Norimin Tablets

Norimin is a combined oral contraceptive tablet containing norethisterone 1 milligram and ethinylestradiol 35 micrograms per tablet. It is licensed in the United Kingdom for the prevention of pregnancy. Norimin belongs to the combined hormonal contraceptive group of medicines and works by preventing ovulation, thickening cervical mucus, and altering the uterine lining. It is taken as one tablet daily for 21 days followed by a seven-day break. Manufactured by Pfizer Limited, Norimin is a Prescription Only Medicine requiring a clinical consultation before it can be dispensed.

Norimin is a monophasic combined oral contraceptive, which means every tablet in the 21-tablet pack contains the same hormone dose throughout the course. There are no colour changes, no phase steps, and no variation in what you are taking from day one to day 21.

Each tablet contains two active hormones. Norethisterone 1 milligram is the progestogen component. Ethinylestradiol 35 micrograms is the synthetic oestrogen. Together they suppress ovulation through the same hormonal pathway used by all combined pills, while also working on the cervix and uterine lining to add further layers of contraceptive protection.

Norethisterone belongs to the first generation of synthetic progestogens. It has a longer clinical track record in UK prescribing than third-generation alternatives such as desogestrel or gestodene, and its safety profile is well documented across decades of use. One characteristic specific to first-generation progestogens is mild androgenic activity – a weak interaction with androgen receptors in addition to progesterone receptors. At 1 mg this effect is present but modest. Most women will not notice it, though those with androgen-sensitive skin may experience oiliness or acne in a small number of cases.

Norimin sits alongside Brevinor within the norethisterone combined pill family. Both use ethinylestradiol 35 micrograms. The difference is the norethisterone dose: Norimin delivers 1 milligram per tablet, which is twice the 500 micrograms in Brevinor. This higher dose gives Norimin a stronger progestogenic effect, which in some women produces better cycle control and fewer episodes of breakthrough spotting.

Norimin uses three biological mechanisms to prevent pregnancy, each targeting a different stage of the reproductive process.

Stopping Ovulation

The principal action is ovulation suppression. Ethinylestradiol and norethisterone combine to inhibit the pituitary hormones that govern the menstrual cycle. Follicle-stimulating hormone and luteinising hormone are both reduced. Without the luteinising hormone surge that acts as the trigger for egg release, the ovary remains inactive. No egg is released, and fertilisation cannot take place. This is the primary and most reliable mechanism.

Thickening Cervical Mucus

Norethisterone alters the consistency of cervical mucus throughout the active phase. The mucus becomes thicker and far less permeable to sperm. Even in an uncommon cycle where ovulation suppression is not fully achieved, this physical barrier makes fertilisation substantially less likely. The mucus effect is active from the earliest days of the pack and is closely linked to consistent daily timing – taking Norimin at around the same time each day helps maintain this protective environment.

Changing the Uterine Lining

The combined hormonal environment produced by Norimin transforms the endometrium into a form that is less receptive to a fertilised egg. This third mechanism adds a final layer of protection that operates independently of the first two. In practice, the combination of reliable ovulation suppression and cervical mucus thickening means this third step is rarely the deciding factor.

The Withdrawal Bleed

When you stop taking active tablets after day 21, oestrogen and norethisterone levels fall. This controlled hormone withdrawal causes the endometrium to shed, producing a withdrawal bleed during the seven-day break. This bleed is driven by the change in hormones rather than by a natural menstrual cycle. It is typically lighter and more predictable than a period, and usually starts within two to three days of the last active tablet. Starting the next pack on day 29 re-establishes hormonal suppression without giving the ovaries time to become active.

Starting Your First Pack

Starting on day one of your period gives you immediate protection. If you begin between days two and five, use condoms for your first seven days on Norimin.

Switching from another combined pill: take your first Norimin tablet the day after your last active tablet from the previous pack. If your previous pill included inactive placebo tablets, start Norimin the day after the last placebo. You are protected straight away.

Switching from a progestogen-only pill: start on any day and use a barrier method for the first seven days.

Your Daily Routine

Take one tablet at the same time every day for 21 consecutive days. After day 21, stop completely for seven days, then start a new pack on day 29 whether or not the withdrawal bleed has finished. That seven-day pause must not stretch beyond seven days. Even a slightly extended break can allow the ovaries to begin follicle development before the new pack restores hormonal suppression.

1. Swallow each tablet whole with a glass of water.
2. Taking Norimin at the same time each day helps maintain a steady hormonal environment.
3. If you vomit within two hours of taking a tablet or have severe diarrhoea, the dose may not have been fully absorbed. Treat it as a missed tablet.

