What is the Pill?

The combined oral contraceptive pill—often just called “the pill”—contains artificial versions of the hormones oestrogen and progesterone, which are naturally produced in the ovaries. 

At a Glance: The Combined Pill

  • When taken correctly, the pill is over 99% effective at preventing pregnancy. Fewer than 1 in 100 people who use the combined pill correctly will become pregnant in a year. Other methods—like the IUD, implant, and injection—are even more effective. 
  • Typically, the pill is taken once a day for 21 days, followed by a 7-day break, during which a period-like bleed occurs. The next pill pack starts after the 7-day break, even if the bleeding hasn’t stopped. 
  • It’s important to take the pill at around the same time each day. Missing a dose, vomiting, or having severe diarrhoea can reduce its effectiveness and increase the chance of pregnancy. 
  • Some medications can also reduce the pill’s effectiveness. Always check with a healthcare provider if you’re taking other medication. 
  • The pill may also help with heavy or painful periods, premenstrual syndrome (PMS), or endometriosis. 
  • Common side effects include mood changes, nausea, breast tenderness, and headaches. There's no evidence the pill causes weight gain. 
  • There is a very small risk of more serious side effects, such as blood clots or certain cancers. 
  • The combined pill may not be suitable for people over 35 who smoke, or for those with certain medical conditions. 
  • The pill does not protect against sexually transmitted infections (STIs), so using a condom as well is recommended for STI protection. 

How the Pill Prevents Pregnancy 

The pill prevents ovulation (the release of an egg). It also: 

  • Thickens cervical mucus, making it harder for sperm to reach an egg 
  • Thins the womb lining, reducing the chance of a fertilised egg implanting 

Although over 99% effective when used correctly, the pill can be less effective if taken irregularly. Some people may find it difficult to take it at the same time every day. Other contraceptive methods—like the IUD, implant, or injection—can be more reliable for some users. 

Types of Combined Pill 

There are many brands, but they fall into three main categories: 

Monophasic 21-Day Pills 

Each pill contains the same hormone dose. One is taken daily for 21 days, followed by 7 days off. Examples: Microgynon, Marvelon, Yasmin, Cilest. 

Phasic 21-Day Pills 

Pills contain varying hormone levels across the cycle. They must be taken in the correct order. Example: Logynon. 

Every Day (ED) Pills 

A pack contains 21 active pills and 7 inactive (placebo) pills. Taken daily for 28 days with no break between packs. Example: Microgynon ED. 

Always follow the instructions that come with your pill pack. Ask a GP, nurse, or pharmacist if you’re unsure. 

How to Take the Pill 

21-Day Pills: 

  • Take your first pill marked with the correct day. 
  • Continue daily at the same time until the pack is finished. 
  • Take no pills for the next 7 days (you will likely experience bleeding). 
  • Start the next pack on the 8th day—regardless of whether you’re still bleeding. 

Every Day (ED) Pills: 

  • Start with the first active pill in the pack marked “start.” 
  • Continue daily in the correct order until the pack is finished. 
  • You will bleed during the 7 inactive pills. 
  • Begin your next pack immediately after the last. 

Starting the Pill 

Most people can start the pill at any point in their cycle. You may need additional contraception when first starting, depending on timing. 

  • Starting on Day 1 of your period: You’re protected straight away. 
  • Starting on Day 5 or earlier: Usually still protected unless your cycle is shorter than 23 days. 
  • Starting after Day 5: You’ll need additional contraception (e.g., condoms) for 7 days. 

If there’s any chance you’re already pregnant, take a pregnancy test 3 weeks after the last unprotected sex. 

Missed Pills, Vomiting, or Diarrhoea 

  • If you miss a pill, it may reduce effectiveness. What to do depends on when and how many were missed. 
  • Vomiting within 2 hours of taking the pill? Take another one. 
  • Severe diarrhoea may also impact effectiveness—use backup contraception and check with a healthcare provider. 

Who Can Use the Pill? 

Most people can take the pill up to menopause, but it’s not suitable for everyone. Don’t use the pill if you: 

  • Are pregnant 
  • Are 35 or older and smoke or quit less than a year ago 
  • Have certain health conditions (e.g., blood clots, certain cancers, severe migraines) 

A healthcare provider can help determine if the pill is suitable for you. 

After Birth, Miscarriage, or Abortion 

  • After giving birth (not breastfeeding): Can usually start on Day 21. 
  • Breastfeeding: Wait until 6 weeks after birth. 
  • After miscarriage or abortion: Start within 5 days for immediate protection. 

Advantages and Disadvantages of the Pill

Advantages Disadvantages

Doesn’t interrupt sex 

Can cause temporary side effects like headaches or nausea 
Regulates, lightens, and reduces period pain  May increase blood pressure 
May reduce acne and PMS  Doesn’t protect against STIs
Lowers risk of ovarian, womb, and colon cancers  Linked to small risk of serious conditions (e.g., blood clots, breast cancer)
May protect against pelvic inflammatory disease and fibroids   

 

Interactions With Other Medicines 

Some medicines reduce the effectiveness of the pill. These include: 

  • Rifampicin/rifabutin (antibiotics) 
  • Certain epilepsy medicines 
  • St John’s Wort (herbal remedy) 
  • Some HIV medications 

Always consult a doctor, nurse, or pharmacist about any medicine you’re taking. 

Risks 

Blood Clots 

Oestrogen may increase clotting risk, which can lead to deep vein thrombosis (DVT), pulmonary embolism, stroke, or heart attack. Risk is low but should be assessed by a doctor. 

Cancer 

There is a slight increase in the risk of breast and cervical cancers while taking the pill, but the risk returns to normal 10 years after stopping. The pill also reduces the risk of ovarian, womb, and colon cancer. 

Where to Get the Pill 

Contraception is free through the NHS in the UK. You can get it from: 

If You’re Under 16 

Services are free and confidential—even for those under 16. A healthcare professional won’t tell parents/carers unless there's a serious concern about safety or wellbeing, and they'll usually discuss this with you first. 

Contraception