Exemestane (Aromasin)

At a glance

Exemestane is a medicine used in specialist cancer care. Brand names include Aromasin. The practical instructions depend on the exact prescription and product supplied.

Your prescription and the instructions for your own product take priority over a general guide. Keep the medicine leaflet as well as your treatment plan, especially if the brand or formulation changes.

You do not need to remember every possible side effect. Start with the administration instructions and the section on urgent help. Most people experience only some of the effects described here. Tell your team about difficulties early: supportive treatment, a planned pause or a different medicine may make treatment easier to continue.

How it works

Exemestane is a steroidal aromatase inhibitor. It lowers oestrogen production by inactivating aromatase. The word steroidal describes its chemical structure; it does not mean that you need a corticosteroid such as prednisolone with it.

Is this treatment suitable for me?

The team considers hormone-receptor results and whether ovarian hormone production has stopped or is being reliably suppressed. Exemestane may be used with another anticancer medicine, whose additional side effects and monitoring need separate explanation.

Your oncologist considers the biology of the cancer, treatments already received, other illnesses and your preferences. The aim may be to reduce the chance of cancer returning, control cancer that is present, or relieve symptoms. Ask which aim applies to you and how benefit will be assessed. The same medicine can be used for different lengths of time in different treatment plans.

A brand name alone does not tell you whether a medicine is suitable. The dose, formulation and other medicines in the plan also matter. Discuss the possible benefits and risks with your care team.

Before treatment

Mention fractures, osteoporosis, low vitamin D, joint problems, liver or kidney disease and use of oestrogen products. Baseline bone-health assessment is important. Ask the team to check vitamin D before treatment and address any deficiency. They should also confirm menopausal or ovarian-suppression status.

Bring an up-to-date list of prescription medicines, pharmacy medicines, supplements and traditional or herbal remedies. Include medicines used only occasionally, creams containing hormones, and anything recently stopped. Mention previous allergies and describe what happened, rather than only naming the drug. Your pharmacist can check the whole list together.

Tell the team about any planned operation, dental procedure, travel or difficulty attending appointments. Discuss costs and supply before the first dose if obtaining regular refills may be difficult. Agree who will arrange repeat prescriptions and tests. Keep your own hospital's daytime and out-of-hours contact details where you and a caregiver can find them quickly.

If pregnancy is possible, the team should arrange a pregnancy test before treatment starts; the US product information specifies within the preceding seven days.

How to take or receive treatment

The usual dose is 25 mg once daily after a meal. Use the same meal each day if that makes remembering easier. Swallow the tablet with water. A higher dose may sometimes be prescribed because of an unavoidable interaction, but do not increase it yourself.

If a tablet is forgotten, take it when remembered unless the next dose is nearly due; then skip it. Do not double. Do not automatically replace a vomited dose. Ask the pharmacist for product-specific advice if swallowing is difficult or meals are irregular.

Swallow the medicine as directed for your product. Do not crush, open, dissolve or divide it unless the oncology pharmacist has confirmed a safe method for that exact formulation. Some products have a specific dispersion method; this is different from crushing tablets yourself. Tell the team before starting if swallowing is difficult or you use a feeding tube.

After vomiting a dose, do not automatically take a replacement because some medicine may already have been absorbed. Follow the drug-specific instructions in this section and call the team if vomiting persists. A missed dose and a vomited dose are different situations, so use the relevant rule.

Store tablets or capsules in their labelled packaging, out of children's sight and reach, away from heat and moisture, within the temperature limits on the pack. Keep any drying container supplied in the bottle. Ask before transferring anticancer medicines into an organiser. A caregiver should avoid direct contact with damaged tablets or powder and follow the pharmacy's handling advice; pregnant caregivers should not handle damaged anticancer tablets. Wash hands after handling. Return unwanted doses to a pharmacy rather than putting them into household waste or a drain.

Use a calendar or a phone reminder that records what was actually taken or given. A tick made after a dose is more useful than one made in advance. If someone helps with medicines, agree who records each dose so it is not accidentally repeated. Keep the drug name, strength and current instructions together; an old prescription may no longer describe your current dose.

