Mapping the 28-Day Cycle Before Choosing a Dosing Strategy
Tracking cycle days establishes when follicular and luteal phases occur.
- 28 days: Cycle length (typical average)
- Day 1–14: Follicular phase (pre-ovulation)
- Day 15–28: Luteal phase (post-ovulation)
- Luteal: PMDD symptom window (onset near ovulation)
Why cycle-day tracking matters
Symptom logs and ovulation markers define the luteal window for dosing.
Continuous Daily SSRI Dosing Across the Full Cycle
Daily dosing keeps blood levels steady across every cycle day.
- 28 / 28: Dosing days (every day of cycle)
- Steady: Blood level (minimal fluctuation)
- Higher: Adherence burden (daily pill habit)
- Depression Rx: Standard approach (legacy SSRI model)
Continuous strategy rationale
Steady-state dosing mirrors standard antidepressant treatment protocols.
Intermittent Luteal-Phase-Only SSRI Dosing
Dosing starts at ovulation and stops at menses, covering 14 days.
- 14 / 28: Dosing days (luteal phase only)
- 1–2 days: Onset speed (fast for PMDD)
- 14: Drug-free days (follicular phase)
- 1990s: First described (PMDD trials)
Luteal-only strategy rationale
PMDD symptoms track ovulation, so dosing only that window suffices.
Rapid Symptom Response: PMDD vs Classic Depression Timelines
PMDD relief begins within days, unlike weeks needed for depression.
- 24–48h: PMDD onset (much faster response)
- 2–4 wks: Depression onset (classic SSRI timeline)
- Short: Luteal restart lag (symptom relief resumes fast)
- Unclear: Mechanism (non-monoamine pathways proposed)
Why PMDD responds faster
Allopregnanolone modulation may explain the rapid symptom relief.
Comparing Cumulative Side Effect Burden Between Strategies
Half the exposure days generally means a lighter side effect load.
- 14 vs 28: Exposure days (luteal vs continuous)
- Lower: Sexual side effects (with luteal-only dosing)
- Cyclical: Discontinuation symptoms (monthly taper effect)
- Comparable: Efficacy parity (per trial evidence)
Trade-offs between the two strategies
Less drug exposure can lower burden without sacrificing much control.
Placeholder: overall control stays comparable across both strategies.