Sores and scabs on the head are crusted areas, open lesions, or dried blood on the scalp. While often minor, they can signal an underlying health issue. Understanding their causes helps in identification.
Inflammatory Scalp Conditions
Chronic inflammatory conditions affect the scalp, leading to irritation and the development of sores and scabs. Seborrheic dermatitis is one common condition, causing itchy, flaky, and greasy patches. It can range from mild dandruff to severe scaly patches, often linked to an immune reaction to Malassezia yeast. Persistent flaking and itching can prompt scratching, leading to scabs and sores.
Psoriasis is an autoimmune disorder causing the immune system to attack healthy skin cells. This leads to rapid skin cell buildup, forming raised, discolored patches, often with silvery-white scales. Scalp psoriasis can result in a dry scalp that may crack and bleed, along with itching and a burning sensation. Scratching these inflamed areas can further injure the skin, contributing to scabs and temporary hair loss.
Eczema, including atopic dermatitis, commonly affects the scalp, presenting as dry, itchy, and inflamed skin. On lighter skin, it may appear red; on darker skin, areas might be lighter or darker. Severe cases can lead to crusty patches and weeping sores. Intense itching often results in scratching, which can worsen the condition and create openings for secondary infections.
Infections and Infestations
Sores and scabs on the scalp can also arise from infections or parasitic infestations. Bacterial infections like folliculitis inflame hair follicles, often due to bacteria. This appears as small red bumps or pus-filled blisters around hair follicles, which can be itchy, sore, and tender, sometimes breaking open and crusting. Impetigo, another bacterial infection, causes highly contagious red sores that burst and form a yellow-brown crust.
Fungal infections, such as tinea capitis (scalp ringworm), are caused by dermatophyte fungi. This infection presents as itchy, scaly, and bald patches where hair may break off, sometimes leaving “black dots” or “gray patches.” A severe inflammatory reaction called a kerion can develop, appearing as a painful, pus-filled swelling with thick, yellow crusting.
Viral infections, including herpes zoster (shingles), can also manifest on the scalp. Shingles is caused by the reactivation of the varicella-zoster virus, which also causes chickenpox. It produces small blisters that can turn yellow and form a crust on the scalp. These lesions can be painful.
Parasitic infestations are another source of scalp irritation and sores. Head lice are tiny insects that infest the scalp and feed on blood, causing intense itching. The constant scratching due to lice bites can lead to abrasions and scabs on the scalp. Scabies, caused by the microscopic mite Sarcoptes scabiei, primarily causes severe itching and a rash. While more common in skin folds, it can also impact the scalp, especially in infants or those with compromised immune systems.
External Factors and Injury
Direct external factors and physical injuries can also contribute to sores and scabs on the scalp. Persistent scratching, regardless of the underlying cause of the itch, is a common culprit. Scratching can break the skin, leading to minor cuts, abrasions, and subsequent scab formation as the skin heals.
Minor cuts or abrasions resulting from accidental bumps, falls, or even vigorous hair brushing can directly cause scabs to form on the scalp. The skin’s natural healing process involves forming a scab to protect the wound and prevent further entry of germs.
Chemical irritations are another frequent cause, often stemming from reactions to hair care products. Hair dyes, bleaches, relaxers, or even harsh shampoos can contain chemicals that irritate the scalp, leading to symptoms like burning, itching, redness, dryness, and in severe cases, chemical burns. Such irritation can prompt scratching or direct skin damage, resulting in sores and scabs.
Overexposure to the sun’s ultraviolet (UV) rays can cause a sunburned scalp, which presents with pain, redness, tenderness, and sometimes blistering. As the skin heals, it may dry out and peel, sometimes resembling dandruff. A severe sunburn can damage hair follicles and potentially lead to temporary hair loss.
Certain hair accessories can also cause irritation or injury to the scalp. Tight hair ties, clips, or headbands can exert excessive pressure or cause friction against the scalp and hair shafts. This continuous pressure or rubbing can lead to hair breakage, pulling, and direct skin irritation or damage, contributing to scalp discomfort and the formation of small sores.