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At a glance
Elacestrant is a medicine used in specialist cancer care. Brand names include Korserdu, Orserdu. 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
Elacestrant is a selective oestrogen-receptor degrader, or SERD, taken by mouth. It blocks receptor activity and promotes receptor breakdown. It is distinct from selective receptor modulators such as tamoxifen, so their specific side-effect profiles should not simply be transferred to it.
Is this treatment suitable for me?
Your team checks for oestrogen receptor (ER)-positive, HER2-negative cancer and an activating ESR1 mutation, usually using a blood-based tumour DNA test. They also review menopausal status and previous endocrine and targeted treatments; the required prior treatment depends on the applicable product information. An ESR1 result helps determine whether this particular treatment is suitable; it is not a general inherited-cancer test.
Elacestrant is used to control ER-positive, HER2-negative advanced breast cancer with an ESR1 mutation after earlier endocrine treatment. Your oncologist considers the treatments already received, other illnesses and your preferences. Ask what benefit is expected for you and how it will be assessed. Treatment duration depends on benefit and side effects.
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
Discuss liver disease, high cholesterol or triglycerides, pregnancy potential and all medicines. A lipid profile is needed before treatment. Tell the pharmacist about swallowing problems and check whether the pack is labelled Korserdu or Orserdu.
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 starting. Tell them about previous blood clots and current symptoms such as one-sided leg swelling.
How to take or receive treatment
The usual dose is 345 mg once daily with food, at a consistent time. Food also helps reduce nausea. Swallow tablets intact; do not chew, crush or split them, and do not use damaged tablets.
If a dose is remembered within six hours of its usual time, take it. If more than six hours have passed, skip it and resume the following day. If you vomit after a dose, do not take another that day. The team may prescribe a lower dose for side effects or liver impairment. Dose-reduction schedules differ between product jurisdictions, so use your own prescription rather than copying a reduction from another leaflet.
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
Cholesterol and triglycerides are checked before and periodically during treatment. Liver tests and other blood results may also be reviewed. The cancer response is assessed separately from these safety checks. Tell the team if nausea makes eating or daily dosing difficult.
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
Nausea, vomiting, fatigue, muscle or joint pain, reduced appetite and digestive upset may occur. Taking the dose with food and using prescribed anti-sickness treatment can help. Persistent vomiting or reduced fluid intake requires advice.
Elacestrant acts directly on the oestrogen receptor rather than reducing all oestrogen production. The terms SERD and SERM describe different drug classes, even though both are often discussed as endocrine treatment. Side-effect information for one is not a complete guide to the other.
The medicine is selected using tumour biology, including ESR1 mutation status. A blood sample used to assess tumour DNA is different from a routine blood count. Ask which test was performed and what its result means for this treatment; do not assume the result identifies an inherited mutation in your family.
Lipids deserve particular attention. High cholesterol and triglycerides are usually silent, so feeling well cannot replace blood tests. Diet, other health conditions and medicines all affect lipid levels. The team can decide whether a lifestyle change or medicine is appropriate while continuing to assess the cancer treatment.
Eating with the dose is part of the regimen. If nausea makes meals difficult, ask for a practical food and anti-sickness plan. