Contraception during chemotherapy

Yes. Anyone who could become pregnant, or who could make a partner pregnant, should use reliable contraception throughout chemotherapy and for a period afterwards that your oncologist will advise. Chemotherapy medicines can harm a developing baby, especially in the early weeks of pregnancy, and they can also damage sperm and eggs that are maturing during treatment. It is a common and understandable mistake to assume that chemotherapy makes pregnancy impossible. Periods often stop or become irregular during treatment, and sperm counts often fall, but neither means that pregnancy cannot happen. Women can still release an egg without a regular period, and men can still produce some sperm even when counts are low. Unplanned pregnancies during cancer treatment do happen, and they create very difficult decisions for families.

The right method depends on your cancer, your treatment and your blood counts. Condoms are usually recommended for men and women during treatment, both to prevent pregnancy and because small amounts of chemotherapy can be present in semen and vaginal fluids for a short time after each dose. Hormone-containing methods, such as the pill, patches, injections or some coils, may not be suitable for people with hormone-sensitive cancers, such as many breast cancers, or for those at raised risk of blood clots. A copper coil is a hormone-free option for some women, but fitting it may need to be timed around blood counts to reduce the risk of infection or bleeding. Tummy upsets and vomiting can make the pill less reliable. For all these reasons, contraception during chemotherapy should be planned with your oncology team rather than continued without discussion.

Ask before the first cycle

Discuss contraception at the same appointment where treatment is planned, so a method is in place from the first dose.

Partners need to know

Contraception is a shared responsibility. Partners should understand why it matters and how long it is needed.

Pregnancy tests may be done

Women who could be pregnant are often asked for a pregnancy test before treatment begins. This is routine care.

It cannot tell you which method is safe for you or exactly how long to continue after treatment. That depends on the medicines you receive, your cancer type, your blood counts and your wider health. Different treatments have different advice, and guidance for men and women can differ. Your oncologist will give advice specific to you.

It also cannot replace a conversation about what happens if a pregnancy does occur. If this happens, your oncology team, a gynaecologist and often a counsellor will explain the options carefully and without judgement. Some pregnancies can continue with changes to treatment, depending on timing and the cancer, and families are supported whatever they decide.

Emergency contraception

If contraception fails, ask your oncology team or a doctor promptly about emergency contraception that suits your situation. Time matters.

Men on chemotherapy

Men should use condoms with a partner who could become pregnant, even if their sperm count is thought to be low. Damaged sperm may still fertilise an egg.

Same-sex partners and body fluids

Condoms or dental dams help protect partners from traces of medicine, whatever the relationship.

Talking openly

Discussing contraception with a doctor can feel awkward, especially in front of family. It is fine to ask for a private conversation.

Hormone treatment after chemotherapy

People moving on to hormone treatment for breast or prostate cancer may need separate contraception advice.

Young people

Teenagers on treatment also need clear, confidential advice about contraception and sexual health.

Why traces of medicine in body fluids matter

Small amounts of some chemotherapy medicines can be found in semen, vaginal fluids, urine and other body fluids for a short time after each dose, and the length of time varies between medicines. Using condoms during sex in this period protects partners from exposure and helps prevent irritation. It is not a reason to avoid closeness, hugging or sharing a bed. Ask your team how long to use condoms after each treatment, particularly if you take tablets daily at home, where medicine may be present continuously.

Contraception and low blood counts

When blood counts are low, some methods need extra thought. Injections can cause bruising if platelets are low, and fitting a coil carries a small risk of infection or bleeding. Your oncology team may suggest timing a coil fitting for when counts have recovered between cycles, or using condoms until then. If you already have a coil in place, it can usually stay, but tell the team about any unusual pain, discharge or fever.

Periods during treatment

Periods may become lighter, heavier, irregular or stop completely during chemotherapy. Heavy bleeding when platelets are low needs prompt attention. Some women are given medicine to stop periods during treatment to prevent heavy bleeding. None of these changes means contraception can be stopped unless your oncologist says so.

What to do next

Ask your oncologist which method suits you before the first cycle, use condoms throughout treatment, keep your method consistent through every break, report any missed period or contraception failure straight away, and ask how long to continue after your final dose.