Can spironolactone affect menstrual cycles?

Spironolactone's Effect on Menstrual Cycles

Yes, spironolactone commonly causes menstrual irregularities in 15-30% of women, with this side effect being dose-dependent and one of the most frequently reported adverse effects of the medication. 1, 2

Mechanism and Frequency of Menstrual Changes

Spironolactone affects menstrual cycles through its anti-androgenic properties and hormonal effects:

• It works by decreasing testosterone production, inhibiting androgen receptors, and affecting hormone binding globulin 2
• Menstrual irregularities are the most common side effect, occurring in 15-30% of women taking the medication 2
• The risk increases significantly with higher doses, with a relative risk of 4.12 for women taking 200mg/day compared to lower doses 1
• Common menstrual changes include:
  • Metrorrhagia (irregular bleeding)
  • Shortened menstrual cycles (as short as 14-day cycles in some cases) 3
  • Polymenorrhea (frequent menstrual periods) 4

Dose-Related Effects

The likelihood of experiencing menstrual irregularities correlates strongly with the dosage:

• At 100mg twice daily (200mg total): Up to 68% of women may experience side effects severe enough to require dose reduction or discontinuation 3
• At 50mg twice daily (100mg total): Significantly fewer side effects, with only about 20% experiencing menstrual irregularities 3
• The American Academy of Dermatology recommends starting at 50mg daily and increasing as needed, which helps minimize these side effects 2

Management of Menstrual Side Effects

To address menstrual irregularities while continuing spironolactone therapy:

• Concomitant use of combined oral contraceptives (COCs) is highly effective in regulating menstrual cycles while on spironolactone 2
• Hormonal intrauterine devices can also help minimize menstrual irregularities 1
• Cyclical administration (days 4-21 of the menstrual cycle) rather than continuous dosing may reduce the incidence of irregular bleeding 3
• Starting at a lower dose (50mg daily) and gradually increasing as needed and tolerated can minimize side effects 2

Timing and Duration of Effects

• Menstrual irregularities typically occur early in treatment 5
• Regular monitoring during the first 3 months of treatment is advised to assess for side effects 5
• These effects are generally not dangerous but can be bothersome enough that some women discontinue treatment 3

Other Common Side Effects

While menstrual irregularities are most common, other side effects include:

• Diuresis (29%)
• Breast tenderness (3-5%)
• Breast enlargement
• Dizziness (3-4%)
• Nausea (2-4%)
• Polyuria (1-2%)
• Fatigue (1-2%)
• Headache (2%) 1, 2

Important Considerations

• Spironolactone is pregnancy category C and should not be used during pregnancy due to potential feminization of male fetuses 1, 2
• Despite menstrual irregularities, spironolactone does not appear to act as a progestin or antiprogestin on the human endometrium 6
• The menstrual effects are reversible upon discontinuation of the medication
• In studies examining long-term use, no serious adverse effects were noted with treatment durations up to 8 years 2