Cyproterone acetate + Ethinylestradiol (Combined Oral Contraceptive)

Cyproterone acetate and ethinylestradiol is a combined oral medicine used for contraception and, in some cases, to treat hormonal conditions related to higher androgen (male-hormone) effects. In Australia, products containing these ingredients are prescription medicines and may be supplied as tablets taken by mouth.

This page explains how the medicine works, how it is used, key safety points, interactions (including with alcohol and other medicines), and what to expect in everyday use.

Basic product information

• Active ingredients: Cyproterone acetate + ethinylestradiol
• Medicine type: Combined oral contraceptive (COC)
• How it’s taken: Tablets by mouth, typically once daily
• Common brands: Availability varies by supplier and formulation
• What it may be used for: Contraception; treatment of androgen-related symptoms in selected patients as advised
• Notable component: Cyproterone acetate (a progestogenic anti-androgen) + ethinylestradiol (an oestrogen)

How it works (mechanism of action)

Cyproterone acetate + ethinylestradiol prevents pregnancy and can improve androgen-related symptoms through multiple effects:

• Prevents ovulation: The oestrogen and progestogenic components reduce the release of gonadotropins from the brain (notably LH), suppressing ovulation.
• Thickens cervical mucus: This makes it harder for sperm to enter the uterus.
• Alters endometrial (uterine lining) stability: Changes in the uterine lining can reduce the likelihood of implantation.
• Anti-androgen effects (cyproterone acetate): Cyproterone acetate helps counter the effects of androgens on the skin and scalp, which may improve acne and other symptoms related to androgen excess.
• Regulates hormone-related cycles: Many people experience more regular bleeding patterns while taking combined pills.

Typical use in practice

Depending on individual circumstances, clinicians may recommend this medicine for:

• Contraception (to prevent pregnancy).
• Androgen-related conditions in selected people, such as:
  • Moderate to severe acne (particularly when androgen-sensitive)
  • Hirsutism (excess hair growth in androgen-sensitive areas)
  • Other hormonally driven symptoms as assessed clinically

Important: The suitability of this combination varies between individuals. The risks and benefits depend on factors such as age, smoking status, migraine history, blood pressure, and personal/family clotting risk.

Dosing and timing

Common dosing approach: Most combined oral contraceptives containing these hormones are taken as a daily tablet regimen. Many formulations use either a 21-day active tablet schedule followed by a break, or a continuous/extended schedule depending on the specific product.

General timing advice:

• Take one tablet once daily at about the same time each day.
• If you miss a dose, follow the missed-dose instructions in the product leaflet (instructions can vary by formulation and how many pills are missed).
• Use additional contraception (e.g., condoms) during the window when missed pills reduce contraceptive reliability.

When to start: People commonly start at the beginning of a menstrual period or using a clinician-guided start strategy. If you start not on day 1 of your cycle, you may need backup contraception for a period.

How long it takes to work for non-contraceptive benefits:

• Contraception: Effective when taken correctly and in the right starting conditions.
• Acne/hirsutism: Improvements often take several months. Early changes can appear in the first 2–3 months, with fuller results after 4–6 months (or longer), depending on the condition.

Pharmacokinetics (how the body handles it)

Understanding pharmacokinetics helps explain why consistent daily dosing matters and why missed tablets may reduce effectiveness.

Absorption

• Ethinylestradiol is absorbed after oral administration and undergoes first-pass metabolism in the liver.
• Cyproterone acetate is also absorbed orally and similarly experiences metabolism through hepatic pathways.

Distribution

• Both hormones bind significantly to plasma proteins (including sex hormone–binding globulins for oestrogens), which influences circulating levels and duration of effect.

Metabolism

• Both components are primarily metabolised in the liver through enzymatic pathways (including CYP-mediated metabolism), producing metabolites that are then cleared.
• Certain medicines that affect liver enzymes may reduce hormone levels, increasing risk of contraceptive failure or breakthrough bleeding.

Elimination

• Metabolites are eliminated mainly via urine and bile routes.
• Because active hormones have biologically relevant half-life characteristics, steady daily use helps maintain consistent hormone exposure.

Food interactions

For most people, food does not significantly affect absorption of combined oral contraceptives. Tablets can generally be taken with or without food.

• Choose a time that suits your day (e.g., with breakfast or dinner) to support adherence.
• If you have a stomach upset (vomiting or severe diarrhoea), absorption may be reduced—consider backup contraception as advised in the leaflet.

Alcohol and medicine interactions

Alcohol does not typically directly “cancel out” combined oral contraceptives in the same way as certain medications (like some enzyme inducers). However, alcohol can affect adherence and may worsen some side effects.

