What are the pros and cons of the copper intrauterine device (IUD) versus the hormonal intrauterine device (IUD), such as Mirena (levonorgestrel), to help decide which one is right for a patient?

Copper vs. Hormonal IUD: Comparison for Patient Decision-Making

Both copper and hormonal IUDs are highly effective contraceptive options with failure rates less than 1%, but the hormonal IUD (LNG-IUD) offers additional benefits including reduced menstrual bleeding and management of menstrual symptoms that make it the preferred choice for most patients.

Effectiveness Comparison

• Both IUD types have >99% effectiveness with typical use 1
• Copper IUD (Cu-IUD): 0.8% typical failure rate 1
• Hormonal IUD (LNG-IUD): 0.1-0.2% typical failure rate 1, 2
• Five-year pregnancy rates: LNG-IUD 1.1% vs. Cu-IUD 1.4% (not statistically significant) 3

Duration of Use

• Copper IUD: Approved for 10 years, effective for up to 12 years 4
• Hormonal IUD: Duration varies by formulation
  • 13.5 mg LNG-IUD (Skyla): 3 years 4
  • 52 mg LNG-IUD (Mirena): Approved for 5 years, effective for up to 7 years 4
  • 52 mg LNG-IUD (Liletta): 3 years 4

Menstrual Effects

Copper IUD

• Regular menstrual cycles continue 4
• May cause heavier bleeding and increased cramping, especially in first few months 4
• Associated with decreased hemoglobin levels (average 0.2 g/dL decline) 2

Hormonal IUD

• Causes irregular bleeding initially, but overall bleeding decreases significantly 4
• Many women experience amenorrhea (absence of periods) over time 4, 5
• Increases hemoglobin levels (average 0.5 g/dL increase) 2
• Significantly reduces dysmenorrhea (painful periods) 5, 6
• Approximately 50% of users experience amenorrhea or oligomenorrhea by 2 years 1

Additional Benefits

Copper IUD

• Non-hormonal option for those who cannot or prefer not to use hormones 1
• Can be used as emergency contraception (most effective emergency contraceptive) 7
• No backup contraception needed when initiating 4

Hormonal IUD

• Treats heavy menstrual bleeding and dysmenorrhea 1, 6
• Provides endometrial protection 1
• Reduces incidence of myoma and myoma-related surgery compared to copper IUD 5
• Recently shown to be effective for emergency contraception (non-inferior to copper IUD) 7
• May help manage adenomyosis and endometrial hyperplasia 6

Side Effects and Complications

Copper IUD

• Higher rates of bleeding and pain-related removals 2, 3
• May worsen anemia in predisposed individuals 2

Hormonal IUD

• Higher rates of amenorrhea-related removals (10.7% vs 0.2% for copper IUD) 2
• May cause hormonal side effects such as headache, skin and hair conditions 5
• Delayed ovarian follicular atresia reported 5

Special Considerations

• Both IUDs are safe for nulliparous women (women who have never given birth) 4
• Both have low rates of pelvic infection (0.6-0.7 per 100 years of use) 5
• Adverse effects for both types are highest in the first 2 years and in women under 25 5
• When switching from copper to hormonal IUD, backup contraception for 7 days may be needed if >7 days after starting menses 4

Decision Algorithm

1. If the patient has heavy or painful periods: Hormonal IUD preferred
2. If the patient wants to avoid hormones: Copper IUD preferred
3. If the patient is anemic or at risk for anemia: Hormonal IUD preferred
4. If the patient wants the longest duration: Copper IUD preferred
5. If emergency contraception is the primary goal: Either is effective 7

Common Pitfalls to Avoid

• Don't assume all patients will tolerate the increased bleeding with copper IUD, especially those with existing heavy periods
• Don't overlook the therapeutic benefits of hormonal IUD for menstrual disorders
• Don't forget that both IUDs are safe for nulliparous women despite older misconceptions 4
• Remember that side effects for both types tend to decrease over time 5