What types of hair loss are caused by isotretinoin (13-cis-retinoic acid) intake?

Hair Loss Types Associated with Isotretinoin

Isotretinoin primarily causes telogen effluvium, a diffuse, non-scarring pattern of hair loss that is reversible upon drug discontinuation. 1, 2, 3

Primary Pattern: Telogen Effluvium

The predominant type of hair loss from isotretinoin is telogen effluvium, characterized by:

• Diffuse, non-scarring alopecia affecting the entire scalp 1
• Onset timing: Typically begins 1-3 months after medication initiation 1
• Reversibility: Hair loss resolves within 3-6 months after the body adjusts or the drug is discontinued, with regrowth occurring at approximately 1 cm per month 1
• Mechanism: Isotretinoin shifts hair follicles from anagen (growth phase) to telogen (resting phase), resulting in decreased total hair count, density, and proportion of anagen hairs 3

Incidence and Dose Relationship

The frequency of isotretinoin-induced hair loss appears dose-dependent:

• Lower doses (<0.5 mg/kg/day): Hair loss occurs in approximately 3.2% of acne patients 4
• Standard/higher doses (≥0.5 mg/kg/day): Hair loss frequency increases to 5.7% 4
• Comparative safety: Isotretinoin demonstrates "less hair loss" compared to acitretin, another retinoid that causes hair loss in up to 75% of patients 5, 1

Risk Factors for Hair Loss

Patients more likely to experience isotretinoin-induced alopecia include those with:

• Older age at treatment initiation 2
• Higher cumulative doses of isotretinoin 2
• Longer treatment duration 2

Rare Presentation: Alopecia Areata

While extremely uncommon, alopecia areata (localized patches of hair loss) has been reported as a potential side effect:

• One case report documented a 24-year-old female developing localized patch hair loss after 6 months of isotretinoin treatment 6
• The causal relationship remains uncertain, and this may represent coincidental occurrence rather than true drug effect 6
• The exact mechanism by which retinoids might trigger alopecia areata is unknown 6

Clinical Implications

Short-term use at standard doses (0.5-1.0 mg/kg/day) does not significantly alter hair growth parameters in most patients 7. However, physicians should:

• Counsel patients about the 3-2% to 5.7% risk of telogen effluvium prior to initiating therapy 4
• Consider lower daily dosing regimens when hair loss is a significant patient concern 4
• Reassure patients that hair loss is typically reversible and self-limited 1