Norethisterone Side Effects: What to Expect

Norethisterone is the medicine most commonly used to delay a period for a holiday, wedding or event. It’s effective and, for most healthy people, well tolerated — but like any medicine it can cause side effects. This guide explains what to expect, who should avoid it and how to use it safely.

What is norethisterone?

Norethisterone is a progestogen, a synthetic form of the natural hormone progesterone. It has several medical uses, but it’s best known for delaying menstruation. Your period begins when the level of progesterone in your body drops, which triggers the lining of the womb to shed. By taking norethisterone, you keep progesterone levels artificially high, so the womb lining is maintained and your period is postponed. When you stop taking the tablets, hormone levels fall and your period usually arrives within two to three days. Because it’s a prescription-only medicine, norethisterone must be supplied after a consultation with a prescriber, who checks it’s safe and suitable for you. Used occasionally and as directed, it’s a simple way to take control of your cycle around an important date — and most people experience few or no problems.

How norethisterone is taken for period delay

For period delay, norethisterone is usually started three days before your period is due and taken three times a day until you no longer wish to delay, up to a maximum of around 17 days. Your prescriber will give you an exact schedule. Starting on time matters — if you begin too late, bleeding may already have started.

Common side effects

Most side effects are mild and temporary. The ones people report most often include:

• Nausea — usually mild; taking tablets with food can help
• Bloating or fluid retention
• Breast tenderness
• Headache
• Mood changes — feeling more irritable or low
• Light spotting or breakthrough bleeding in some people

These effects typically ease once you finish the course and your hormones return to their normal pattern.

Less common and serious effects

More serious side effects are uncommon with short-term use, but it’s important to be aware of them. Progestogens carry a small increased risk of blood clots. Seek urgent medical advice if you experience:

• Pain, swelling or redness in a leg
• Sudden breathlessness or chest pain
• Coughing up blood
• A sudden severe headache, or weakness on one side of the body
• Yellowing of the skin or eyes (jaundice)

These are rare, but knowing the warning signs means you can act quickly if needed.

Who should not take norethisterone?

Norethisterone isn’t suitable for everyone. It’s generally avoided if you:

• Have a history of blood clots (deep vein thrombosis or pulmonary embolism)
• Have certain heart or circulatory conditions
• Have particular liver problems or a history of certain cancers
• Are pregnant or think you might be

This is exactly why a prescriber reviews your medical history before supplying it. If norethisterone isn’t right for you, there may be safer alternatives to discuss.

Does norethisterone affect contraception or fertility?

The doses used for period delay are not a reliable contraceptive, so don’t depend on norethisterone to prevent pregnancy. It doesn’t affect your long-term fertility — your normal cycle resumes after you stop. If you already use hormonal contraception, there may be other ways to manage bleeding around an event; mention this in your consultation.

Using norethisterone safely

To get the best results with the fewest problems:

• Start at the right time — three days before your period is due
• Take it exactly as prescribed and don’t exceed the recommended duration
• Take tablets with food if nausea is an issue
• Be honest about your medical history during your consultation
• Know the warning signs of serious effects and seek help if they occur

If you’d like to delay your period for an upcoming occasion, you can arrange a confidential consultation and order period delay tablets online with next-day delivery, or visit our Sheffield clinic in person. For more on timing and safety, see our guide on how to delay your period safely.