Missed Tablets

Under 24 hours late: take it as soon as you remember and carry on with the pack. Your protection remains intact.

More than 24 hours late: take the missed tablet now and take the next one at the usual time, even if this means two tablets in one day. Use a barrier method for the following seven days.

Two or more tablets missed consecutively: take only the most recently missed tablet, leave the others, and continue the pack. Use condoms for seven days. If those missed tablets fell in week one of the pack and you had unprotected sex during that window, speak to your prescriber or pharmacist about emergency contraception without delay.

Norimin is available in one strength: norethisterone 1 milligram and ethinylestradiol 35 micrograms per tablet. The pack contains 21 identical active tablets. One tablet is taken daily for 21 days, followed by a seven-day break, then a new pack starting on day 29.

How Norimin Compares to Brevinor

Both Norimin and Brevinor are norethisterone-based combined pills manufactured by Pfizer Limited. Both use ethinylestradiol 35 micrograms. The norethisterone dose is the only clinical difference between them:

1. Norimin: norethisterone 1 milligram per tablet
2. Brevinor: norethisterone 500 micrograms per tablet

Prescribers may consider Norimin for women who have experienced irregular bleeding or poor cycle control on the lower-dose Brevinor. The reverse switch, from Norimin to Brevinor, may be appropriate when reducing progestogenic or androgenic side effects is the clinical priority. Both are available through Pharmacy Planet; your prescriber determines which is appropriate for your circumstances based on your health history and previous pill experience.

Generic Availability

Norimin does not have a widely available generic equivalent in the current UK market in the same way that levonorgestrel-based pills such as Microgynon 30 do. If your pharmacy cannot supply Norimin, they will need to source it specifically. Contact your prescriber if supply becomes a persistent issue, as they may need to consider a clinically comparable alternative.

The information below reflects the current UK SmPC for Norimin. Side effects vary between individuals. Many women take Norimin without significant problems. Read the Patient Information Leaflet in full before you begin.

Common Side Effects

Headache, nausea, breast tenderness, mood changes, and altered libido are among the most frequently reported effects across combined pills, including Norimin. Changes to the withdrawal bleed pattern, particularly spotting in the first one to three cycles, are also common and usually resolve as the body adjusts.

Because norethisterone has mild androgenic activity, a minority of women may notice acne or oily skin, particularly those who have experienced these effects on norethisterone preparations before. This is more likely to be relevant for some women at the 1 mg dose in Norimin than at the 500 mcg dose in Brevinor.

Less Common Side Effects

1. Weight changes
2. Contact lens intolerance due to changes in corneal curvature
3. Chloasma: skin darkening on the face, worsened by sun exposure
4. Changes in vaginal discharge

Serious Side Effects Requiring Urgent Attention

Stop taking Norimin and seek immediate medical help if you notice any of the following:

1. Sudden chest pain, breathlessness, or coughing up blood
2. Swelling, pain, heat, or redness in one leg
3. A sudden severe headache, loss of vision, difficulty speaking, or weakness on one side of the body
4. Severe sudden abdominal pain
5. Yellowing of the skin or the whites of your eyes

These may indicate a blood clot, stroke, or liver problem.

Blood Clot Risk

All combined pills carry a small increased risk of venous thromboembolism compared with not using hormonal contraception. Norethisterone-containing combined pills including Norimin sit in the same general VTE risk category as levonorgestrel-based preparations – lower than the risk associated with third-generation progestogen pills such as those containing desogestrel or gestodene. This is confirmed in MHRA guidance. Your prescriber evaluates your individual risk profile before any prescribing decision is made.

Drug Interactions

Medicines that speed up liver enzyme activity reduce the circulating levels of both ethinylestradiol and norethisterone, which can compromise contraceptive effectiveness. These include rifampicin and rifabutin, several antiepileptic medicines including phenytoin, carbamazepine, phenobarbital, and topiramate, some HIV antiretrovirals, and St John's Wort. Tell your prescriber about every medicine, supplement, and herbal product you take at every consultation.

