Choosing an oral contraceptive can feel confusing when the packets on a pharmacy shelf all look broadly similar. In the UK, the contraceptive pill falls into two broad families: combined pills and progestogen-only pills. They rely on different hormones, they work in slightly different ways, and — importantly — they carry different cautions. This article explains how the two compare so you can have a more informed conversation with a clinician about what might suit your body, your medical history and your lifestyle.

What "combined" and "progestogen-only" mean

The names describe the hormones inside each pill. A combined pill contains two hormones — an oestrogen (usually a synthetic form called ethinylestradiol) and a progestogen. A progestogen-only pill, often called the mini pill, contains just a single progestogen and no oestrogen at all. That one difference is the reason the two behave differently in the body and suit different people.

Both are widely used across the UK, and clinical guidance for prescribers is published by the Faculty of Sexual & Reproductive Healthcare (FSRH), with prescribing detail set out in the British National Formulary (BNF). Combined pills come in familiar brands such as Microgynon, while desogestrel-based progestogen-only pills such as Cerelle are examples of the mini pill. The specific product is far less important than whether the type is appropriate for you.

How each works to prevent pregnancy

Combined pills work mainly by preventing ovulation — the release of an egg — while also thickening cervical mucus and thinning the womb lining. Because they reliably suppress ovulation, they offer a familiar monthly bleeding pattern and are often chosen by people who also want more predictable cycles.

Progestogen-only pills work primarily by thickening cervical mucus so sperm cannot pass through easily, and some (particularly desogestrel-based ones) also stop ovulation in most cycles. Bleeding patterns on the mini pill are more variable — periods may become lighter, irregular or stop altogether, which is normal but can take some getting used to.

It is worth saying that neither approach is inherently "better" than the other. They are simply different tools that suit different people at different stages of life. Some people value the predictable withdrawal bleed that a combined pill can offer, or the non-contraceptive benefits it can bring, such as helping with heavy or painful periods and, for some, acne. Others prefer or need an oestrogen-free option. The right choice is the one that matches your health, your priorities and your day-to-day routine.

How effective are they?

Both the combined pill and the progestogen-only pill are highly effective when taken correctly and consistently. In everyday "typical use", however, effectiveness is a little lower than the "perfect use" figures often quoted, largely because pills can be missed, taken late, or affected by vomiting, severe diarrhoea or certain interacting medicines. This is why remembering to take your pill — and knowing what to do if you miss one — matters as much as which type you are on. If reliably remembering a daily pill is difficult, a clinician can also talk you through longer-acting methods that do not depend on daily dosing, though those sit outside the scope of this comparison.

Which one might suit you

Because the combined pill contains oestrogen, it carries a small increase in the risk of blood clots and is not recommended for everyone. UK guidance recognises several situations where oestrogen-containing contraception is usually avoided, and where a progestogen-only method may be considered instead. These include:

  • Migraine with aura — the visual or sensory warning signs some people get before a migraine. This is a well-recognised reason to avoid combined contraception.
  • Smoking over the age of 35 — the combination of oestrogen, smoking and older age raises cardiovascular risk.
  • A raised BMI — a higher body mass index is one of several factors that can shift the balance of risk.
  • Raised blood pressure or a personal or strong family history of blood clots, stroke or certain heart conditions.

None of these points automatically rules the combined pill in or out on their own. They are pieces of a fuller picture that a clinician weighs up with you. If a combined pill is not suitable, progestogen-only options are often appropriate because they do not contain oestrogen — but suitability is still assessed individually.

Timing windows and missed pills

One practical difference between the two families is how forgiving they are about timing. Combined pills are usually taken daily for 21 days followed by a break, or continuously depending on the regimen, and there is some leeway if a pill is late. Progestogen-only pills have stricter timing windows: traditional (older) progestogen-only pills need to be taken within about three hours of the same time each day, whereas desogestrel-based pills allow a window of around 12 hours. Missing a pill, or taking it outside its window, can reduce protection, so it is worth knowing which type you are on and checking the patient information leaflet for what to do if you miss one.

Common side effects and the first few months

Most people settle onto either type of pill without major problems, but the first two to three months are often when the body is adjusting. Combined pills can be associated with breast tenderness, headaches, mood changes, nausea or breakthrough bleeding early on, most of which tend to ease over time. Progestogen-only pills are most commonly associated with changes in bleeding pattern — from irregular spotting to no bleeding at all — as well as similar hormonal effects in some people.

These early side effects are usually not a reason to stop straight away, but they are worth discussing with a clinician, especially if they are severe or persistent. Sometimes switching to a different formulation or the other type of pill resolves the problem. If you experience any of the warning symptoms in the safety box above, seek advice promptly rather than waiting.

Irregular bleeding is the change people most often want reassurance about, particularly on the progestogen-only pill. In the first few months it is common and usually settles, but any new bleeding pattern that appears after things had been stable, bleeding after sex, or bleeding that is heavy or persistent is worth mentioning to a clinician so other causes can be considered. It is also worth knowing that some medicines — including certain antibiotics, epilepsy treatments and the herbal remedy St John's Wort — can interact with hormonal contraception, which is another reason to keep your clinician informed about everything you take.

Neither method protects against STIs

It is worth being clear on one point that applies equally to both families: the contraceptive pill prevents pregnancy but does not protect against sexually transmitted infections. Condoms remain the main way to reduce STI risk, and regular testing is sensible if you have new or multiple partners. You can read more in our guide to STI testing in the UK.

What a clinician will check at consultation

A contraception consultation is usually straightforward. A clinician will typically ask about your medical history, any migraines and their type, whether you smoke, your family history of clots or cardiovascular disease, and any medicines you take that might interact. Blood pressure is checked before starting a combined pill, and your BMI may be noted. From there, your clinician can talk through whether a combined or progestogen-only method fits your circumstances, and review it periodically as your health or life stage changes.

Contraception is rarely a permanent decision — many people switch types over the years, and that is completely normal. If you are approaching your forties or noticing new symptoms, you may also want to read our overview of menopause and treatment pathways, since contraceptive needs often change around that time. The most important thing is that the method you use is one a clinician has confirmed is appropriate for you.