May 2026 · 3 min read
Three conditions cause similar-looking nail changes. Here is how to tell them apart and what to do about each.
Appearance: Yellow, brown, or white discolouration starting at the tip or side of the nail. The nail thickens (you can feel it is thicker than normal). Debris collects under the free edge (a white or tan powdery substance). A musty smell is present when the nail is filed. The infection spreads slowly — weeks to months to involve the whole nail. Causes: Dermatophyte fungi (most common), yeast, or mould. Warm, moist environments (public showers, sweaty shoes, shared nail salon tools). Who gets it: Older adults (60% of people over 70 have some form of nail fungus). People with diabetes, poor circulation, or immune suppression. People who wear closed-toe shoes for long periods. Treatment: Antifungal medication (prescription — oral terbinafine is most effective, 12-week course, 80% cure rate. Topical antifungal alone has a 15-30% cure rate — it does not penetrate the nail plate well). Laser treatment ($500-1,000 per session, 60-70% cure rate, insurance usually does not cover it). Do not apply nail polish over fungus — it traps moisture and accelerates the infection.
Appearance: Pitting (small depressions in the nail plate, like the surface of a thimble). Onycholysis (the nail lifts from the nail bed, starting at the tip, leaving a white or yellow gap). Salmon-coloured spots under the nail (oil drop spots). The nail may crumble at the free edge. Causes: An autoimmune condition (the same immune overactivity that causes skin psoriasis also attacks the nail matrix). 80-90% of people with skin psoriasis have nail involvement at some point. 5-10% of people have nail psoriasis without skin involvement. Treatment: Corticosteroid ointment applied to the nail bed (prescription, 6-12 months for visible improvement). Vitamin D analogue ointment (calcipotriol, similar timeline). UV therapy for severe cases. Nail psoriasis can not be cured but can be managed. Jeannie Nails can apply polish over psoriasis (it does not make it worse — unlike fungus, where polishing is dangerous).
Appearance: A dark purple or black spot under the nail, usually at the point of impact (dropped something on the toe, slammed a finger in a door). The colour is uniform (not streaky like fungus). It grows out with the nail — a mark near the cuticle takes 4-6 months to reach the free edge. The nail may be tender for 2-3 days after injury. Causes: Trauma (dropped objects, crush injuries, sports impact). Tight shoes (repetitive pressure on the big toe causes subungual haematomas in runners). Treatment: None needed — it grows out on its own. If the pain is severe (the blood is under pressure): a doctor can drain it by making a small hole in the nail (trephination — a 5-minute procedure, immediate pain relief). Do not try to drain it yourself (sterile conditions are required — nail salon tools are not sterile enough for a medical procedure).
See a doctor if: the nail is painful beyond 3 days after injury, the discolouration does not grow out after 6 months (it should move toward the free edge — if it stays in the same spot it is not an injury), you have diabetes and any nail changes (diabetics have poor circulation in the feet — a fungal infection that looks minor can become a serious infection requiring amputation if left untreated).
At Jeannie Nails, our technicians can identify visible signs of fungus or psoriasis and recommend the right next step. Free identification with any service.
Free nail health check at Jeannie Nails.