Norimin Is Not Suitable If You:

1. Have ever had a blood clot – DVT, pulmonary embolism, stroke, or heart attack
2. Experience migraine with aura: an absolute contraindication to all oestrogen-containing combined pills
3. Have uncontrolled high blood pressure
4. Have active or past liver disease, liver tumours, or jaundice caused by previous pill use
5. Have a current or previous diagnosis of breast cancer or any oestrogen-sensitive malignancy
6. Are pregnant
7. Are breastfeeding a baby under six weeks old
8. Smoke and are 35 or older
9. Have diabetes affecting your blood vessels

Norimin May Be Appropriate If You:

1. Are a healthy adult woman with no contraindications to oestrogen-containing contraception
2. Have experienced inadequate cycle control or breakthrough bleeding on a lower norethisterone dose such as Brevinor, and a prescriber has assessed that a higher progestogen dose is appropriate
3. Have no personal or family history indicating elevated clotting risk
4. Have no history of androgenic side effects on norethisterone-containing preparations, or your prescriber has assessed this as manageable

Discuss With Your Prescriber First If You:

1. Smoke and are under 35
2. Have a BMI above 30
3. Have a first-degree family member who had a blood clot before the age of 50
4. Have any form of migraine, including without aura
5. Are planning long-haul travel or a period of extended immobility
6. Have previously experienced acne or oily skin on norethisterone-containing combined pills
7. Have a history of depression or are currently receiving treatment for a mood disorder

Pharmacy Planet is a GPhC registered UK online pharmacy. Every Norimin prescription is issued following a clinical consultation reviewed individually by a registered prescriber. The consultation is the first step in the process. A prescription is one possible outcome, not a guaranteed result.

Because Norimin delivers a higher norethisterone dose than Brevinor, the prescriber's assessment considers your previous pill history and tolerability alongside the standard combined pill checklist. If you have moved between norethisterone preparations before, your experience will inform the prescriber's judgement about whether Norimin is the right choice at this point.

The outcome may be a prescription for Norimin, a recommendation to use Brevinor or a different progestogen class, a request for more information, or a referral for an in-person review. Repeat prescriptions follow the same individual review. There is no automatic renewal at Pharmacy Planet.

Store Norimin below 25°C, away from direct sunlight, damp, and heat sources. A bathroom cabinet is generally not an ideal storage location due to humidity from showers. A bedside table or a dry kitchen cupboard away from the hob tends to work better for maintaining consistent conditions.

Keep tablets in the original blister strip until you take them. The foil protects from moisture and the day markings help you track where you are in the pack. Store all medicines out of the sight and reach of children.

Check the expiry date on the outer carton before each new pack. Return any unused or out-of-date tablets to a UK pharmacy for safe disposal. Pharmacies accept returned medicines at no charge. Do not flush tablets down the toilet or put them in household waste.

This reference guide compares the contraceptive preparations available at Pharmacy Planet, grouped by delivery method and formulation type. Every preparation is a Prescription Only Medicine. A registered prescriber will review your individual health profile, contraceptive history, and risk factors before recommending any preparation. This table is a clinical reference, not a recommendation.

Combined Oral Contraceptive Tablets (Monophasic)

Monophasic combined pills contain the same dose of both hormones in every active tablet. The table below compares commonly prescribed monophasic combined oral contraceptives by progestogen type, oestrogen dose, VTE risk category, pack format, and key clinical characteristics.

Important: This comparison is for general information only and does not replace medical advice. A prescriber will decide which treatment is suitable for you following an online consultation.

Deciding between Norimin and Brevinor, or between a norethisterone-based pill and one using a different progestogen class, is not a decision that should rest on patient preference alone. The norethisterone dose, its mild androgenic activity, the individual woman's history of tolerability, and her VTE risk profile all need to be considered by a clinician who has read the details. At Pharmacy Planet, every Norimin consultation is reviewed by a registered prescriber who takes that clinical responsibility seriously before any prescribing decision is made.

If Norimin is not the most appropriate preparation for your circumstances, the prescriber will say so and explain what might serve you better. That is part of the clinical process, not a failure of it.

• Pfizer Limited. Norimin film-coated tablets – Summary of Product Characteristics. Available at: www.medicines.org.uk/emc. Accessed May 2026.
• Faculty of Sexual and Reproductive Healthcare (FSRH). Combined Hormonal Contraception – Clinical Guidance. Available at: www.fsrh.org. Accessed May 2026.
• NHS. Combined pill – your contraception guide. Available at: www.nhs.uk/conditions/contraception/combined-contraceptive-pill. Accessed May 2026.
• British National Formulary (BNF). Ethinylestradiol with norethisterone. Available at: bnf.nice.org.uk. Accessed May 2026.
• MHRA. Combined hormonal contraceptives and venous thromboembolism – updated guidance. Available at: www.gov.uk/government/organisations/medicines-and-healthcare-products-regulatory-agency. Accessed May 2026.