Tamoxifen Viatris 20 mg film-coated tablets

Package leaflet: Information for the user

Introduction

Package leaflet: information for the user

Tamoxifeno Viatris 20 mg film-coated tablets

Read the entire leaflet carefully before you start taking this medicine, because it contains important information for you.

• Keep this leaflet. You may need to read it again.
• If you have any questions, ask your doctor or pharmacist.
• This medicine has been prescribed for you only and must not be given to other people, even if they have the same symptoms as you. It could harm them.
• If you experience any adverse reactions, talk to your doctor or pharmacist, even if they are adverse reactions not listed in this leaflet. See section 4.

Contents of the leaflet

1. What Tamoxifeno Viatris is and what it is used for
2. What you need to know before taking Tamoxifeno Viatris
3. How to take Tamoxifeno Viatris
4. Possible adverse effects
5. How to store Tamoxifeno Viatris
6. Contents of the pack and other information

1. What Tamoxifeno Viatris is and what it is used for

Tamoxifeno Viatris contains the active substance called tamoxifeno and belongs to a group of medicines known as antiestrogens.

Estrogen is present in your body and is a natural substance known as a "sex hormone". Tamoxifeno works by blocking the effects of estrogen.

Tamoxifeno Viatris is indicated for certain breast conditions.

2. What you need to know before taking Tamoxifen Viatris

Do not take Tamoxifen Viatris:

• If you are allergic to tamoxifen or to any of the other ingredients of this medicine (listed in section 6).
• If you are pregnant (see “Pregnancy, breast-feeding and fertility”).

Warnings and precautions

Talk to your doctor or pharmacist before starting to take Tamoxifen Viatris.

• Concomitant use with the following medicines should be avoided, as a reduction in the effects of tamoxifen cannot be ruled out: paroxetine, fluoxetine (e.g. antidepressants), bupropion (antidepressant or used to stop smoking), quinidine (used in the treatment of cardiac arrhythmia), and cinacalcet (for the treatment of parathyroid gland disorders).
• If you are using a contraceptive method. Consult your doctor about the contraceptive methods you should use, as some may be affected by this medicine.
• It is important that you inform your doctor immediately if you experience any unusual vaginal bleeding or other gynaecological symptoms (such as pelvic pain or pressure) during treatment with tamoxifen or at any time afterwards. This is because certain changes may occur inside the womb (endometrium), some of which may be serious.
• Before starting treatment with this medicine, it is important that you inform your doctor if you or a family member have a history of blood clots or a known inherited condition that increases the risk of developing blood clots.
• If you are admitted to hospital, inform healthcare staff that you are taking tamoxifen.
• In delayed breast reconstruction surgery (weeks or years after the primary breast surgery, when your own tissue is moved to shape a new breast), tamoxifen may increase the risk of blood clots forming in the small blood vessels of the tissue graft, which could lead to complications.
• This medicine contains tamoxifen, which may produce a positive result in doping control tests.
• Serious skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, have been reported in association with tamoxifen treatment. If you notice any symptoms related to these serious skin reactions described in section 4, stop using tamoxifen and seek medical attention immediately.
• If you have a history of hereditary angioedema, as tamoxifen may trigger or worsen symptoms of hereditary angioedema. If you experience symptoms such as swelling of the face, lips, tongue and/or throat with difficulty swallowing or breathing, contact a doctor immediately.
• Studies in premenopausal women taking tamoxifen to reduce the risk of breast cancer or to treat breast cancer have reported decreases in bone density. If you are a premenopausal woman being treated with tamoxifen, consult your doctor for advice on maintaining bone health.
• If you have any heart disease, including heart rhythm problems (arrhythmias), such as a condition called long QT syndrome (prolongation of the QT interval), the risk of heart rhythm problems may increase if you take tamoxifen.

Children and adolescents

Tamoxifen must not be given to children/adolescents, as its safety and efficacy have not been established in this age group.

Taking Tamoxifen Viatris with other medicines

Tell your doctor or pharmacist if you are taking, have recently taken, or might need to take any other medicines.

You must never take another medicine on your own initiative without your doctor’s recommendation, as some combinations should be avoided.

In particular, you should inform your doctor if you are taking any of the following medicines:

• Warfarin (an oral anticoagulant used to prevent blood clots).
• Rifampicin (for tuberculosis).
• Aromatase inhibitors such as anastrozole, letrozole or exemestane (used to treat breast cancer).
• Paroxetine, fluoxetine (antidepressants).
• Bupropion (antidepressant or used to stop smoking).
• Quinidine (used in the treatment of cardiac arrhythmia).
• Cinacalcet (for the treatment of parathyroid gland disorders).
• Medicines known to affect heart rhythm.

