Understanding Desogestrel: What Is It?
Desogestrel is a synthetic, third-generation progestogen, a type of hormone used in oral contraceptives [1.2.2, 1.2.3]. As a prodrug, it is converted in the body into its active form, etonogestrel [1.2.4]. First discovered in 1972 and introduced in Europe in 1981, it is known for its potent progestogenic activity and minimal androgenic (male hormone-like) effects compared to older progestins [1.2.4, 1.4.4]. This high selectivity helps minimize side effects like acne and weight gain that were more common with earlier generations of progestins [1.2.3]. Desogestrel is widely used today in two main forms: as a standalone progestin-only pill (POP) and as a component in combined oral contraceptives (COCs) [1.2.4, 1.2.5].
The Direct Answer: The Role of Estrogen with Desogestrel
The answer to the question 'Is there estrogen in desogestrel?' depends on the specific product.
- Progestin-Only Pills (POPs): Formulations that contain only desogestrel, often called the 'mini-pill' (e.g., Cerazette, Cerelle), do not contain estrogen [1.2.5, 1.5.5]. These are specifically designed as an estrogen-free contraceptive option.
- Combined Oral Contraceptives (COCs): Desogestrel is also frequently paired with a synthetic estrogen called ethinyl estradiol in many birth control pills (e.g., Kariva, Apri, Desogen) [1.2.1, 1.2.6]. In the United States, desogestrel is only available in these combination forms [1.2.2].
So, while the desogestrel hormone itself is not estrogen, it is often administered alongside it in combination pills [1.2.1]. It's crucial to know which type of pill is being discussed.
How Desogestrel Works to Prevent Pregnancy
Desogestrel has a powerful multi-faceted mechanism of action. Its primary and most important effect is the consistent inhibition of ovulation—preventing the ovaries from releasing an egg [1.2.2, 1.3.4]. This makes it more effective than some older progestin-only pills that do not always stop ovulation [1.6.3].
Additionally, desogestrel works by:
- Thickening cervical mucus: This creates a barrier that makes it difficult for sperm to enter the uterus and reach an egg [1.4.2, 1.6.3].
- Thinning the uterine lining (endometrium): This change makes the lining less hospitable for a fertilized egg to implant and grow [1.4.2, 1.6.5].
This combination of actions makes desogestrel a highly effective contraceptive, with a failure rate as low as 0.14 per 100 woman-years in some studies [1.3.4].
Progestin-Only Pills vs. Combination Pills: A Comparison
Choosing between a desogestrel-only pill and a combination pill involves understanding their key differences.
| Feature | Desogestrel (Progestin-Only Pill) | Combination Pill (with Desogestrel) |
|---|---|---|
| Hormones | Desogestrel (a progestin) only [1.2.5] | Desogestrel (a progestin) and Ethinyl Estradiol (an estrogen) [1.2.1] |
| Primary Mechanism | Consistently inhibits ovulation and thickens cervical mucus [1.3.4] | Suppresses ovulation and alters cervical mucus/uterine lining [1.3.6] |
| Dosing Schedule | One active pill taken continuously every day at the same time [1.5.5] | Typically 21 active pills followed by a 7-day break or placebo pills [1.5.5] |
| Effect on Periods | May cause irregular bleeding, spotting, or lead to no periods at all (amenorrhea) [1.5.6] | Typically results in regular, predictable withdrawal bleeding during the placebo week [1.5.3] |
| Suitable For | Breastfeeding women; smokers over 35; those with a history of blood clots, migraines with aura, or high blood pressure [1.6.1, 1.6.2] | Women without specific contraindications to estrogen [1.9.2] |
Who is an Ideal Candidate for Desogestrel-Only Pills?
A progestin-only pill like desogestrel is a vital alternative for individuals who have contraindications to estrogen-containing contraceptives. Healthcare providers often recommend it for those who [1.6.2, 1.9.2, 1.9.5]:
- Are breastfeeding, as it does not affect milk production [1.6.6].
- Are over 35 and smoke.
- Have a history of venous thromboembolism (blood clots in the legs or lungs).
- Suffer from migraines with aura.
- Have uncontrolled high blood pressure (hypertension).
- Have a history of heart disease or stroke.
- Have certain types of lupus [1.6.3].
Potential Side Effects and Risks
Like all medications, desogestrel has potential side effects. The most common one is a change in menstrual bleeding patterns, which can include irregular bleeding, spotting, or amenorrhea (the absence of periods) [1.5.6]. Other common side effects may include headaches, nausea, breast tenderness, and mood changes [1.5.6]. While third-generation progestins like desogestrel are designed to have fewer androgenic effects, some people might still experience acne [1.2.3, 1.5.6].
A significant consideration is the risk of venous thromboembolism (VTE), or blood clots. While progestin-only pills are considered a safer option for those at risk [1.6.1], some studies suggest that combination pills containing desogestrel may have a slightly higher risk of blood clots compared to pills with second-generation progestins like levonorgestrel [1.2.3, 1.4.3].
Conclusion
To conclude, desogestrel itself is a progestin and contains no estrogen [1.2.2]. When prescribed as a progestin-only pill or 'mini-pill,' it is an entirely estrogen-free contraceptive [1.2.5]. However, it is also a key component in many combination birth control pills, which do contain the estrogen ethinyl estradiol [1.2.1]. The choice between a POP and a combination pill depends heavily on an individual's health profile, medical history, and tolerance for estrogen. Consulting with a healthcare provider is essential to determine the most appropriate and safest contraceptive method.
For more information on progestogen-only pills, you can visit the NHS page on the progestogen-only pill.
