Understanding the Yuzpe Method and Its Hormonal Impact
The Yuzpe method is a form of emergency contraception (EC) that uses a combination of estrogen (ethinyl estradiol) and progestin (levonorgestrel) to prevent pregnancy after unprotected intercourse [1.6.3, 1.7.7]. This method involves taking two high-dose doses of specific combined oral contraceptive pills, 12 hours apart, within 72 hours of the event [1.6.5]. Its primary mechanism is to inhibit or delay ovulation, though it may also alter the endometrium to prevent implantation [1.6.1, 1.6.2, 1.6.4].
The Pharmacology of Sleepiness: Why Fatigue is a Side Effect
The core reason for feeling sleepy after using the Yuzpe method is the significant dose of hormones introduced into your system, particularly the progestin component. Fatigue is a known side effect of both combined hormonal contraceptives and progestin-only emergency contraception [1.2.6, 1.2.7].
High doses of progestins and estrogens, referred to as creating a 'pseudopregnancy' state, mimic the high hormone levels seen during pregnancy [1.3.2]. These hormonal fluctuations can directly impact energy levels. Progesterone and its synthetic forms (progestins) are known to have a sedative effect on the central nervous system. This is why women may experience tiredness during certain phases of their menstrual cycle or during pregnancy. The large, sudden dose in the Yuzpe regimen amplifies this effect, leading to noticeable sleepiness, drowsiness, or fatigue [1.2.3, 1.2.5]. In one study, fatigue was reported by 29% of women using the Yuzpe regimen [1.2.1].
Other Common Side Effects
Besides fatigue, the Yuzpe method is associated with a higher incidence of other side effects compared to newer, progestin-only EC methods [1.5.7]. These include:
- Nausea and Vomiting: This is the most common side effect, with some studies reporting nausea in up to 50% of users and vomiting in around 19% [1.4.1]. The high estrogen dose is a primary contributor to this [1.7.4].
- Headache and Dizziness [1.2.5]
- Breast Tenderness [1.2.4]
- Irregular Bleeding or Spotting [1.2.4]
- Abdominal Pain or Cramping [1.2.6]
These side effects are typically mild and resolve on their own within a day or two after completing the doses [1.2.4, 1.4.6].
Comparison of Emergency Contraception Methods
The Yuzpe method is now considered less effective and has more side effects than other available EC options [1.7.4, 1.7.5].
| Feature | Yuzpe Method | Levonorgestrel (e.g., Plan B) | Ulipristal Acetate (e.g., Ella) | Copper IUD |
|---|---|---|---|---|
| Hormone(s) | Estrogen & Progestin [1.6.3] | Progestin-only (Levonorgestrel) [1.7.3] | Selective Progesterone Receptor Modulator [1.7.3] | None [1.7.2] |
| Effectiveness | 56% to 89% [1.7.5] | Up to 85% [1.5.7] | More effective than Levonorgestrel [1.7.4] | Over 99% [1.7.3] |
| Common Side Effects | High rates of nausea, vomiting, fatigue [1.5.7] | Less nausea/vomiting than Yuzpe; fatigue, headache [1.5.7, 1.2.8] | Headache, nausea, abdominal pain, delayed menses [1.5.4, 1.7.7] | Pain on insertion, cramping, heavier periods [1.7.7] |
| Availability | Requires specific oral contraceptives [1.7.3] | Over-the-counter [1.7.4] | Prescription only [1.7.3] | Clinician insertion required [1.7.3] |
Managing Side Effects
If you experience sleepiness or other side effects from the Yuzpe method, here are some tips:
- Rest: Allow yourself to rest and take it easy for a day or two after the doses [1.4.3].
- Manage Nausea: Taking the pills with food can help reduce nausea. An anti-nausea medication (antiemetic) may be taken 30 minutes prior to the dose, but be aware that some antiemetics can also cause drowsiness [1.4.1, 1.4.2].
- Stay Hydrated: Drink plenty of fluids.
- Vomiting: If you vomit within two hours of taking a dose, you should contact your healthcare provider, as you may need to repeat it [1.4.6].
Conclusion
The pronounced sleepiness experienced after the Yuzpe method is a direct pharmacological consequence of the high dose of hormones, particularly progestin, which has a sedative effect. While effective to a degree, the Yuzpe regimen has a higher rate of side effects, including fatigue, compared to more modern alternatives like levonorgestrel-only pills or ulipristal acetate. The copper IUD remains the most effective form of emergency contraception [1.7.4]. If you have concerns about side effects, it is best to discuss EC options with a healthcare provider to determine the most suitable choice for you.
For more detailed information on emergency contraception options, you can visit the World Health Organization (WHO) fact sheet on Emergency Contraception [1.2.7].
