What is the typical timeframe for the onset of hair loss after a Covid-19 (Coronavirus disease 2019) infection?

Hair Loss After COVID-19 Infection: Onset Timeline

Hair loss typically begins approximately 2-3 months after COVID-19 infection, with studies showing an average onset of about 50-74 days after initial COVID-19 symptoms. 1, 2

Timing and Characteristics of Post-COVID Hair Loss

• Post-COVID hair loss most commonly presents as telogen effluvium (TE), a non-scarring diffuse hair loss that occurs following a stressful event such as infection 2
• The mean duration from COVID-19 symptom onset to the appearance of hair loss is approximately 74 days, which is earlier than classic acute telogen effluvium 2
• More specifically, one study found that hair shedding began on average 50 days after the first symptom of COVID-19 infection 1
• This timeline is consistent with the Nature Reviews Microbiology guideline which notes that hair loss is more common at 1 year than at 2 months after infection, indicating its delayed onset 3

Risk Factors and Associations

• Female gender is significantly associated with higher incidence of post-COVID hair loss (42.3% of women vs. 6.2% of men in one study) 4
• Patients with hypertension showed higher rates of COVID-induced telogen effluvium (40.4% vs. 23.1% in those without hypertension) 4
• Respiratory symptoms during COVID-19 infection are associated with higher rates of subsequent hair loss (31.7% vs. 14.0% in those without respiratory symptoms) 4
• High temperature during COVID-19 infection is significantly associated with subsequent hair loss 5
• Prior history of hair loss before COVID-19 infection increases the risk of developing post-COVID hair loss 5

Prevalence and Clinical Course

• Studies show that approximately 27.9-36.7% of COVID-19 patients develop telogen effluvium after infection 4, 5
• One large survey found that 52.7% of participants reported experiencing hair loss after COVID-19 infection 5
• The severity of COVID-19 appears to correlate with the likelihood of developing hair loss, with hospitalized patients showing higher rates than outpatients (31.7% vs. 24.3%) 4
• Most patients recover from post-COVID hair loss as it is typically self-limiting, though the timeline for recovery varies 2

Pathophysiology and Mechanisms

• Post-COVID hair loss is believed to be primarily due to acute telogen effluvium, though other mechanisms may contribute including anagen effluvium, androgenetic alopecia, and alopecia areata 6
• The physiological and psychological stress of COVID-19 infection likely triggers the hair follicles to prematurely enter the telogen (resting) phase 1
• Medications used to treat COVID-19 (antibiotics, systemic corticosteroids, hydroxychloroquine) may also contribute to hair loss in some patients 1
• The systemic inflammatory response during COVID-19 infection may disrupt normal hair cycle regulation 6

Clinical Implications and Management

• Clinicians should consider a history of recent SARS-CoV-2 infection in patients presenting with diffuse hair loss 4
• Trichoscopic findings typically include decreased hair density, empty follicles, and short regrowing hair 2
• While most cases resolve spontaneously, topical minoxidil may provide relief from post-COVID hair loss, though more research is needed to confirm its efficacy 6
• Hair loss after COVID-19 can significantly impact quality of life, with 8.6% of affected individuals reporting severe life impact according to the Dermatology Life Quality Index 5

Understanding the timeline and characteristics of post-COVID hair loss can help clinicians provide appropriate counseling and reassurance to affected patients, reducing unnecessary anxiety about this typically self-limiting condition.