“When we talk about ‘the pill’, the first thing to do is check which type of pill we are talking about. The combined pill (COC) and the progestogen-only pill (POP) work differently,” explains Dr Lee.

“The combined pill (COC) contains two hormones, oestrogen and progestogen. It works by helping to prevent ovulation. Taken perfectly, COC gives over 99% protection against unplanned pregnancy.

“The progestogen-only pill (POP) contains progestogen only. Overall, the progestogen-only pill (POP) also provides 99% protection against unplanned pregnancy.

“Whether it’s COC or POP, another very important factor that affects the reliability of your pill, is how well you take it.

“In clinical trials, women are very well supervised and tend to take their pills perfectly. 

“This means research trials tend to report excellent contraception with very low failure rates of around 1%. 

“However, when the pills are used in the community, with typical everyday use, failure rates are often much higher.”

“The progestogen-only pill (POP) is also known as the mini pill, of which there are two different types.

“The traditional POP contains levonorgestrel (a synthetic hormone) or norethisterone (a synthetic progestogen).

“The more modern POPs all contain desogestrel (synthetic progestogen used in birth control).

“It’s important to understand there is a difference because of the way these two POPs work. 

“The traditional POPs do not always inhibit ovulation. They work predominantly by thickening cervical mucus and making it impenetrable to sperm. 

“To keep this mucus-thickening effect constant means you must take your pill at the same time, and within three hours of the same time, every day. 

“However, the more modern POPs work primarily by inhibiting ovulation. They also thicken cervical mucus, but this is more of a back-up contraceptive effect. 

“All POPs are taken continuously with no seven-day break.”

“You can get both COC or POP from your GP, or the Sexual Health Clinic. Contraception is available on the NHS, and free of charge in the UK,” explains Dr Lee.

“Once you are established on the pill, you may be prescribed up to 12 months’ supply at a time,” adds Dr Lee.

Following the recent announcement from the Medicines and Healthcare products and Regulatory Agency (MHRA) women and people with uteruses of reproductive age may choose to purchase a POP from a pharmacy.

That goes for both those already on a form of contraceptive pill and looking to change and those looking for new contraceptive options.

A daily progestogen-only contraceptive pill, Hana (desogestrel 75 microgram) recently became available to buy from the pharmacy without a prescription.

Those wanting to purchase it will be required to have a consultation with a pharmacist first to ensure it’s appropriate for their personal needs. 

While the pill is still available for free, Hana is another option for some women to consider, depending on their own personal preferences and lifestyle, for example the opportunity not to have to wait for a GP appointment.

The option to purchase the pill over the counter can help to provide more convenient and regular access for some people, who, because of lifestyle preferences are willing to pay for their contraceptive choices.

Visit a pharmacist for professional advice on which contraceptive methods are best for your personal lifestyle and health.

“Yes, you can become pregnant on any form of contraception.

“No contraception gives 100% protection. The pill will only work as well as you are good at taking it!

“Common reasons for getting pregnant on the pill include all the ‘Ds’!

“Didn’t take – forgot to take it.

“Delay – took it later than recommended, or, a delay in starting a new pack of pills.

“Drugs – taking other drugs that might interfere, such as enzyme-inducing drugs, for example, anticonvulsants such as carbamazepine, or the herbal remedy St John’s Wort.

“Diarrhoea and vomiting – generally, if you vomit within two-four hours of taking a POP or a COC, this counts as a missed pill. Another pill should be taken as soon as possible, and the ‘missed pill rules’ followed. 

“If you have severe and protracted diarrhoea, you will need to take additional contraceptive measures whilst you are ill and for the first seven days of your normal pill taking. 

“However, every contraceptive pill may have different suggested duration times classified as a missed pill, and everyone taking a contraceptive pill should check their specific patient information leaflet.

“Sometimes true pill failures do occur.

“If you ever suspect you might be pregnant, it’s always best to do a pregnancy test. 

“This might be if you develop any pregnancy symptoms such as nausea, vomiting, dizziness or breast tenderness. 

“Also, you can experience changes in your period such as irregular periods or stopped periods altogether. But as long as you have been taking the pill as recommended, it is unlikely that you are pregnant. Although, if you generally have a period on your POP, but your periods stop, do a pregnancy test to be sure. 

“When you come off the pill your periods should return.

“If you have stopped the pill but not had a period for three months, I recommend going to see your doctor. 

“Neither COC nor POP will make you infertile or permanently stop your periods. If your periods do not return, this will be for some other cause.

“If you are considering stopping your current pill and do not want to get pregnant, it’s a good idea to decide on a different method of contraception, and prepare to get that method started before you stop your pill. 

“Many women like the idea of Long-Acting Reversible Contraception (LARC), such as coils (the copper IUD, or ’the hormone coil’), implants, or injections. 

“These methods can be fitted and forgotten and are very reliable, with almost no input on the part of the user.

“However, I recommend listening to your doctor’s advice and reading your patient information leaflet to make sure your contraceptive method has started working as it should.”

Weight gain is listed as a potential undesirable effect of desogestrel, however evidence suggests that those who may have put on weight associated with the pill, did not experience significant amount.

“In truth, women’s weight tends to fluctuate whether they take the pill or not. 

“A 2014 Cochrane review looking at COC found only four studies out of 49 that were good enough quality for comparison. There was no evidence that any combined method of contraception – the pill, the patch, or the vaginal ring – has a causal association with weight gain.

“Regarding POP, a 2016 meta-analysis of 22 trials, again found it difficult to make comparisons because of the quality of the evidence. 

“Most studies showed a less than 2kg weight gain over 12 months in women using different types of progestogen-only contraceptives. 

“The authors also concluded that there was little quality evidence of body weight changes associated with the POP.”

“If you miss a pill you need to follow the missed pill rules which are, unfortunately, complicated. You can find a clear explanation on missed combined pills here and missed progestogen-only pills here.”

Details on what you should do if you have missed a pill are available in the product information leaflet. 

If you have any concerns, speak to your pharmacist or GP for advice