• Adherence risk: If alcohol leads to missed tablets, contraceptive effectiveness can decrease.
• Side effects: Nausea, breast tenderness, headache, and dizziness may be more noticeable with alcohol in some people.
• Vomiting after heavy drinking: If vomiting occurs soon after taking the tablet, the dose may not have been absorbed—check the missed-dose guidance.

Practical tip: If you plan to drink alcohol, set an alarm and take your tablet at a consistent time earlier in the day or with a meal you will complete.

Indications and who should consider extra caution

Cyproterone acetate + ethinylestradiol is indicated for:

• Contraception
• Selected androgen-related conditions where the clinician determines the benefits outweigh risks

Extra caution / may be unsuitable for people with certain conditions. Discuss risk factors with a healthcare professional, especially if you have:

• A history of blood clots (venous thromboembolism) or known clotting disorders
• Known cardiovascular risk factors such as uncontrolled high blood pressure
• Migraine with aura
• Smoking (particularly age 35 and over)
• Severe liver disease or liver tumours
• Known or suspected hormone-dependent cancers (case-by-case assessment)
• Unexplained vaginal bleeding

Because this medicine contains an oestrogen component, the blood clot risk depends on individual risk factors. Always seek urgent medical attention for symptoms suggestive of a clot (see “Safety profile” below).

Safety profile and important warnings

Like all medicines, cyproterone acetate + ethinylestradiol can cause side effects. Many people tolerate it well, but some risks are serious and require prompt attention.

Common side effects

• Nausea or stomach discomfort
• Breast tenderness
• Headache
• Mood changes
• Breakthrough bleeding (spotting), especially in the first few months
• Changes in libido
• Fluid retention

Serious risks (seek urgent care)

Combined oral contraceptives increase the risk of blood clots compared with not using combined pills. The risk is greatest during the first months of use and after restarting after a break.

• Signs of a clot in the lung (pulmonary embolism): sudden shortness of breath, chest pain (worse when breathing in), coughing blood, fainting
• Signs of a clot in the leg (deep vein thrombosis): swelling in one leg, pain or tenderness in one leg, warmth or redness
• Signs of a stroke: face drooping, arm weakness, speech difficulty, sudden severe headache, sudden vision changes
• Signs of a heart attack: chest discomfort/pressure, pain spreading to arm/jaw, unusual sweating, nausea

Get medical help immediately if any of these occur.

Other important cautions

• Jaundice or severe liver problems: yellowing of skin/eyes, dark urine, severe abdominal pain
• Severe migraine worsening or new migraine with aura: may require stopping and assessment
• High blood pressure: may develop or worsen—regular monitoring may be advised
• Cholestasis or gallbladder issues: symptoms such as right upper abdominal pain or pruritus may occur

Medicine interactions (including enzyme-inducing medicines)

Some medicines can reduce the effectiveness of combined oral contraceptives by increasing hormone metabolism in the liver. This can lead to breakthrough bleeding and contraceptive failure.

Examples of medicines that may interact

• Antiseizure medicines (some examples include carbamazepine, phenytoin, topiramate at higher doses)
• Antituberculosis medicines (e.g., rifampicin)
• Some HIV and hepatitis medicines (interaction depends on regimen)
• Some antifungals (for example, griseofulvin)
• Herbal preparations such as St John’s wort

Antibiotics: Most common antibiotics do not reliably reduce contraceptive effectiveness. However, exceptions exist, and if you experience vomiting/diarrhoea or breakthrough bleeding, follow the leaflet and consider backup contraception.

Always check: If you start or stop any medicine (including over-the-counter products), verify interaction risk and whether backup contraception is needed.

Practical use tips for daily life

• Take at the same time daily: Consistency improves effectiveness and reduces spotting.
• Use a reminder system: Smartphone alarm, calendar, or a blister pack organiser.
• Keep track of missed tablets: Mark your pack or keep a daily note until you’re confident.
• Manage vomiting/diarrhoea: If you vomit soon after taking a tablet or have severe diarrhoea, your dose may not have been fully absorbed—follow missed-dose guidance.
• Birth control backup: If missed doses occur or interacting medicines are used, use condoms until effectiveness is restored.
• Regular reviews: Consider periodic checks for blood pressure and assessment of migraine or other risk factors.

Pharmacovigilance: when to stop and seek advice

Do not stop abruptly without advice if stopping could lead to unintended pregnancy—unless serious symptoms occur. Seek urgent medical help if you suspect a clot or stroke.

Contact a healthcare professional promptly if you experience:

• Unusual severe headaches
• Visual disturbances
• Persistent severe abdominal pain
• Unexplained heavy bleeding
• Symptoms of liver problems (yellowing skin/eyes)

Alternative options

Contraception and treatment of androgen-related symptoms can be approached with multiple options depending on your goals, medical history, and preferences.

