Bumps on scalp — acne, folliculitis, or seborrheic dermatitis?

The three conditions, distinguished

Scalp acne (acne capitis)

Same biology as facial acne — clogged follicles + bacteria + inflammation — appearing on the scalp instead of the face. Common in oily-scalp types and triggered by heavy hair products, hat-wearing, or hormonal patterns.

• Look: typical acne lesions — whiteheads, papules, occasionally pustules. May have black/whitehead centers visible.
• Distribution: anywhere with active sebaceous glands — typically along the hairline, at the crown, or behind the ears.
• Itch: low to moderate. Pain when pressed.
• Treatment: salicylic acid shampoo (used as a leave-on for 5-10 minutes), benzoyl peroxide wash, oral isotretinoin for severe cases. Standard acne treatment translated to the scalp.

Folliculitis (bacterial, fungal, or eosinophilic)

Inflammation of the hair follicle itself, usually from infection (Staphylococcus aureus is the most common bacterial cause; Malassezia for fungal "Pityrosporum folliculitis"). Distinct from acne because it\'s a true infection, not just a clog.

• Look: red bumps centered on hair follicles, often with a small white pustule. Sometimes itchy and tender. May spread in clusters.
• Distribution: often appears after sweating heavily (gym), wearing tight hats, shaving (the back of the neck), or after hot tub exposure (Pseudomonas folliculitis).
• Itch: usually moderate to severe, often the dominant symptom.
• Treatment: differs by cause. Bacterial: topical or oral antibiotics, antibacterial wash with chlorhexidine. Fungal: antifungal shampoo (ketoconazole 2%, selenium sulfide), oral antifungals for severe cases. Standard acne treatment (BP, salicylic) often worsens fungal folliculitis.

Seborrheic dermatitis (sebderm)

Chronic inflammatory condition driven by Malassezia yeast overgrowth + skin inflammation response. The same biology behind "dandruff" — sebderm is just the more severe form. Affects 1-3% of adults globally.

• Look: red patches with yellow/white greasy scaling. Sometimes "bumps" are actually clusters of scales. Distinct from acne — no individual pustule formation; the entire patch is inflamed.
• Distribution: scalp (especially crown and hairline), eyebrows, sides of nose, behind ears. The "T-zone of the head."
• Itch: often significant, especially when flaking is heavy.
• Treatment: antifungal shampoos (ketoconazole 2%, selenium sulfide 2.5%, zinc pyrithione 2%) used 2-3x weekly long-term. Topical steroids during acute flares (derm-prescribed). Tea tree shampoos help mild cases.

The mistakes that extend the problem

• Treating fungal folliculitis with benzoyl peroxide: BP doesn\'t kill Malassezia and the formulation can sometimes make fungal acne / folliculitis worse.
• Treating sebderm with hydrating shampoos: heavy moisturizing shampoos feed Malassezia overgrowth. Need anti-yeast actives, not "nourishing" products.
• Treating scalp acne with anti-dandruff shampoo only: ketoconazole doesn\'t address comedonal acne. Acne needs salicylic acid or BP.
• Picking or popping scalp lesions: scars permanently. Hair-follicle damage can cause permanent localized hair loss.
• Hot water + heavy scrubbing: strips the scalp barrier, worsens all three conditions.

The hair-products audit

Anything you put in your hair migrates onto your scalp and stays. The common culprits across all three conditions:

• Heavy conditioners and leave-in products with silicones — coat the follicle, trap sebum and bacteria.
• Dry shampoos used near the root daily — accumulate over time, especially aerosol-based formulas.
• Hair oils applied to the scalp (vs. mid-shaft and ends only) — feed Malassezia.
• Fragranced products — contact dermatitis trigger that worsens all three conditions.
• Pomades and styling waxes — heavy occlusion, common trigger for "pomade acne" on the hairline.

When to see a dermatologist or trichologist

• The protocol below doesn\'t improve symptoms in 4-6 weeks
• Hair shedding around the affected area (could be scarring alopecia developing)
• Painful or deep nodules under the scalp
• Spreading rapidly or to other body areas
• Discharge (yellow, foul-smelling) suggesting bacterial infection
• Eye or facial swelling alongside scalp symptoms