Pregnancy, breast-feeding and fertility

If you are pregnant or breast-feeding, think you may be pregnant or plan to become pregnant, consult your doctor or pharmacist before using this medicine.

Men and women must use an effective method of contraception during treatment with tamoxifen, and women should continue for at least 7 months and men for at least 4 months after stopping treatment.

You must not become pregnant during treatment with tamoxifen or during the two months following discontinuation of treatment.

Do not take tamoxifen if you are breast-feeding, unless your doctor has evaluated the risks and benefits involved. It is not known whether tamoxifen passes into human milk.

Driving and use of machines

The effect of tamoxifen on the ability to drive and use machines is minor.

However, fatigue has been reported with the use of tamoxifen; therefore, caution should be exercised when driving or using machines while these symptoms persist.

Tamoxifen Viatris contains lactose, Orange Yellow S (E-110) and sodium

This medicine contains lactose. If your doctor has informed you that you have an intolerance to certain sugars, consult him/her before taking this medicine.

This medicine may cause allergic reactions because it contains Orange Yellow S (E-110). It may cause asthma, especially in patients allergic to acetylsalicylic acid.

This medicine contains less than 23 mg of sodium (1 mmol) per tablet; this is essentially “sodium-free”.

3. How to take Tamoxifeno Viatris

Follow exactly the instructions for use of this medicine as given by your doctor or pharmacist. If in doubt, consult your doctor or pharmacist again.

Taking Tamoxifeno Viatris

• The recommended dose is 1 tablet (20 mg) to 2 tablets (40 mg) daily.
• Usually, tamoxifeno is taken once or twice a day.
• Swallow the tablets whole with water.
• Try to take the tablet at the same time every day.

Do not stop taking your tablets, even if you feel well, unless your doctor tells you otherwise.

Use in children and adolescents

Tamoxifeno must not be given to children/adolescents, as its safety and efficacy have not been established in this age group.

If you take more Tamoxifeno Viatris than you should

In case of overdose or accidental ingestion, contact your doctor or pharmacist immediately or call the Toxicology Information Service at 91 562 04 20, indicating the medicine and the amount ingested, or go to the nearest hospital emergency department.

If you forget to take Tamoxifeno Viatris

If you forget a dose, take it as soon as you remember. Do not take a double dose to make up for forgotten doses.

If you stop taking Tamoxifeno Viatris

Your doctor will advise you on how long your treatment with tamoxifeno should last. Do not stop treatment before your doctor tells you to.

If you have any further questions about the use of this medicine, ask your doctor or pharmacist.

4. Possible adverse effects

Like all medicines, this medicine can cause adverse effects, although not everyone will experience them.

Stop taking tamoxifen and contact your doctor immediately if you notice any of the following symptoms or adverse effects, as you may require urgent medical treatment:

• Reddish, flat or circular skin rashes on the trunk, often with central blisters, peeling of the skin, and ulcers in the mouth, throat, nose, genitals, and eyes. These severe skin rashes may be preceded by fever and flu-like symptoms (Stevens-Johnson syndrome, toxic epidermal necrolysis); these adverse effects are rare.
• Swelling of the face, lips, tongue, or throat, difficulty swallowing or breathing (angioedema). Tamoxifen may cause or worsen symptoms of hereditary angioedema.

Very common (may affect more than 1 in 10 people):

• Metabolism and nutrition disorders: Fluid retention.
• Vascular disorders: Hot flushes.
• Gastrointestinal disorders: Nausea.
• Skin and subcutaneous tissue disorders: Rash.
• Reproductive system and breast disorders: Vaginal bleeding, vaginal discharge.
• General disorders and administration site conditions: Fatigue.

Common (may affect up to 1 in 10 people):

• Benign, malignant and unspecified neoplasms (incl. cysts and polyps): Uterine fibroids.
• Blood and lymphatic system disorders: Decrease in red blood cells (anaemia).
• Immune system disorders: Hypersensitivity reactions (allergic reactions).
• Nervous system disorders: Sudden onset of weakness or paralysis in arms or legs, sudden difficulty speaking, walking, holding objects, or thinking (any of these may occur due to reduced blood flow to the brain and may be signs of stroke), headache, dizziness, sensory disturbances (including taste disorders and numbness or tingling of the skin).
• Eye disorders: Cataracts, changes in the retina.
• Gastrointestinal disorders: Vomiting, diarrhoea, constipation.
• Hepatobiliary disorders: Changes in liver enzymes, fat accumulation in the liver.
• Skin and subcutaneous tissue disorders: Hair loss.
• Musculoskeletal and connective tissue disorders: Leg cramps, muscle pain.
• Reproductive system and breast disorders: Itching around the vagina, endometrial changes (inside the uterus).
• Investigations: Increased blood fat levels.
• Disorders affecting multiple organs or systems: Increased risk of blood clots (including clots in small vessels).

