Skin and Hair Safety: Irritation, Patch Tests, Infection, Changing Moles and Sudden Hair Loss

Get urgent help first

Some skin problems are emergencies. In the United States call 911 (use your local emergency number elsewhere). The NHS says to call emergency services if skin infection (cellulitis) comes with a very high temperature or feeling hot, cold or shivery, a fast heartbeat or fast breathing, purple patches on the skin, dizziness or fainting, confusion, or cold, clammy or pale skin. [1] Psoriasis with skin that quickly turns red with white pus-filled bumps that join together, or pus-filled yellow-brown patches on the feet, also needs emergency care. [2] Do not drive yourself if you feel very unwell. [1]

Same-day or urgent care

• Possible skin infection: painful, hot, swollen skin, usually red (redness can be harder to see on brown and black skin), possibly blistered, sometimes with flu-like symptoms. The NHS advises urgent medical advice because early antibiotics can stop it becoming more serious. [1]
• Eczema that looks infected: blistered, crusty, leaking fluid, pus-filled spots, painful, swollen or warm skin, sudden worsening, fever or feeling unwell. These can be signs of infection or eczema herpeticum. [3]
• Rosacea with eye symptoms: painful eye, blurred vision, light sensitivity, a red or gritty eye. These could be signs of keratitis. [4]
• Sunburn: the NHS says to seek medical help if you feel unwell or the skin swells badly. [5]

Changing moles and spots

Most moles are harmless, but see a GP for a mole that has changed size, shape or color; is painful or itchy; is inflamed, bleeding or crusty; or for a new or unusual mark that has not gone away after a few weeks. [6] Melanomas are often an uneven shape, may have two or more colors, tend to be larger than about 6 mm (but can be smaller), and can change over time. [7] The NHS also lists a dark area under a nail not caused by injury, and says melanomas are more common in sun-exposed areas, while rarer types can affect the eyes, soles, palms or genitals. [7] Finding melanoma early can make it easier to treat. [6] Do not treat a changing mole with home or natural products.

Sudden, patchy or scarring hair loss

See a clinician for sudden heavy shedding, round bald patches, or a sore, red or scaly scalp. Alopecia areata causes sudden round patches. [8] Scarring alopecias cause permanent hair loss. [9] The NHS advises seeing a GP before using a commercial hair clinic. [10] See Hair shedding and thinning and Alopecia areata and scarring hair loss.

Irritation and sensitization

Irritant reactions come from the skin being damaged by substances like soaps, detergents and shampoos. Allergic reactions come from an immune response, can first appear after years of use of a product, and last for life once established. [11] Fragrances, preservatives, hair dyes and some metals are common allergens. [11] Stop a product that burns, itches or causes a rash and talk to a pharmacist or clinician. The NHS notes emollients themselves can occasionally cause stinging, burning or folliculitis. [12] See Contact dermatitis.

Essential oils and "natural" products

Nearly 80 essential oils have caused contact allergy, mostly after pure or high-concentration use. [13] Read Essential oil safety, Natural ingredient safety and Natural does not mean safe.

Patch tests: what they can and cannot tell you

Clinical patch testing uses patches with specific allergens worn for 48 to 96 hours, kept dry, then read by a provider. [14] It needs at least 3 visits and a skilled interpreter, and is for people with long-term or repeated contact dermatitis. [11] There is no test for irritant contact dermatitis. [14] Proper evidence not found for a validated at-home patch test in the sources I checked, so a small dab of product on the forearm cannot guarantee safety.

Supplements and lab tests

High-dose biotin can falsely raise or lower some blood test results, including thyroid tests. [15] Tell your clinician and the lab about any supplements before blood work. Read medication interactions and Collagen, biotin and beauty supplements.

Pregnancy, children and sun

The FDA says sunscreen is not recommended for infants under six months and to ask a doctor first. [16] Itchy skin during pregnancy should be checked with a GP or midwife because it can sometimes be caused by a liver condition. [17] See Pregnancy and breastfeeding safety.