Telogen effluvium (TE) always starts 2-4 months after the triggering event, not when you first notice shedding. This delay makes trigger identification difficult from memory alone, because by the time hair starts falling out, the cause is already weeks or months in the past. Event logging combined with density tracking solves this by creating a searchable timeline that connects density changes to documented life events.
How the TE Lag Works
Hair follicles respond to physiological stress by prematurely entering the telogen (resting) phase. The hair in that follicle stops growing but does not fall out immediately. It takes 2-4 months for the telogen hair to release from the follicle and shed.
This means the timeline of TE follows a predictable pattern:
| Timeline | What Happens |
|---|---|
| Day 0 | Triggering event (illness, surgery, stress, etc.) |
| Days 1-14 | Affected follicles begin transitioning from anagen to catagen |
| Weeks 2-8 | Follicles enter telogen phase; hair stops growing |
| Months 2-4 | Telogen hairs release and shed; visible hair loss begins |
| Months 4-8 | Shedding peaks and gradually slows |
| Months 6-12 | New anagen hairs replace shed hairs; recovery visible |
Most people only start paying attention to their hair when shedding becomes noticeable at months 2-4. By that point, the actual trigger occurred weeks ago. Without a record of events from that earlier period, identifying the cause becomes guesswork.
Step 1: Start Logging Events Now
Do not wait until you experience shedding to start logging. The most valuable event logs are created before TE occurs, because they capture the trigger in real time rather than from memory.
Log these categories of events:
Health events. Any illness, fever, infection, surgery, dental procedure, or hospitalization. Include dates and severity.
Medication changes. Starting, stopping, or adjusting any medication. Include antidepressants, blood pressure medications, birth control, antibiotics, and supplements.
Nutritional changes. Crash diets, caloric restriction, elimination diets, or significant changes in protein intake. Low iron, zinc, and protein are documented TE triggers.
Hormonal events. Pregnancy, postpartum period, starting or stopping hormonal birth control, thyroid medication changes, or menopause-related treatment adjustments.
Stress events. Major emotional stressors: job loss, relationship changes, bereavement, relocation, financial stress. Rate the severity from 1 to 10.
Step 2: Take Regular Density Readings
Density readings every 2-4 weeks create the measurement baseline that makes trigger identification possible. When shedding begins, you can pinpoint exactly when density started declining by reviewing your reading history.
Without regular readings, you only know "shedding started sometime in October." With bi-weekly readings, you know "density in the frontal zone dropped 8% between October 4 and October 18." That precision narrows the trigger window from a vague memory to a specific 2-4 month lookback range.
Step 3: Count Backward From the Density Drop
When your density readings show a decline, look at your event log from 2-4 months before the first declining reading. Every logged event in that window is a potential trigger.
Example timeline:
| Date | Event / Reading |
|---|---|
| January 15 | Flu with 102F fever for 4 days (logged) |
| January 28 | Started new SSRI medication (logged) |
| February 10 | Density reading: stable |
| March 1 | Density reading: stable |
| March 20 | Density reading: 6% decline in frontal zone |
| April 5 | Density reading: 11% decline, shedding noticed |
Counting backward 2-4 months from the March 20 density drop points to the January 15-28 window. Two potential triggers exist: the flu and the new medication. Further analysis can narrow it down.
Step 4: Differentiate Multiple Triggers
When multiple events fall in the trigger window, consider these factors:
Severity and duration. A 4-day fever is a stronger physiological stressor than starting a low-dose medication. TE severity tends to correlate with trigger severity.
Known TE triggers. Some events are well-documented TE causes:
| Trigger Category | Common Examples | TE Likelihood |
|---|---|---|
| High fever / illness | Flu, COVID, pneumonia | High |
| Surgery | Any procedure requiring anesthesia | High |
| Crash diet | >800 calorie/day deficit | High |
| Postpartum | 2-4 months after delivery | Very high (affects 40-50%) |
| Iron deficiency | Ferritin below 40 ng/mL | High |
| Medication start/stop | SSRIs, retinoids, beta-blockers | Moderate |
| Emotional stress | Bereavement, divorce | Moderate |
| Thyroid dysfunction | Hypothyroidism onset | High |
Temporal precision. If shedding started exactly 3 months after one event and 2 weeks after another, the 3-month lag matches TE biology perfectly while the 2-week event is too recent to be the cause.
Step 5: Track Recovery After Trigger Removal
Once you identify the trigger, tracking becomes even more important during recovery. TE is self-resolving once the trigger is removed, but recovery takes 6-12 months.
Track density monthly during recovery to document:
- When shedding stops (density readings stabilize)
- When regrowth begins (density readings start increasing)
- How long full recovery takes
- Whether density returns to pre-TE baseline levels
If density does not begin recovering 3-4 months after trigger removal, the condition may be chronic TE or may overlap with androgenetic alopecia. Your tracking data gives a dermatologist the evidence to differentiate between these diagnoses.
When to Involve a Dermatologist
Your tracking data tells you when professional evaluation is needed:
- Shedding continues beyond 6 months with no density stabilization
- Density loss exceeds 25% in any zone
- No identifiable trigger exists in the 2-4 month lookback window
- Recovery stalls after trigger removal
- A pattern emerges (frontal or temporal-dominant loss) suggesting androgenetic alopecia overlap
Bring your complete event log and density timeline to the appointment. This data replaces the typical "when did it start?" guesswork with documented, date-stamped evidence.
Start Your Event Log Today
The best time to start logging events is before TE occurs. Every event you record now becomes a searchable data point if shedding starts months later.
Begin your density baseline and event logging at myhairline.ai/analyze. The tool is free and runs in your browser. For more on TE recovery patterns, see telogen effluvium recovery and stress-related hair loss tracking.
Medical disclaimer: Telogen effluvium can be caused by underlying medical conditions including thyroid disorders, iron deficiency, and autoimmune diseases. This article provides tracking guidance, not medical diagnosis. Consult a dermatologist if you experience significant or prolonged hair shedding. myhairline.ai is a tracking tool and does not diagnose or treat medical conditions.