Contact the treating team if a supply problem or illness is likely to interrupt treatment. Do not stretch the supply by taking smaller doses or lengthening intervals yourself. If you receive too much medicine, seek urgent advice and have the packaging and dose times available. Do not induce vomiting.

Monitoring your treatment

Bone density and fracture risk are reviewed, and low vitamin D is treated when identified. Blood tests may check general health, liver function and other concerns. If ovarian suppression accompanies exemestane, hormone monitoring and on-time injections remain important.

Monitoring has two purposes: checking whether treatment is helping and detecting problems that may be silent at first. Your schedule depends on the medicine, any partner treatment and your general health. Ask which results need to be reviewed before the next prescription or injection, and who will contact you if a result is abnormal.

Record symptoms that affect eating, walking, sleep or daily activities, along with when they began. Bring this record to appointments. A single symptom or blood result rarely explains the whole picture; the team may compare trends, examination findings and scans. Feeling well is welcome, but it does not remove the need for planned monitoring.

Common side effects

Effects to discuss with your team

Hot flushes, sweating, joint pain, fatigue, sleep difficulty, nausea, headache and hair thinning may occur. Gentle activity and symptom treatment can help some joint problems. Persistent tingling or hand pain should be assessed for causes such as carpal tunnel symptoms.

Lowering oestrogen can cause hot flushes, vaginal dryness, disturbed sleep and aching or stiff joints. Gentle regular movement may help stiffness, but persistent pain deserves assessment. A non-hormonal vaginal moisturiser or lubricant may help dryness; ask the team before using vaginal oestrogen or another hormone-containing product. Report unexpected vaginal bleeding, particularly after menopause.

Bone density can fall during aromatase inhibitor treatment. A bone-density scan measures bone strength and is different from a scan looking for cancer. Your team may recommend calcium through food, vitamin D when needed, and a bone-protecting medicine according to your risk. More calcium is not always better, particularly with kidney stones or abnormal calcium results.

An aromatase inhibitor alone does not adequately suppress oestrogen made by functioning ovaries. If you are not definitely postmenopausal, the team may prescribe ovarian suppression and check hormone levels. Periods stopping after chemotherapy does not always establish permanent menopause. If ovarian suppression is part of your plan, keep those injections on time and report returning periods. Do not add an old supply of tamoxifen to an aromatase inhibitor unless the oncologist has explicitly prescribed the change.

Making symptoms easier to manage

Tell the team which symptom is causing the most difficulty. Describe its effect on ordinary tasks: for example, whether pain prevents dressing or tiredness stops you preparing food. This helps the team choose practical support and judge whether treatment needs adjustment. Avoid waiting until the next routine visit if symptoms are worsening.

For mild nausea, try smaller meals and regular sips of fluid, following any food rule for the medicine. Ask about an anti-sickness medicine if needed. Repeated vomiting, inability to keep fluids down or very little urine needs prompt advice. If you have been told to restrict fluids for another illness, use that plan rather than forcing extra drinks.

Energy and emotional wellbeing

Pace demanding activities and allow rest, but keep some gentle movement in your day if you can. Persistent exhaustion deserves assessment; poor sleep, anaemia, low mood and other illnesses may contribute. Tell the team about persistent anxiety, sadness or loss of interest. If you feel at risk of harming yourself, seek emergency help and ask someone to stay with you.

Important side effects

The effects below are important because they may require tests or a change in treatment. They are not a prediction that you will develop them. New symptoms can also come from the cancer or an unrelated illness. Reporting them promptly allows the team to work out the cause; do not assume that everything is a routine treatment effect.

Bone loss and fractures are important longer-term risks. Liver inflammation and severe allergic reactions are less common but significant. Severe or persistent symptoms should not be dismissed because the treatment is a daily hormonal tablet rather than an infusion.

Tendon inflammation and tendon tears have also been reported. Tell the team about new pain or swelling around a tendon, especially if movement becomes difficult. Rest the affected area while seeking advice; sudden pain with a snapping sensation or loss of function needs urgent assessment.