Uncommon (may affect up to 1 in 100 people):

• Benign, malignant and unspecified neoplasms (incl. cysts and polyps): Tumour in the endometrium (inside the uterus).
• Blood and lymphatic system disorders: Decreased platelet count (thrombocytopenia), decreased white blood cell count (leucopenia).
• Metabolism and nutrition disorders: Increased calcium levels in blood (in patients with bone metastases).
• Eye disorders: Visual disturbances.
• Respiratory, thoracic and mediastinal disorders: Inflammation of lung tissue, which may present symptoms similar to pneumonia, such as difficulty breathing and cough.
• Gastrointestinal disorders: Pancreatitis (pain or tenderness in the upper abdomen).
• Hepatobiliary disorders: Liver cirrhosis (symptoms may include general malaise, with or without yellowing of the skin and eyes), which has occasionally led to death.

Rare (may affect up to 1 in 1,000 people):

• Benign, malignant and unspecified neoplasms (incl. cysts and polyps): Uterine (womb) tumour, symptoms related to your illness.
• Blood and lymphatic system disorders: Decreased neutrophil count (neutropenia), isolated decrease in levels of a specific type of white blood cell (agranulocytosis).
• Nervous system disorders: Optic neuritis and, in a small number of cases, loss of vision (caused by inflammation of the optic nerve).
• Eye disorders: Changes in the cornea, optic nerve disorders and, in a small number of cases, loss of vision (caused by optic nerve disorders).
• Hepatobiliary disorders: Hepatitis, bile flow obstruction, liver failure, liver cell damage (symptoms may include general malaise, with or without yellowing of the skin and eyes), which have occasionally led to death.
• Skin and subcutaneous tissue disorders: Angioedema (swelling of the face, lips, tongue and/or throat), inflammation of small blood vessels in the skin causing a skin rash, severe skin reactions with lesions, ulcers or blisters.
• Reproductive system and breast disorders: Disorders of the inner tissue of the uterus, ovarian cysts, vaginal polyps (non-tumour mass inside the vagina).

Very rare (may affect up to 1 in 10,000 people):

• Skin and subcutaneous tissue disorders: Cutaneous lupus erythematosus (skin inflammation characterized by a rash or redness, mainly in areas exposed to light).
• Congenital, familial and genetic disorders: Skin disorder characterized by blistering due to excessive production of a special group of pigments (called porphyrins) by the liver.

Frequency not known (frequency cannot be estimated from available data):

• Decreased bone mineral density in premenopausal women.
• Changes in the heart's electrical activity (Electrocardiogram showing QT interval prolongation).

If you experience symptoms indicating the formation of a blood clot, such as swelling in the calf or leg, chest pain, shortness of breath, or sudden weakness, STOP taking tamoxifen and contact your doctor immediately.

Reporting of adverse effects

If you experience any adverse effect, talk to your doctor or pharmacist, even if it is a possible adverse effect not listed in this leaflet. You can also report them directly via the Spanish Pharmacovigilance System for Human Medicines: https://www.notificaram.es. By reporting adverse effects, you can help provide more information on the safety of this medicine.

5. Storage of Tamoxifen Viatris

Keep this medicine out of the sight and reach of children.

Do not use this medicine after the expiry date stated on the container after EXP or CAD. The expiry date refers to the last day of the month indicated.

Store in the original packaging to protect from light.

Medicines must not be disposed of via wastewater drains or household waste. Dispose of unused medicines and their containers at the SIGRE collection point at your pharmacy. If you are unsure, ask your pharmacist how to dispose of medicines and containers you no longer need. This will help protect the environment.

6. Contents of the container and other information

Composition of Tamoxifeno Viatris

• The active substance is tamoxifene (as citrate). Each tablet contains 30.34 mg of tamoxifene citrate, equivalent to 20.0 mg of tamoxifene.
• The other components are: corn starch, lactose, povidone (E-1201), orange yellow S (E-110), sodium croscarmellose (E-468), magnesium stearate (E-470b), colloidal silica, talc (E-553b) and hypromellose (E-464).

Appearance of the product and contents of the container

The film-coated tablets are orange, round, biconvex, marked with “20” on the upper face and smooth lower face.

Tamoxifeno Viatris is available in packs of 30 and 60 film-coated tablets, presented in blister packs.

Only certain pack sizes may be marketed.

Marketing Authorization Holder

Viatris Pharmaceuticals, S.L.

C/ General Aranaz, 86

28027 - Madrid

Spain

Manufacturer

Prasfarma, S.L.

C/ Sant Joan, 11-15

08560 - Manlleu, Barcelona

Spain

Date of the most recent review of this package leaflet: March 2026

Detailed information on this medicine is available on the website of the Spanish Agency for Medicines and Health Products (AEMPS) https://www.aemps.gob.es/