Randomised trial, 1997
Does fluoxetine change menstrual cycle length in women with premenstrual dysphoria?
Yes, fluoxetine, especially at 60 mg per day, can change menstrual cycle length by 4 or more days, occurring in 15% of the 60 mg group versus 3% of the placebo group.
What they did
A two-phase study: first a 2-cycle single-blind placebo phase, then a 6-cycle double-blind phase. Only women who didn't respond to placebo were randomized to placebo, fluoxetine 20 mg daily, or fluoxetine 60 mg daily. Cycle length was tracked daily using prospective calendars.
What they found
At the end of the first treatment cycle, 11 of 62 women on 60 mg fluoxetine and 7 of 70 women on 20 mg fluoxetine, but only 1 of 61 women on placebo, showed cycle-length change of 4 or more days (P = .011). Over two or three treatment cycles, 15% of the 60 mg group, 6% of the 20 mg group, and 3% of the placebo group showed cycle changes (P = .048). Changes were either cycle shortening or lengthening equally.
What it means for you
Fluoxetine can affect menstrual cycle length in some women, particularly at higher doses, which is important for women of reproductive age taking antidepressants. The study only included women who didn't respond to placebo first.
11 of 62
Women on 60 mg with cycle change by end of first cycle
15%
Women on 60 mg with cycle change over multiple cycles
3%
Women on placebo with cycle change
About the study
- Original title
- Effect of fluoxetine on menstrual cycle length in women with premenstrual dysphoria
- Authors
- Steiner M, Lamont J, Steinberg S et al.
- Journal
- Obstetrics and gynecology
- Year
- 1997
- Study design
- Randomised trial
- Participants
- 70
- What was tested
- Fluoxetine 20 mg or 60 mg daily
- Read the paper
- doi.org/10.1016/s0029-7844(97)00307-4
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