Understanding Rigevidon: A Combined Oral Contraceptive
Rigevidon is a prescription-only combined oral contraceptive pill, often simply called 'the pill' [1.3.3, 1.3.5]. It contains two active ingredients that are synthetic versions of female sex hormones: 30 micrograms of ethinylestradiol (an oestrogen) and 150 micrograms of levonorgestrel (a progestogen) [1.3.1]. When taken correctly, it is a highly effective and reversible method of birth control, with a failure rate of approximately 1% per year [1.2.2]. However, it's important to note that like other similar pills, Rigevidon does not offer protection against sexually transmitted infections (STIs); only condoms can provide that protection [1.2.1].
The Three-Way Mechanism of Action
The primary way Rigevidon prevents pregnancy is by overriding the natural menstrual cycle through the consistent delivery of these hormones [1.3.5]. This creates a state in the body that is not conducive to conception. The question 'How does Rigevidon work?' can be answered by looking at its three distinct but complementary actions [1.2.1, 1.3.2, 1.2.6]:
- Inhibition of Ovulation: The primary mechanism is preventing the ovaries from releasing an egg each month [1.2.1]. The hormones in Rigevidon, particularly the progestin (levonorgestrel), provide negative feedback to the hypothalamus, which in turn reduces the secretion of Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH) from the pituitary gland [1.2.7]. Without the mid-cycle LH surge, an egg is not released from the follicle, making fertilization impossible [1.2.7].
- Thickening of Cervical Mucus: The hormones also cause the mucus at the cervix (the neck of the womb) to thicken [1.2.1]. This thickened mucus acts as a physical barrier, making it significantly more difficult for sperm to travel from the vagina into the uterus to reach an egg, should one be unexpectedly released [1.3.7].
- Alteration of the Uterine Lining: Finally, Rigevidon alters the endometrium, which is the lining of the womb [1.2.1]. It causes the lining to become thinner, making it less receptive and unlikely to accept a fertilised egg for implantation [1.2.6]. This provides an additional layer of protection against pregnancy.
The Role of Active Ingredients
- Ethinylestradiol (Oestrogen): This synthetic oestrogen helps to stabilize the endometrium, preventing irregular breakthrough bleeding [1.2.7]. It also works with the progestin to suppress FSH secretion, which helps prevent the development of an ovarian follicle [1.2.7].
- Levonorgestrel (Progestogen): This synthetic progestin is primarily responsible for the contraceptive effect [1.2.7]. It inhibits the LH surge needed for ovulation, thickens cervical mucus, and makes the uterine lining unsuitable for pregnancy [1.2.7, 1.3.5].
How to Take Rigevidon for Maximum Effectiveness
Rigevidon typically comes in a calendar pack of 21 tablets [1.3.1]. The standard method involves taking one tablet at the same time each day for 21 consecutive days [1.6.6]. This is followed by a 7-day tablet-free interval, during which a withdrawal bleed (similar to a period) usually occurs [1.6.6]. Protection from pregnancy continues during this 7-day break, provided the pills were taken correctly and the next pack is started on time [1.6.3].
Modern approaches, known as tailored regimes, are also possible under medical guidance [1.6.4]. These can include 'tricycling' (taking three packs back-to-back before a break) or continuous use to reduce the frequency of withdrawal bleeds [1.6.1]. If a pill is missed, contraceptive protection may be reduced. If a pill is less than 12 hours late, it should be taken as soon as remembered, and protection is not reduced [1.6.5]. If it is more than 12 hours late, the advice depends on where in the cycle the pill was missed, and additional contraception like condoms may be needed for the next 7 days [1.6.6].
Benefits Beyond Contraception
Besides preventing pregnancy, combined pills like Rigevidon can offer other health benefits. They are sometimes prescribed to help manage heavy or painful periods (dysmenorrhea), symptoms of Polycystic Ovary Syndrome (PCOS), and acne [1.3.3, 1.5.5]. Use of combined oral contraceptives is also associated with a reduced risk of ovarian and endometrial cancers [1.5.2, 1.5.3].
Potential Risks and Side Effects
Like all medicines, Rigevidon can cause side effects. Common side effects, which often settle down after the first few months, include mood changes, nausea, headaches, breast tenderness, and changes in weight [1.4.6, 1.5.4].
The most serious, though rare, risk associated with combined hormonal contraceptives is an increased risk of developing blood clots (venous thromboembolism or VTE) [1.4.6]. The risk is small, estimated to be about 5-7 in 10,000 women using a levonorgestrel-containing pill like Rigevidon for a year, compared to about 2 in 10,000 women not using one [1.4.8]. This risk is higher for individuals with certain risk factors, such as being very overweight (BMI > 30), smoking (especially if over 35), or having a personal or family history of blood clots [1.4.6, 1.3.2].
| Feature | Rigevidon | Progestogen-Only Pill (Mini-Pill) | Non-Hormonal (Copper IUD) |
|---|---|---|---|
| Hormones | Ethinylestradiol & Levonorgestrel [1.3.1] | Progestogen only (e.g., Desogestrel) [1.3.6] | None |
| Primary Action | Prevents ovulation [1.2.1] | Thickens cervical mucus [1.2.4] | Prevents fertilization (spermicidal) |
| User Schedule | 21 days on, 7 days off (standard) [1.6.6] | Taken every day with no break [1.6.1] | Inserted once, lasts 5-10 years |
| Typical Efficacy | ~95% with typical use [1.3.2] | ~95% with typical use | >99% effective |
| Effect on Periods | Can make periods lighter, more regular [1.3.3] | Can cause irregular bleeding or stop periods | Can make periods heavier and more painful |
| Blood Clot Risk | Small increased risk [1.4.6] | Not associated with increased risk | No hormonal risks |
Conclusion
Rigevidon works as an effective contraceptive through a powerful, multi-faceted mechanism driven by its two hormonal components, ethinylestradiol and levonorgestrel. By consistently preventing ovulation, thickening cervical mucus, and thinning the uterine lining, it creates a robust defense against unwanted pregnancy [1.2.1]. While it offers additional benefits like regulating periods and reducing acne for some users, it is crucial to be aware of the potential side effects and the small but serious risk of blood clots [1.3.3, 1.4.6]. A thorough consultation with a healthcare provider is essential to determine if Rigevidon is a suitable and safe contraceptive choice based on an individual's health profile and medical history [1.2.1].
Authoritative Link: For detailed patient information, you can refer to the medicines.org.uk electronic medicines compendium (eMC).
