Side effects of Utovlan (Norethisterone)

What is Norethisterone and what is it used for?

Norethisterone, sold under the brand name Utovlan, is a progesterone medicine that works by mimicking the naturally produced hormone progesterone. It prevents the lining of the womb from shedding, which delays your period.

Norethisterone is the only progesterone pill licensed in the UK specifically for period delay. It is also prescribed for heavy periods, painful periods, irregular periods, premenstrual syndrome (PMS), and endometriosis.

It is important to know that norethisterone at the dose used for period delay is not a contraceptive. It will not protect you from pregnancy. If there is any chance you could become pregnant, you should use additional contraception such as a condom while taking it.

Is Norethisterone safe?

Norethisterone is considered safe when used as prescribed for its intended purposes. It has been used clinically for decades and is well understood by pharmacists and doctors.

It is not suitable for everyone. It should not be used during pregnancy or by anyone with a history of blood clots, liver disease, or hormone-sensitive cancers. You should always complete a clinical consultation before starting treatment so that a clinician can confirm it is appropriate for you.

Norethisterone side effects

Like all medicines, norethisterone can cause side effects, though not everyone will experience them.

Very common side effects (affecting more than 1 in 10 people):

• Vaginal spotting (If bleeding continues for more than a week, speak to one of our clinicians)
• Shorter or lighter periods than usual

Common side effects (affecting up to 1 in 10 people):

• Headaches
• Nausea
• Absent periods (amenorrhoea)
• Swelling or fluid retention in the hands or ankles

These are usually mild and often improve as your body adjusts to the medication. Taking norethisterone with food can help reduce nausea.

Less common side effects (affecting up to 1 in 100 people):

• Migraines
• Breast tenderness or pain, and skin reactions such as rash or hives.

Rare side effects (affecting up to 1 in 1,000 people):

• Allergic reactions including hives or skin rash.

If you experience your first ever migraine while taking norethisterone, or a migraine that is worse than any you have had before, stop taking the medication and seek medical advice immediately.

Very rare:

• Visual disturbances
• Dizziness
• Abdominal pain
• Worsening of depression
• Jaundice (yellowing of the skin and eyes)
• Cholestasis

Serious side effects: when to stop taking norethisterone immediately

Serious side effects are rare but important to know about. Because norethisterone is partly converted into oestrogen in the body, the guidance around serious risks is similar to that for the combined contraceptive pill.

Stop taking norethisterone and seek immediate medical help if you notice any of the following, as these can be signs of a blood clot:

• Pain
• Swelling
• Redness in one leg
• Sharp or crushing pain in your chest
• Sudden shortness of breath or coughing for no obvious reason
• One side of your body suddenly becoming numb or very weak
• Sudden changes to your vision, hearing, speech, smell, taste, or sense of touch
• A migraine for the first time, or one that is worse than normal
• Yellowing of the skin or whites of the eyes (jaundice)

Your risk of a blood clot is slightly higher if you:

• Smoke

If you have had breast cancer, or have it currently, you should not take norethisterone. Like the combined contraceptive pill, it can slightly increase the risk of breast cancer, and this risk rises with longer use.

The risk returns to normal within around 10 years of stopping. See your GP as soon as possible if you notice any changes in your breasts such as lumps, skin dimpling, or nipple changes.

How long do norethisterone side effects last?

Most side effects are temporary and will clear up once you stop taking norethisterone:

Bleeding and spotting: Usually settles within a few days. If it persists or is heavy, speak to our clinical team.

Headaches and nausea: These tend to appear early in treatment and often improve within a few days to a couple of weeks as your body adjusts.

Mood changes and breast tenderness: These can last for the duration of treatment for some people but may ease over time.

Serious side effects such as blood clots do not resolve on their own and require immediate medical attention.

How long should you take norethisterone?

For period delay, norethisterone should not be taken for longer than 17 days. You start taking it three days before your period is expected and it can delay your period by up to 17 days.

Using norethisterone frequently over long periods is not recommended without medical supervision, as it can increase your risk of side effects.

If you need to use it for longer than 17 days, speak to your doctor.

Long-term side effects of norethisterone

Norethisterone is not typically taken long-term. However, it is sometimes prescribed for conditions like endometriosis for six months or more. If you are on a longer course, be aware of the following:

Cardiovascular health: There is a small increased risk of blood clots with long-term progesterone use, particularly when combined with other risk factors such as smoking or obesity.

