Psoriasis under the nail bed: what to know

Nail psoriasis can involve the nail bed, nail plate or the tissue that makes the nail. Lifting creates a gap beneath the nail where debris may gather; thickening, ridges, crumbling or colour change can also occur. Nail fungus and repeated injury may look similar, and both conditions can occur together, so appearance alone cannot confirm the cause. Nail changes are more suggestive of psoriasis when skin plaques, scalp symptoms or joint complaints are present, but an examination remains useful.

Keep nails trimmed, dry and clean without digging underneath them. Wear gloves for prolonged contact with water or cleaning products, and avoid biting, picking, aggressive manicures and artificial nails while the nail is fragile. Protect fingertips from knocks and moisturise the surrounding skin. A clinician may recommend a nail-applied medicine or treatment for associated skin disease; use it consistently and allow time for new nail growth to show change.

Arrange an appointment for a new, persistent or worsening nail change, especially if several nails are involved. Seek prompt care for increasing pain, warmth, swelling, pus, a dark streak that changes, or a nail that separates after an injury. Report finger or toe stiffness, swelling or tenderness because these symptoms may need assessment alongside the nail.

Ask whether the change looks like nail psoriasis, fungus, injury or more than one condition. Ask whether testing is needed, how to apply treatment beneath or around the nail, and which signs suggest infection or joint involvement.