What causes decreased libido after starting oral contraceptive pills (OCPs)?

Causes of Decreased Libido After Starting Oral Contraceptive Pills

The primary cause of decreased libido after starting oral contraceptive pills is the hormonal effect of the estrogen component, which reduces free testosterone levels by increasing sex hormone binding globulin (SHBG) production, leading to less bioavailable testosterone for maintaining normal sexual desire. 1, 2

Hormonal Mechanisms

• The estrogen component (typically ethinyl estradiol) in combined oral contraceptives increases production of sex hormone binding globulin (SHBG), which binds to circulating testosterone, reducing free testosterone levels available for maintaining normal sexual desire 3

• Synthetic progestins in OCPs may have varying effects on androgen receptors, potentially enhancing the libido-reducing effects of estrogen through off-target effects on both androgen and estrogen receptors 4

• The specific formulation matters - studies show that pills containing very low doses of ethinyl estradiol (15 μg) are more likely to decrease libido compared to those containing 20-35 μg 3

Prevalence and Patterns

• Research indicates approximately 15% of women report decreased libido while using combined oral contraceptives, while 85% report either increased libido or no change 3

• The effects on libido are not universal - individual responses vary significantly based on hormonal sensitivity, prior sexual function, and psychological factors 2

• Depression, which can independently affect libido, has been reported as a side effect in some women using OCPs, creating a potential compounding effect on sexual desire 5

Physical Changes Contributing to Decreased Libido

• OCPs can cause physical changes that may contribute to sexual discomfort and subsequently reduced desire:
  • Decreased thickness of labia minora and reduced vaginal introitus area 1
  • Increased pulsatility index of clitoral and labial arteries, potentially reducing blood flow to genital tissues 1
  • Increased reports of pain during intercourse (dyspareunia) in some women 1

Newer Formulations and Their Effects

• Newer progestins like drospirenone have different side effect profiles but can still affect sexual function - one study found that an OCP containing 30 μg ethinyl estradiol and 3 mg drospirenone was associated with:

  • Decreased frequency of sexual intercourse
  • Reduced spontaneous arousability
  • Diminished frequency of orgasm during intercourse 1

• Natural estrogens (estradiol valerate and estetrol) in newer OCPs may have fewer side effects overall, but their specific impact on libido is not well established 4

Progestin-Only Options

• Progestin-only pills (POPs) are not associated with the same degree of SHBG elevation and may have less impact on libido than combined oral contraceptives 4

• Women experiencing decreased libido on combined OCPs might benefit from switching to progestin-only methods 4

Clinical Considerations

• Healthcare providers should counsel patients about potential sexual side effects before starting OCPs, as decreased libido is a common reason for discontinuation 5

• For women experiencing decreased libido on OCPs, consider:

  • Switching to a different OCP formulation with different estrogen/progestin balance
  • Trying progestin-only contraceptives
  • Using non-hormonal contraceptive methods if sexual side effects persist 2

• The relationship between OCPs and libido is complex and not well studied, making it important to individualize contraceptive choices based on a woman's overall health, contraceptive needs, and sexual function 2