Contraceptive Pills Prescribed by UK-Registered Doctors

Oral contraceptive pills fall into two main categories, each with distinct mechanisms, benefits, and risk profiles.

Understanding these differences is essential for making an informed choice with your prescriber.

The combined oral contraceptive (COC) contains both oestrogen (usually ethinylestradiol 20-35 mcg) and a progestogen.

The oestrogen component suppresses follicle-stimulating hormone (FSH), preventing follicular development, while the progestogen suppresses the luteinising hormone (LH) surge, preventing ovulation.

Additional contraceptive effects include thickening of cervical mucus and thinning of the endometrium.

COC formulations are categorised by their progestogen generation:

• 2nd generation: Levonorgestrel (Microgynon 30, Rigevidon) — lowest VTE risk among COCs, FSRH first-line recommendation
• 3rd generation: Desogestrel (Marvelon), gestodene (Femodene) — slightly higher VTE risk (6-8 per 10,000 women-years versus 5-7 for 2nd generation)
• Anti-androgenic: Cyproterone acetate/ethinylestradiol (co-cyprindiol) — used for acne and hirsutism alongside contraception; highest VTE risk in this class
• Newer progestogens: Drospirenone (Yasmin), dienogest (Qlaira) — drospirenone has mild anti-mineralocorticoid properties reducing water retention

The progestogen-only pill (POP) contains a single progestogen without oestrogen.

The traditional POP (norethisterone 350 mcg) works primarily by thickening cervical mucus and must be taken within a strict 3-hour window daily.

The newer desogestrel POP (Cerazette, Cerelle, Feanolla — 75 mcg) additionally inhibits ovulation in 97% of cycles and has a more forgiving 12-hour missed pill window.

The POP is suitable for women who cannot take oestrogen due to:

• Migraine with aura
• History of venous thromboembolism
• BMI above 35
• Age over 35 and smoking
• Breastfeeding (can be started from day 1 postpartum)
• Hypertension (systolic 140-159 mmHg)

Both pill types are over 99% effective with perfect use. With typical use (accounting for missed pills and human error), effectiveness drops to approximately 91%.

Every contraceptive prescription at Dr.

Presc follows the UK Medical Eligibility Criteria for Contraceptive Use (UKMEC), adapted from WHO guidelines by the Faculty of Sexual and Reproductive Healthcare (FSRH).

This framework categorises conditions on a scale from 1 (no restriction) to 4 (unacceptable health risk).

UKMEC Category 4 contraindications for the combined pill (method should not be used):

• Migraine with aura at any age
• Active or past venous thromboembolism (DVT, PE)
• Known thrombogenic mutations (Factor V Leiden, Protein C/S deficiency)
• Ischaemic heart disease or stroke
• Breast cancer (current)
• Severe hepatic cirrhosis or liver tumours
• Major surgery with prolonged immobilisation
• Systolic blood pressure 160 mmHg or above
• Age 35 or above and smoking 15 or more cigarettes daily

UKMEC Category 3 (risks generally outweigh benefits — prescribe only with specialist guidance):

• BMI 35-39 (Category 4 if BMI 40+)
• Age 35 and smoking fewer than 15 cigarettes daily
• Adequately controlled hypertension
• Migraine without aura in women over 35
• Multiple cardiovascular risk factors (diabetes, hypertension, smoking, obesity combined)

The progestogen-only pill has very few absolute contraindications, primarily current breast cancer and severe decompensated cirrhosis.

This makes it the default oral option for women with oestrogen-related risk factors.

Blood pressure measurement is required before initiating the combined pill. FSRH guidance mandates a blood pressure reading below 140/90 mmHg.

For online consultations, patients must provide a recent blood pressure reading (taken within the past 12 months) from their GP, pharmacy, or home monitor.

VTE risk assessment is central to safe COC prescribing:

• Background VTE risk in women of reproductive age: 2 per 10,000 women-years
• COC with levonorgestrel: 5-7 per 10,000
• COC with desogestrel/gestodene: 6-12 per 10,000
• Pregnancy itself carries a VTE risk of 29 per 10,000

Our prescribers perform a comprehensive risk assessment including family history, BMI, smoking status, and migraine history before issuing any COC prescription.

This screening is non-negotiable, regardless of whether the patient has previously taken the pill elsewhere.

Oral contraceptives offer well-documented non-contraceptive health benefits that influence prescribing decisions, particularly for women seeking management of specific conditions alongside birth control.

Menstrual cycle regulation is one of the most common non-contraceptive reasons for COC use.

The pill produces predictable withdrawal bleeds (or no bleeds when taken continuously) and reduces menstrual blood loss by 40-50%, making it a first-line treatment for heavy menstrual bleeding.

Dysmenorrhoea (period pain) improves in approximately 70-80% of women on the COC due to suppression of prostaglandin production.

Acne and hirsutism respond to the anti-androgenic effects of certain COC formulations.

The oestrogen component increases sex hormone-binding globulin (SHBG), which reduces circulating free testosterone.

Co-cyprindiol (Dianette) contains cyproterone acetate, a potent anti-androgen, but is reserved for moderate-to-severe acne unresponsive to topical treatment.

Desogestrel- and drospirenone-containing pills also have beneficial effects on androgen-mediated skin conditions.

