Norethisterone injection is given to prevent pregnancy. It provides contraception for about eight weeks.
Read the manufacturer's information leaflet from the pack before having the injection.
The most common side-effect is irregular menstrual bleeding.
About norethisterone contraceptive injection
|Type of medicine||Progestogen|
|Also called||Norethindrone (in US); Noristerat®|
Norethisterone is a progestogen, which is a female sex hormone similar to the progesterone hormone made naturally by your ovaries. It is an effective and convenient form of short-term contraception. The injection will provide contraception for about eight weeks.
Norethisterone works mainly by stopping ovulation (the release of an egg from the ovary). It also changes the lining of your womb (uterus) to make it less likely that an egg would attach to it, even if an egg were to fertilise. In addition, the mucus which forms a plug in the neck of your womb (cervix) becomes thicker. This stops sperm getting through to the womb to fertilise an egg.
Before you have norethisterone contraceptive injection
Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before having Noristerat® it is important that your doctor knows:
- If you think you could already be pregnant.
- If you have any problems with the way your liver works.
- If you have a problem with your arteries, called arterial disease.
- If you have an ovarian cyst, or any vaginal bleeding other than your normal monthly period.
- If you have systemic lupus erythematosus (this is an inflammatory condition, often called SLE).
- If you have ever had an ectopic pregnancy or if you have developed severe itching of your skin, or yellowing of your skin or the whites of your eyes (jaundice) during a pregnancy.
- If you have had breast cancer or a cancer that you have been told is dependent on a sex hormone.
- If you have ever had depression.
- If you have a rare inherited blood disorder called porphyria.
- If you have ever had an allergic reaction to a medicine.
- If you are taking any other medicines, including those available to buy without a prescription, as well as herbal and complementary medicines. This is because some medicines interfere with the way progestogen contraceptives work.
How norethisterone contraceptive injection is given
- Before you are given the injection you will be asked to read a printed information leaflet from the manufacturer. The manufacturer's leaflet will give you important information about the injection and will provide a full list of the side-effects which you may experience from it. If you have any questions as a result of reading the leaflet, please discuss them with your doctor/nurse before you have the injection. You will be given the leaflet to take home.
- You will be given the injection by your nurse or doctor. It is usually given during the first 1-5 days of a period. The norethisterone is injected slowly into a muscle in your buttock. From there, it is gradually released into your bloodstream.
Getting the most from your treatment
- Your periods are likely to change. Spotting, breakthrough bleeding and delayed periods may occur. Some women have irregular bleeding which can be heavier and longer than normal. Irregular bleeding can sometimes also be due to another reason (such as an infection), so let your doctor know if it happens.
- Norethisterone injection provides contraception for eight weeks. It is often given as an interim measure - for example, while your partner is having a vasectomy. Make sure your doctor knows if there is any delay to your longer-term plans for contraception.
- You may gain a little weight. Eating a well-balanced diet and taking regular exercise can help to keep this to a minimum.
- Regularly check your breasts for any lumps or bumps. Speak with your doctor if you notice any changes.
- Please note: the injection will not protect you against HIV (AIDS) or any other sexually transmitted infections.
- Some medicines can reduce the effectiveness of this contraceptive. These include medicines for epilepsy, medicines to treat fungal infections, the herbal preparation St John's wort, and medicines used to treat tuberculosis (TB). Tell the doctor that you have had a progestogen contraceptive injection if you are prescribed any other medicines. If you buy any medicines 'over the counter', ask the pharmacist for advice.
Can norethisterone contraceptive injection cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with a norethisterone contraceptive injection. You will find a full list in the manufacturer's information leaflet that has been given to you. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Very common Noristerat® side-effects (these affect more than 1 in 10 women)||What can I do if I experience this?|
|Spotting||If you are concerned, speak with your doctor|
|Irregular periods||Let your doctor know if this happens|
|Common Noristerat® side-effects (these affect less than 1 in 10 women)||What can I do if I experience this?|
|Headache||Ask your pharmacist to recommend a suitable painkiller|
|Feeling sick (nausea)||This does not usually last for long but in the meantime, stick to simple meals|
|Increased weight, skin reactions, feeling dizzy||If troublesome, speak with your doctor|
If you experience any other symptoms which you think may be due to the injection, speak with your doctor or pharmacist for advice.
Important information about all medicines
If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking or using.
Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about your medicines, ask your pharmacist.
Further reading and references
Manufacturer's PIL, Noristerat® 200 mg solution for intramuscular injection; Bayer plc, The electronic Medicines Compendium. Dated June 2019.
British National Formulary, 78th Edition (Sep 2019); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.