Please note - we no longer offer Micronor. But we can recommend Noriday as an alternative with the same active ingredient.

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from £14.99

Product details

Micronor is a mini pill, or progesterone-only pill, which means that it only contains one hormone. Micronor contains norethisterone, a synthetic version of the naturally occurring sex hormone progesterone. Micronor is only available with a doctor’s prescription.

Dr Simran Deo Medical Editor

Medically reviewed by

Dr Simran Deo

Last reviewed: 09 Jul 2020

Noriday Prices

Pack Size Price
350 mcg - 3 x 28 tablet(s) £14.99
350 mcg - 6 x 28 tablet(s) £19.99

How it Works

About Micronor


How effective is Micronor?

Like other minipills, Micronor is 99% effective at preventing pregnancy when taken correctly. It works by thickening the mucus at the entrance to the womb, which makes it harder for sperm to get to an egg. It also alters the lining of the womb, so that any fertilized eggs cannot implant and develop.

How is Micronor taken?

Micronor is very effective at preventing unwanted pregnancies, but it needs to be taken at the same time everyday to work properly. Unlike combined pills, which allow for a slightly more flexible schedule, Micronor can fail to work if it is taken more than three hours late. This is due to the fact that it is a progesterone-only pill, which contains a low dose of hormones. It is taken on a daily basis, without a break. It is very important that you stick to a daily routine of taking your mini pill at the same time. Be particularly careful when travelling across time zones, to make sure you do not risk falling pregnant.

What happens if I forget to take my pill?

If you do forget to take your pill and more than three hours have passed since the time that it was due, you need to take it as soon as you remember. The next dose must follow at your usual time, even if this means that you are taking two Micronor pills on the same day. You will also need to use an additional method of contraception for two days. If you have had sex in the two days before you missed a pill, you could get pregnant. You should speak to a doctor for advice on whether you need emergency contraception.

What do I need to do if I vomit?

If you vomit or have severe diarrhoea within three hours of taking Micronor, you will have to take an additional dose to make sure that you are protected from pregnancy. If you suffer from ongoing problems with your digestion, you may need to consider an alternative form of contraception.

What if I miss a period on Micronor?

It is not unusual for periods to be lighter and less painful when taking a contraceptive pill. Many women regard this as a positive side effect of Micronor. If you have taken your pills as advised it is highly unlikely that you are pregnant. However, if you miss another period, or if you are really worried, you could take a pregnancy test to confirm that your contraception was successful. Many women experience bleeding and spotting in between periods. This is a very common side effect, not only of Micronor but of most progesterone-only pills. If you experience very heavy or ongoing bleeding whilst you’re taking your pill, see a doctor as soon as you can.

Can I take Micronor while breastfeeding?

Due to its low hormone levels, Micronor can be taken by breastfeeding women. Oestrogen-free pills are also often recommended to women who smoke, are obese or are otherwise at risk of thrombosis (blood clots). Please note that our service is for repeat prescriptions only.


What is in Micronor?

Micronor contains norethisterone. This is a synthetic version of the naturally occurring sex hormone progesterone. Each tablet contains 350 micrograms of norethisterone and this is the ‘active ingredient’ in the medication. Each Micronor tablet also contains magnesium stearate, pre-gelatinised starch and lactose.

Micronor side effects

A very common side effect of Micronor is bleeding and spotting between periods. More than one in ten women experience this side effect during treatment with Micronor.

Common Side Effects:

  • dizziness
  • headache
  • nausea and vomiting
  • breast tenderness
  • tiredness
  • missed periods

Uncommon Side Effects:

  • depression
  • anxiety
  • skin problems (such as acne and rash)
  • stomach problems
  • hair loss and excessive hair growth
  • leg pain
  • period pain
  • heavy bleeding
  • itchy rash
  • vaginal discharge
  • hypersensitivity
  • ovarian cyst
  • breast pain

Bleeding and spotting

Bleeding and spotting between periods are a very common side effect with Micronor, which means that more than 1 in 10 women who use Micronor will experience this side effect at some point during their treatment. Irregular bleeding is particularly common during the first three months of treatment and will usually subside once your body has adjusted to the hormones in Micronor. Spotting is mild and should stop after a couple of days. If you experience severe bleeding you should see a doctor without delay.

Drug interactions

Micronor is known to interact with the following medicines:

  • aprepitant and fosaprepitant (drugs used in chemotherapy)
  • anti-HIV medicines
  • barbiturates (regularly prescribed for anxiety, depression and insomnia)
  • St. John’s Wort
  • rifampicin and rifabutin (used to treat tuberculosis)
  • griseofulvin (prescribed to treat fungal infections)
  • bosentan (used to treat pulmonary arterial hypertension - or high blood pressure in the blood vessels that supply the lungs)
  • some epilepsy treatments (for example carbamazepine and phenytoin)

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