A clinical review written from an Australian doctor’s perspective
If you or someone you love has been diagnosed with hormone receptor-positive breast cancer, you already know the fear. The fear of recurrence. The fear of treatment side effects. The fear of losing control over your body, your mood, your weight, and your future. As a doctor, I see this every week in my consulting room. Women over 30 are often juggling work, family, relationships, and now a diagnosis that changes everything.
Many patients tell me they lie awake wondering: “What if the cancer comes back? Will I feel like myself again? Is the treatment worse than the disease?” These are valid questions. But there is one medicine that has been used for decades, has saved millions of lives, and is available on the PBS in Australia. That medicine is tamoxifen.
This article explains why tamoxifen may be one of the most important medicines you ever take — and why you should feel confident asking your doctor about it.
Tamoxifen belongs to a class of medicines called selective oestrogen receptor modulators (SERMs). It works by blocking oestrogen receptors on breast cancer cells. Many breast cancers — called hormone receptor-positive cancers — use oestrogen as fuel to grow and spread. Tamoxifen attaches to the oestrogen receptor instead of oestrogen, starving the cancer cells and slowing or stopping their growth.
But tamoxifen is not simply an “anti-oestrogen” everywhere. It has oestrogen-like effects on some tissues, such as bone and the lining of the uterus, and anti-oestrogen effects on breast tissue. This dual action explains both its benefits and some of its side effects.
In Australia, tamoxifen is listed on the Pharmaceutical Benefits Scheme (PBS) for the treatment of hormone-dependent breast cancer. It is used in both premenopausal and postmenopausal women, and sometimes in men. It is usually taken as a 20 mg tablet once daily, with or without food.
In postmenopausal women, tamoxifen remains an important option. Aromatase inhibitors such as letrozole or anastrozole are often used first in postmenopausal women, but tamoxifen is frequently prescribed when aromatase inhibitors are not tolerated due to joint pain or bone loss, or as part of extended adjuvant therapy. Tamoxifen reduces the risk of breast cancer recurrence, reduces the risk of new breast cancer in the opposite breast, and can help maintain bone density. However, it slightly increases the risk of endometrial cancer and blood clots, so we individualise treatment.
| Question | Doctor’s answer |
|---|---|
| Can tamoxifen cause mood swings? | Yes, some women notice mood swings, irritability, anxiety, low mood, or tearfulness. This is likely due to tamoxifen’s effect on oestrogen receptors in the brain. Not everyone experiences this, but if mood changes are affecting your life, tell your doctor. We can support you with counselling, lifestyle changes, or consider alternative therapy if medically appropriate. Do not stop tamoxifen without medical advice. |
| How does tamoxifen work? | Tamoxifen blocks oestrogen receptors on breast cancer cells, starving hormone-sensitive cancer cells of the oestrogen they need to grow. It is a selective oestrogen receptor modulator, so it has different effects in different tissues. |
| What is the maximum quantity of tamoxifen per PBS script? | Under the PBS, the standard maximum quantity is 60 tablets (20 mg) per prescription — a one-month supply at the usual dose of one tablet daily. Your doctor can prescribe repeats so you do not need a new appointment every month. |
| Do I need regular blood tests on tamoxifen? | For most women, routine blood tests are not required. However, I usually check baseline liver function and full blood count before starting, and then repeat tests only if you have symptoms or risk factors. If you experience abnormal vaginal bleeding, you may need a pelvic ultrasound or endometrial assessment. Your doctor will tailor monitoring to you. |
| Can tamoxifen be imported into Australia? | Under the Therapeutic Goods Administration (TGA) Personal Importation Scheme, it may be possible to import up to a 3-month supply for personal use with a valid Australian prescription. However, I strongly recommend against importing tamoxifen. Australian pharmacies supply TGA-approved tamoxifen through the PBS, ensuring quality, safety, and subsidy. Importing from overseas can expose you to counterfeit or substandard medicines and may not be legal. |
| Can tamoxifen cause weight changes? | Some women report mild weight gain or fluid retention while taking tamoxifen, especially around the waist. It is not universal and may also be related to menopause, cancer treatment, stress, or reduced activity. A balanced diet, regular walking, and strength exercise can help. If weight gain is significant, we can investigate other causes. |
| Can tamoxifen be taken while breastfeeding? | No. Tamoxifen is contraindicated while breastfeeding. It may suppress milk production and pass into breast milk, and the effects on a breastfeeding infant are not safe. If you have recently given birth and need tamoxifen, you should not breastfeed while taking it. Women of childbearing age should use effective non-hormonal contraception while on tamoxifen, as pregnancy is also not recommended during treatment. |
| What is the role of tamoxifen in postmenopausal women? | Tamoxifen is effective in postmenopausal women with hormone receptor-positive breast cancer. It may be used when aromatase inhibitors are unsuitable, as extended therapy after aromatase inhibitors, or in specific risk-reduction settings. It reduces recurrence and new breast cancers while preserving bone density, but requires monitoring for endometrial and clotting risks. |
Imagine finishing your active breast cancer treatment with a sense of security, knowing you are doing something proven to reduce the risk of the cancer coming back. That is what tamoxifen offers millions of women worldwide. It is not a new, experimental drug — it has been used for more than 40 years, has a well-understood safety profile, and is affordable in Australia through the PBS.
You may be worried about side effects like mood swings, weight changes, or blood tests. While some women do experience side effects, many tolerate tamoxifen very well. The important point is that these side effects are manageable and often temporary. If you experience mood changes, we can refer you to a psychologist. If you experience weight changes, we can involve a dietitian or exercise physiologist. If you have questions about monitoring, we can create a simple plan that fits your life. You are not alone in this.
For Australian women, tamoxifen is accessible. You do not need to import it from overseas. You can walk into any Australian pharmacy with a PBS prescription and receive a high-quality, TGA-approved medicine at a subsidised price. That means you can focus on your recovery, not on sourcing medicine.
Most importantly, tamoxifen gives you something priceless: a lower risk of breast cancer recurrence and a better chance of long-term survival. For postmenopausal women, it can be a lifeline when other hormonal therapies are not suitable. For premenopausal women, it remains a cornerstone of treatment. If you are over 30 and have been diagnosed with hormone receptor-positive breast cancer — or are at high risk — tamoxifen may be one of the best decisions you make.
Do not let fear or uncertainty stop you from getting the treatment you deserve. Here is what I recommend you do right now:
Tamoxifen is not just a pill. It is a daily act of protection against breast cancer recurrence. As a doctor, I have seen it give women their future back. If you are eligible, do not hesitate — ask your doctor about tamoxifen today, and take the next confident step toward protecting your life.
Disclaimer: This article is for educational purposes only and does not replace individual medical advice. Speak with your doctor before starting or changing any medication.