Contraceptive alternatives

• Progestogen-only pills (suitable for some people who cannot take oestrogen)
• Long-acting reversible contraception:
  • Hormonal intrauterine device (IUD)
  • Copper IUD
  • Implant
• Barrier methods (condoms, diaphragm)

For acne/hirsutism

• Other hormonal strategies (choice depends on risk profile)
• Non-hormonal acne treatments (topical therapies, antibiotics, etc.) may be combined with dermatology plans
• In some cases, anti-androgen treatments may be considered—your clinician will weigh clot and other risks

Choosing an alternative: The “best” option depends on clot risk, smoking status, migraine pattern, bleeding preferences, and treatment goals.

Australia: market and legal context

In Australia, combined oral contraceptives are regulated medicines. Products containing cyproterone acetate and ethinylestradiol are generally available through prescription pathways and dispensed by licensed pharmacies.

Availability may vary by:

• Manufacturer supply and pack size
• Formulation differences (e.g., active tablet count and hormone strength)
• Therapeutic guideline updates and local prescribing patterns

Guidance and monitoring: Clinicians and pharmacists commonly follow national and international risk-benefit frameworks for hormonal contraception, including clot risk assessment and contraindication screening.

Recent guidance (general principles)

While specific product guidance can change, the following principles commonly reflect contemporary Australian contraceptive safety practice:

• Individualised risk assessment before starting combined pills.
• Attention to clot risk factors, especially smoking, age, migraine with aura, and personal/family clot history.
• Review of interacting medicines, including enzyme inducers and herbal products like St John’s wort.
• Early evaluation of new symptoms such as severe headache, breathing difficulties, or leg swelling.

If you have recently started or are re-starting the medicine, consider discussing follow-up and risk factors with a healthcare professional.

Delivery and availability (online pharmacy)

Online pharmacies in Australia typically offer:

• Discreet packaging
• Home delivery to eligible areas
• Delivery updates via email or SMS

Availability: Stock can vary between brands and pack sizes. If a specific pack is unavailable, a pharmacy may offer alternatives where appropriate (for example, a different formulation) consistent with clinical guidance.

Storage: Store tablets below 30°C (unless the leaflet specifies otherwise), protect from moisture, and keep out of reach of children.

FAQ

1) Is cyproterone acetate + ethinylestradiol effective for contraception?

Yes, when taken correctly and started under appropriate conditions, it is effective. Missed tablets, vomiting/diarrhoea soon after dosing, and interacting medicines can reduce effectiveness—so follow missed-dose and interaction guidance carefully.

2) How quickly does it start working?

Timing depends on when you start relative to your menstrual cycle and the specific regimen. Your product leaflet provides exact instructions. If unsure, use backup contraception until you’re confident you’re protected.

3) What if I miss a tablet?

Missed-dose instructions vary by formulation and how many tablets are missed. Refer to the package leaflet for step-by-step guidance, and use condoms/backup contraception during the period when protection may be reduced.

4) Can I take it with food?

Generally, yes. Food usually does not significantly affect absorption. Take it consistently at a time you can maintain daily.

5) Does alcohol make it stop working?

Alcohol does not usually directly cancel the medicine’s effect. However, heavy drinking can increase the likelihood of missed tablets and vomiting, which may affect absorption. If vomiting occurs soon after your tablet, follow missed-dose guidance.

6) Are there medicines I should avoid?

Some medicines (including certain antiseizure medicines, rifampicin, some HIV/hepatitis regimens, and herbal St John’s wort) may reduce hormone levels. Always check interactions with a pharmacist.

7) What side effects are common?

Nausea, breast tenderness, headaches, mood changes, and breakthrough bleeding can occur, particularly during the first months. Many side effects lessen over time.

8) What symptoms mean I should seek urgent help?

Seek urgent medical care for signs of blood clots or stroke, such as sudden shortness of breath, chest pain, one-sided leg swelling/pain, severe sudden headache, weakness on one side, or speech/vision changes.

9) Can it help acne or hair growth?

It may help androgen-related acne and hirsutism in selected individuals. Improvements often take months, and the best results are achieved with consistent use and follow-up.

10) What are practical ways to improve adherence?

Use alarms, keep the pack visible, take your dose with a routine meal, and plan ahead for travel or days when you might be unwell.

Summary table

Always read the consumer medicine information leaflet provided with your specific pack for detailed instructions, including missed-dose guidance and what to do in special situations. If you’re unsure whether this medicine is appropriate for you, speak with a healthcare professional or pharmacist.