Can I take Anastrozole and Venlafaxine together?

Why this happens

Anastrozole is an aromatase inhibitor used to treat breast cancer, and venlafaxine is an antidepressant (SNRI). They are processed by different pathways in the liver and do not interfere with each other's effectiveness or increase the risk of side effects. Unlike some other antidepressants (such as fluoxetine or paroxetine), venlafaxine does not block the enzymes needed for breast cancer treatments to work.

What you should do

You can continue taking both medications as prescribed. However, always inform your doctor or pharmacist if you notice any new or worsening side effects, such as increased hot flushes, nausea, or changes in mood.

Important precautions

Mental health and mood disorders

Venlafaxine can cause an increase in suicidal thoughts or self-harm, particularly when first starting treatment or changing doses. Monitor your mood closely and seek urgent medical help if you notice any distressing changes.

Pregnancy and Pre-menopause

Anastrozole must only be taken by women who have reached menopause. It can cause severe harm to an unborn baby and is strictly contraindicated if you are pregnant or could still become pregnant.

Serotonin Syndrome risk

Do not take venlafaxine if you have taken a Monoamine Oxidase Inhibitor (MAOI) antidepressant in the last 14 days. Combining these can cause a life-threatening reaction called serotonin syndrome.

Osteoporosis / Bone health

Anastrozole significantly lowers oestrogen levels, which can rapidly decrease bone mineral density and increase your risk of fractures. Your doctor should monitor your bone health before and during treatment.

Food and drink warnings

Alcohol

You should avoid or strictly limit alcohol while taking venlafaxine. Combining the two can increase drowsiness, dizziness, and impair your coordination and judgement. In some cases, it may also worsen symptoms of depression or anxiety.

Caffeine (Coffee, tea, energy drinks)

Venlafaxine can sometimes increase blood pressure or heart rate. High intake of caffeine can worsen these effects, potentially leading to palpitations, jitteriness, or difficulty sleeping. Monitor your intake if you feel these symptoms.

Using other medicines

Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.