Taking two medications at the same time is often safe, but not always. Sometimes, it can cause one or both of the medications to not work properly - or even not work at all. Hormonal contraceptives can be affected by this. It's important to be aware of the medications that can affect your contraception, such as antibiotics, beta blockers, and drinking alcohol.
Among others, the pill, the patch, the implant and the vaginal ring are all hormonal contraceptives. They can be affected by taking other medications. Some hormonal contraceptives can also alter how other medications work as well. If you’re unsure about how your medication might affect birth control, speak to a pharmacist who can give you specialised advice.
For now, let’s focus on the medications that can affect birth control pills such as the progesterone-only pill (POP) and the combined pill.
What medications affect the pill?
If you’re taking a medication that lists vomiting or diarrhoea as possible side effects, your contraceptive pill might not work properly. This is because the pill might leave the body in diarrhoea or vomit before it gets a chance to work. If this happens, follow the advice set out in the patient information leaflet that came with your birth control. You may need to take another pill.
Other medicines can make your body process contraceptive hormones faster . These include enzyme-inducing medications that increase the levels of enzymes in your body. They can reduce the levels of contraceptive hormones in your blood, limiting the effectiveness of your birth control.
Some enzyme-inducing medications that can affect your birth control pill include:
- The antibiotics rifampicin and rifabutin
- Some epilepsy medications
- Some antiretroviral drugs used in HIV treatment
- St John’s Wort (a herbal remedy)
When starting a new medication, it’s important to let your pharmacist or doctor know what other medications you are taking. They may suggest an alternative method of birth control if you are taking a medication that might affect your contraception.
Another medication that can affect your contraceptive pill is called ulipristal acetate. It's found in some forms of emergency contraception. Ask your pharmacist or doctor if your emergency contraceptive contains ulipristal acetate. If it does, taking a regular contraceptive pill such as Lovima® sooner than five days later could cause the emergency contraceptive to fail, or the usual contraception to be less effective.
They both target the same progesterone receptor, so if your contraceptive pill binds to the receptor, the ulipristal acetate cannot. This means that you may be protected going forward, but there is still a chance that the emergency contraceptive or your regular contraceptive may fail.
Do beta blockers affect the contraceptive pill?
Beta blockers aren’t thought to affect the contraceptive pill’s effectiveness, although they can interact with other medications. However, some beta blockers may cause nausea and vomiting, which can in turn impact how well birth control works.
Some types of hormonal birth control aren't recommended if you have high blood pressure - a condition for which beta blockers are often prescribed. If this is the case, you may be offered a different contraceptive. Speak to your pharmacist or doctor if you're worried about beta blockers affecting your contraception. They can suggest alternatives that might be more suitable.
Does the contraceptive pill work when on antibiotics?
As previously mentioned, some antibiotics may alter the effectiveness of your contraceptive pill . These are rifampicin and rifabutin. They're less common than penicillin and other antibiotics. If you use rifampicin or rifabutin at the same time as a hormonal contraceptive, you may get pregnant.
Some people only need to take antibiotics for a short time. If so, you may find it best to temporarily double up on contraception by using a condom as well as your birth control pill to decrease your chances of getting pregnant. You should do this for at least twenty-eight days after finishing the antibiotics.
It might be better to switch to a different form of contraception if you need to take your antibiotics for longer. Speak to a pharmacist or doctor who can help you decide which method of birth control is best for you.
All other antibiotics are unlikely to affect your contraceptive pill . This is because they aren't enzyme-inducing. However, it's always best to speak to a pharmacist or doctor. You should also read the leaflet that comes with your medication. If your antibiotics cause vomiting or diarrhoea, this may affect your birth control.
Does thrush medication affect the pill?
Thrush is usually treated with antifungal medications. Although there’s no evidence to suggest that these affect how contraceptive pills work, antifungal medications may affect other forms of contraception. These include condoms, diaphragms and spermicides. Therefore, if you use a barrier method in addition to the pill, it’s worth being aware that it may be less effective while you’re using antifungal medication.