Folliculitis decalvans (FD) is officially classified as a rare scalp disorder. It accounts for roughly 6% of alopecia cases seen in public dermatology clinics and about 1% in private practice settings, making it uncommon even among people already seeking help for hair loss. Exact population-wide prevalence numbers haven’t been established, but the condition is rare enough that many general practitioners may never encounter a case.
How It Compares to Other Hair Loss Conditions
FD belongs to a group called primary cicatricial alopecias, conditions where inflammation destroys hair follicles and leaves permanent scarring. Within that already-small category, FD is one of the more frequently diagnosed subtypes, but the entire category is uncommon. To put it in perspective, the vast majority of people with hair loss have nonscarring forms like androgenetic alopecia (typical male- or female-pattern hair loss), which affects roughly half of all adults. Scarring alopecias as a whole represent a small fraction of dermatology visits, and FD is a slice of that fraction.
Who Gets It
FD affects men about three times more often than women, with a male-to-female ratio of approximately 3.3 to 1. The average age at diagnosis is around 38, though it can appear earlier or later. Most reported cases involve people with lighter to medium skin tones (Fitzpatrick skin types I through IV), though this may partly reflect which populations have been studied rather than a true biological limit. The condition has been documented across ethnic groups worldwide.
What FD Looks Like
The hallmark feature is hair tufting: multiple strands of hair, sometimes five or more, emerging from a single follicle opening, resembling the bristles of a toothbrush. This happens because neighboring follicles are destroyed by inflammation and the remaining ones get bundled together under scar tissue. Over time, those tufts fall out too, leaving smooth, shiny bald patches with no follicle openings visible.
Dermatologists examining the scalp with magnification typically find three key signs: tufted hairs (present in roughly 86 to 95% of cases), redness around the follicle openings, and thickened scales at the base of hairs. Pustules on the scalp are also common and tend to signal more severe disease with a worse outlook. Many patients also report itching, scalp tenderness, or both.
What Causes It
The exact cause remains unknown, but the bacterium Staphylococcus aureus plays a central role. Rather than a straightforward skin infection, FD appears to involve an abnormal immune response to this common bacterium. S. aureus has been found not just in active pustules but also in apparently normal-looking skin and deeper tissue layers in FD patients, which helps explain why the condition keeps coming back.
Bacterial biofilms, sticky colonies of bacteria that are difficult for antibiotics to penetrate, likely contribute to the problem. When antibiotic treatment clears S. aureus from the scalp, symptoms improve. But because the bacteria are embedded so deeply and protected by biofilms, complete eradication is difficult, and symptoms typically return once treatment stops.
Treatment and Relapse Rates
The standard approach involves long courses of oral antibiotics, often a combination that targets S. aureus from multiple angles. Other options include vitamin A derivatives and anti-inflammatory medications. None of these are curative. Current treatments are generally described as suboptimal, working well while you take them but losing their effect afterward.
Relapse rates are high. Patients who receive less than three months of combined antibiotic therapy relapse about 66% of the time. Even with one of the more promising oral medications (isotretinoin), over half of patients relapse within two to three months of stopping. This cycle of treatment, improvement, and flare is one of the most frustrating aspects of living with FD and a major reason some patients eventually explore surgical options for severely affected areas.
Living With a Rare Condition
Studies measuring quality of life in FD patients find a mild to moderate negative impact overall, with emotional well-being taking the biggest hit. About 10% of patients experience a serious reduction in quality of life. The emotional toll tends to scale with disease severity: larger areas of scarring correlate with stronger feelings of distress and a greater sense that the condition controls daily life.
One revealing finding from patient surveys is that nearly half of people with FD believe their condition worsened because of inadequate medical care earlier on. This perception likely reflects the reality of having a rare disease. Many patients see multiple doctors before getting a correct diagnosis, and even once diagnosed, the lack of a reliable cure can feel like neglect. Nearly half also attribute flares to stress, which aligns with the general understanding that immune-mediated conditions can worsen under psychological pressure.
Because FD is rare, finding a dermatologist experienced with cicatricial alopecias can make a significant difference. Specialty hair loss clinics and academic medical centers are more likely to have providers who have managed multiple FD cases and can offer the most current treatment strategies, including monitoring for antibiotic resistance, which is an increasing concern with repeated courses of therapy.