Table 1

Study schedule

Study periods	Screening phase			Intervention phase
Study periods	Preliminary screening of eligibility	Prospective PMS screening	L1 OA	Personal meeting (t0)	L2 OA	Midpoint study contact	L3 OA	Post-treatment study contact & OA (t2)
Visit/contact	Phone/post/online	At home (diary form)	Online	At study site	Online	At study site or phone/Skype	Online	Phone +post-treatment online
Day of menstrual cycle (MC)	−31–−1 day of 1. MC	1. day of 1. MC until end of 1. MC	−5–−1 of 2. MC	1–14 day of 2. MC	−5–−1 of 3. MC	1–14 day of 3. MC	−5–−1 of 4. MC	1–14 day of 4. MC
Menstrual phase	At any point	One whole MC	Luteal	Follicular	Luteal	Follicular	Luteal	Follicular
Time (min)	20	2 daily for 1 MC	10	60	10	15	10	30
Study information/informed consent	x
Inclusion/exclusion criteria	x	x		x
Randomisation				x
Placebo dragée intake in intervention arms				x	x	x	x
Narrative for OLP+ group				x		x
Primary outcome
PMS symptom diary		x	x	x	x	x	x
Safety variables			x	x	x		x	x
Suicidality assessment	x			x		x		x
Side-effects assessment						x		x

L, luteal phase; OA, online assessment; OLP, open-label placebo; PMS, premenstrual syndrome.