Home / Trigger atlas
The trigger atlas
Each page answers one question: if this happened, when does shedding typically start, peak and stop?
GLP-1 medications
Hair loss is listed in the Wegovy (semaglutide 2.4 mg) prescribing information in about 3% of adults versus 1% on placebo…
Life eventsPostpartum
Postpartum shedding is commonly noticed about two months after giving birth…
ProceduresAfter surgery & anaesthesia
Hair shedding after an operation is usually telogen effluvium…
Starting/stopping treatmentsStarting minoxidil
A temporary increase in shedding is commonly reported in the first weeks of minoxidil — the so-called 'dread shed' — and in one 2025 study of topical minoxidil it peaked around week 4 and was below baseline by week 16.…
Starting/stopping treatmentsStopping finasteride
According to the Propecia (finasteride 1 mg) FDA label…
MedicationsMounjaro & Zepbound (tirzepatide)
The Zepbound label lists hair loss in 4–5% of patients versus 1% on placebo…
ProceduresGastric sleeve & bariatric surgery
In a study of 156 women after sleeve gastrectomy…
Life eventsStopping breastfeeding
HealthLink BC notes that…
Life eventsStopping birth control
When a woman stops oral contraceptives…
Life eventsCOVID-19 & high fever
After COVID-19…
Life eventsCrash diet & fasting
Losing 20 pounds or more is a common trigger of excessive shedding (AAD)…
Starting/stopping treatmentsStopping minoxidil
If minoxidil is stopped…
ProceduresHair transplant shock loss
Shock loss (recipient-site effluvium) — shedding of native hairs around the grafts — typically occurs 2–8 weeks after surgery…
MedicationsLamotrigine (Lamictal)
In a review of pharmacovigilance reports of lamotrigine-associated alopecia…
MedicationsValproate (Depakote)
DermNet lists valproic acid as causing hair loss in 12–28% of users…
MedicationsIsotretinoin (Accutane)
A systematic review of 22 studies found hair loss in 3.2% of acne patients on isotretinoin below 0.5 mg/kg/day versus 5.7% on 0.5 mg/kg/day or more…
MedicationsSertraline & SSRIs
Hair loss is a rare reported side effect of sertraline…
MedicationsAnticoagulants (Eliquis, Xarelto, warfarin)
DermNet lists heparin and warfarin among drugs that cause telogen effluvium and says newer anticoagulants such as rivaroxaban…
MedicationsLevothyroxine changes
Levothyroxine labelling says partial hair loss may occur rarely during the first few months of therapy and is usually temporary.…
Labs & explainersFerritin & iron
One study of 155 women with hair loss defined iron deficiency as ferritin below 60 ng/mL and cited 40–60 ng/mL as the adequate level for hair growth — much higher than the level linked to anaemia — but thresholds differ…
Labs & explainersVitamin D
A case-control study of women with female pattern hair loss classed vitamin D below 20 ng/mL as deficient and 20–30 as insufficient…
Life eventsSeasonal shedding
In a UK study of 14 men…
Life eventsBraids & traction
Traction alopecia can get better when it has only been present for a few weeks or months if the tension is stopped…
Hair signsTelogen club hair
A shed hair with a small white bulb at the root is a resting (telogen) 'club' hair…
Hair signsRegrowth vs breakage
A fine fringe of short new hairs along the hairline is a common sign of recovery after telogen effluvium (DermNet)…