Bone health: Some hormonal treatments have been associated with reduced bone density over time. If you are on a long course, your doctor may recommend calcium and vitamin D supplementation.

Hormonal effects: Long-term use can cause changes to your menstrual cycle, libido, or mood.

Liver function: Norethisterone is not suitable for people with certain liver conditions and may, in rare cases, affect liver enzymes. Your doctor may recommend periodic monitoring.

Cancer risk: There is some evidence of a slight increase in the risk of hormone-related cancers such as breast cancer with long-term use. Regular breast checks and open conversation with your GP are important.

Mood and wellbeing: Some people experience persistent mood changes with prolonged use. If this affects you, speak to our team or your GP.

Side effects after stopping norethisterone

When you stop taking norethisterone, your hormone levels drop and your body returns to its natural cycle. This hormonal shift can cause temporary effects that you should be aware of:

Withdrawal bleeding: This is the most common effect. Your period should arrive within two to three days of stopping norethisterone. It may feel slightly different to your usual period, either heavier, lighter, or shorter.

If your period does not arrive within a few days of stopping, take a pregnancy test, as norethisterone is not a contraceptive.

Mood changes: Some people notice a brief dip in mood or feel irritable or emotional for a few days after stopping. This is caused by changing hormone levels and usually passes quickly.

Breast tenderness: May occur temporarily as oestrogen and progesterone levels readjust.

Headaches: Hormonal headaches can occur when hormone levels change. Staying hydrated and resting can help.

Bloating and digestive changes: Mild bloating or abdominal discomfort may occur temporarily.

Irregular cycles: Your next one or two cycles may be slightly different in length or flow. This is normal and usually settles without any treatment.

Acne or skin changes: Hormonal fluctuations can trigger temporary mild breakouts in people who are sensitive to hormone changes.

These effects are usually short-lived.

If bleeding is very heavy and does not improve, or if you experience severe abdominal pain, persistent mood changes, or symptoms that go on longer than expected, seek medical advice.

Does norethisterone affect fertility?

No. There is no evidence that norethisterone affects long-term fertility. Once you stop taking it, ovulation resumes and your fertility returns to normal. Research has found no impairment of fertility in women who have used norethisterone.

If you are trying to conceive, stop taking norethisterone first and speak to your GP or prescriber if you have any concerns.

Does norethisterone cause weight gain?

Weight gain is listed as a possible side effect of norethisterone, though not everyone experiences it.

Research suggests that any weight gain associated with norethisterone may be linked to hormonally induced water retention rather than increases in body fat.

An average weight gain of around 1.6 kg has been reported in studies. For most people, this is temporary and resolves after stopping the medication.

Does norethisterone reset your cycle?

Norethisterone does not reset your cycle, but it can shift its timing. Because your period arrives two to three days after stopping norethisterone, the date of your next period and the cycle that follows may be slightly different to your usual pattern.

For most people, things return to normal within one to two cycles.

Are there alternatives to norethisterone for period delay?

Yes. Medroxyprogesterone (commonly known by the brand name Provera) is another option. It may be more suitable for people who are sensitive to oestrogen, as norethisterone is partly converted into oestrogen in the body. The combined contraceptive pill can also be used to manage period timing. Speak to our clinicians or your GP about which option is most appropriate for you.

How to reduce the side effects of norethisterone

• Take it with food, particularly if you feel nauseous – a light snack before your tablet can make a real difference.
• Take it at the same time each day to maintain stable hormone levels.
• Stay well hydrated and eat a balanced diet – avoiding excessive salt can help reduce fluid retention.

• Limit alcohol – it can make symptoms like headaches, nausea, and fatigue worse.

• Avoid smoking – smoking increases the risk of blood clots when taking hormonal medication.
• Manage stress where possible – stress can worsen mood-related side effects.
• Track your symptoms – if side effects are affecting your daily life or do not settle, speak to our clinical team. There may be an alternative treatment that suits you better.

When to speak to a clinician

Contact your GP if any of the following apply:

• You experience bleeding that continues for more than a week or becomes very heavy. You have a migraine for the first time while taking norethisterone.
• Side effects are affecting your daily life or are not improving.
• You suspect a blood clot (seek emergency help immediately in this case).
• Your period does not return within a few days of stopping norethisterone.