, 'carrot' or 'toning' lotions: many contain undeclared steroids or mercury. If a rash spreads, keeps coming back, or appears with fever, see a doctor rather than trying more creams.

Choosing body products

For most people an unscented, gentle cleanser and a plain moisturiser are enough. Antiperspirants containing aluminium salts are the most effective way to reduce sweating and are best applied at night to dry skin. Fragranced body sprays and deodorants are a common cause of allergy; fragrance-free options are kinder to sensitive skin. Aerosol products are easy to over-apply and some have been recalled for benzene contamination, so roll-ons and creams are a sensible default. For fungal rashes, plain antifungal creams such as clotrimazole are better than combination creams containing strong steroids, which can make infections spread. Always check for a NAFDAC number and a full ingredient list.

Questions to ask your doctor or pharmacist

Useful questions include: What do you think is causing this? Is it likely to come back, and how can I prevent it? Which products should I stop? How long before I should expect improvement, and when should I come back if it isn't better? Are there side effects to watch for? Is this treatment safe if I am pregnant, breastfeeding or for my child? Writing your questions down, bringing your products (or photos of their labels) and taking dated photos of the problem make an appointment much more useful.