Cancer risk reduction:

• Ovarian cancer risk decreases by 20% per 5 years of COC use, with protection lasting 15-20 years after discontinuation
• Endometrial cancer risk is halved with 5 or more years of COC use
• Colorectal cancer risk is reduced by approximately 20%
• These protective effects are among the most clinically significant long-term benefits of the COC

Endometriosis and adenomyosis symptoms are managed with continuous COC use, suppressing ovulation and reducing the cyclical hormonal stimulation that drives ectopic endometrial tissue growth.

NICE recommends the COC as a first-line medical treatment for endometriosis-related pain.

Polycystic ovary syndrome (PCOS) management frequently includes the COC to regulate cycles, reduce androgens, and provide endometrial protection against the hyperplasia that results from unopposed oestrogen in anovulatory women.

Potential risks must be balanced against these benefits:

• Small increase in breast cancer risk during use and for 5-10 years after stopping (relative risk 1.2)
• Cervical cancer risk modestly increased with long-term use (over 5 years)
• These risks are generally small in absolute terms and diminish after discontinuation

Correct pill-taking maximises contraceptive effectiveness and minimises unintended pregnancies.

Adherence patterns directly determine whether you achieve the 99% efficacy of perfect use or the 91% of typical use.

Combined pill — standard 21/7 regimen:

• Take one pill at the same time each day for 21 days
• Take a 7-day pill-free break (or placebo pills if using an everyday preparation)
• Contraceptive cover continues during the break provided you start the next strip on time
• The pill-free interval is the highest-risk time for conception — extending it beyond 7 days is the most common cause of contraceptive failure

Continuous or extended regimens are increasingly recommended by the FSRH. Taking 3 strips back-to-back (63 days), then a 4-7 day break, reduces breakthrough bleeding while maintaining efficacy.

Some women prefer to eliminate withdrawal bleeds entirely by taking the pill continuously, which is safe and endorsed by FSRH guidance.

Progestogen-only pill:

• Take one pill at the same time every day with no break
• For desogestrel POPs (Cerazette, Cerelle): a pill is "missed" if taken more than 12 hours late
• For traditional POPs (norethisterone): a pill is "missed" if taken more than 3 hours late

What to do if you miss a pill (COC):

• 1 missed pill (up to 48 hours late): take it as soon as remembered, continue the rest of the pack normally, no additional contraception needed
• 2 or more missed pills (48+ hours late): take the most recent pill, skip any earlier missed pills, use condoms for the next 7 days. If the missed pills occurred in week 1 and unprotected sex happened, consider emergency contraception. If in week 3, omit the pill-free break and start the next strip immediately.

Interactions that reduce pill efficacy:

• Enzyme-inducing drugs: carbamazepine, phenytoin, rifampicin, St John's Wort, some antiretrovirals
• Vomiting within 2 hours of taking the pill (repeat the dose)
• Severe diarrhoea lasting more than 24 hours
• Broad-spectrum antibiotics do NOT reduce COC efficacy (a common misconception) except rifampicin

FSRH guidance recommends setting a daily phone alarm and keeping pills in a visible location as simple adherence strategies. Pharmacy dispensing of 3-6 months' supply reduces the risk of running out.

Ongoing monitoring ensures that oral contraception remains safe throughout use. FSRH recommends an initial review 3 months after starting a new pill, then annually thereafter.

Annual review should include:

• Blood pressure measurement (COC users only — discontinue if consistently above 140/90 mmHg)
• BMI recalculation (COC contraindicated at BMI 40+; UKMEC 3 at BMI 35-39)
• Smoking status update (COC contraindicated in smokers aged 35+)
• Migraine assessment (new-onset aura is an indication to stop the COC immediately)
• Review of any new medications or diagnoses that alter eligibility
• Cervical screening reminder (pill use does not alter screening intervals but long-term COC use slightly increases cervical cancer risk)

Stop the pill and seek urgent medical advice if you experience:

• Sudden severe headache, especially with visual disturbance or one-sided weakness (possible stroke)
• Calf pain and swelling, unexplained breathlessness, or chest pain (possible DVT/PE)
• Sudden partial or complete loss of vision
• Severe abdominal pain
• Jaundice or hepatitis symptoms
• First-ever migraine with aura
• Blood pressure above 160/95 mmHg on repeated measurement

Common side effects that usually settle within 2-3 months:

• Breakthrough bleeding (affects 30-50% in the first 3 months, resolving in most by month 4)
• Breast tenderness
• Headache (non-migrainous)
• Mood changes (evidence on depression risk is mixed; a Danish cohort study suggested a small increase in antidepressant use among COC users, but the absolute risk increase was modest)
• Nausea (taking the pill with food or at bedtime helps)

Switching pills: If side effects persist beyond 3 months or are intolerable, your prescriber can switch formulations.

Moving to a lower oestrogen dose (20 mcg instead of 30 mcg) reduces oestrogen-related side effects. Switching progestogen type may improve mood-related or androgenic side effects.

Transitioning from COC to POP eliminates oestrogen-related risks entirely.

When ordering repeat prescriptions through Dr. Presc, the consultation includes a condensed annual review checklist to ensure safety criteria are still met.

Blood pressure confirmation is required for COC renewals.