Other medicines and vaccinations

Oestrogen-containing treatment can oppose the intended effect. Rifampicin, certain anticonvulsants and St John's wort can reduce exemestane exposure. Tell the pharmacist before a new antibiotic or seizure medicine starts. Do not copy the interaction-based dose increase from another person's prescription.

Ask the oncology pharmacist to check new medicines before you start them, including antibiotics prescribed elsewhere. Do not stop essential treatment for another illness on your own. If an interaction is possible, the prescribers can choose an alternative, adjust a dose or arrange monitoring. Herbal products labelled natural can still alter drug levels or have hormone-like effects.

Vaccination advice depends on your complete treatment plan. Hormone treatment alone does not automatically mean that every vaccine is unsuitable. Ask about influenza, COVID-19 and other recommended vaccines; live vaccines need a specific check if you also receive chemotherapy, an immune-suppressing medicine or certain doses of steroid. Tell the vaccination service all the treatments you receive.

Everyday life

Food and movement

Aim for regular meals with enough protein and a varied range of foods that you can tolerate. Tell the team about unplanned weight loss, rapid weight gain or difficulty eating. A dietitian can adapt advice to diabetes, kidney problems, bowel symptoms or a restricted appetite. Do not start a restrictive diet or high-dose supplement as a substitute for treatment.

Choose activity that suits your strength and balance. Short walks or gentle exercises may be easier to sustain than occasional strenuous sessions. If cancer affects your bones, or you have osteoporosis, ask which movements and resistance exercises are safe before starting a new programme. New focal bone pain should be assessed rather than exercised through.

Work and travel

Many people continue some usual activities, but flexibility helps while you learn how treatment affects you. Discuss rest breaks, shorter hours or help with physically demanding work if needed. Avoid driving or operating machinery when dizzy, sleepy, confused or affected by visual symptoms. Follow any additional driving advice after a seizure or loss of consciousness.

Plan travel around prescriptions, injections and tests. Carry an up-to-date medicine list and enough supply for the agreed trip, with advice about storage and time-zone changes. For long journeys, discuss mobility and your individual clot risk. Do not start aspirin or a blood thinner simply because you are travelling.

Relationships and support

Changes in energy, body image or sexual function can affect relationships. You can ask for help privately, with or without a partner present. There may be practical measures or specialist support for discomfort and intimacy. A caregiver can help record symptoms and organise appointments while leaving treatment decisions and personal information under your control.

Fertility, pregnancy and breastfeeding

Avoid pregnancy during treatment. The US label advises effective contraception during treatment and for one month afterwards, and no breastfeeding during treatment or for one month after the last dose. Use the non-hormonal method agreed with your team and account for any partner medicine's longer interval.

Tell the team before treatment if having children in the future matters to you. Fertility preservation needs discussion before exposure where possible. Reduced fertility is not the same as reliable contraception, and an absence of periods or reduced sexual function does not prove that pregnancy is impossible.

Ask your team which contraception to use and how long to continue it, taking account of every medicine in your regimen. A partner drug may require a longer precaution period than this medicine alone. If pregnancy is suspected in you or a partner during a risk period, contact the treating team promptly for individual advice. Do not make pregnancy or breastfeeding decisions from a generic time interval without checking your own treatment plan.

After treatment

When switching from or to another endocrine medicine, confirm the exact date of the change. Do not take the old and new tablets together unless explicitly prescribed. Continue bone-health care and report symptoms that do not improve after treatment ends.

Before a planned stop, confirm which medicines end, which continue, and when the next review is due. Return unused medicine through the pharmacy's recommended route; do not give it to another person. Keep a record of the last dose and any side effects that still need follow-up.

Changes caused by treatment may settle gradually, and some need ongoing support. Report persistent symptoms or new problems after treatment rather than assuming they will disappear on their own. Continue the agreed follow-up and screening plan. If treatment is being changed, ask your team to help you update your treatment schedule so that old and new instructions are not accidentally combined.

Common questions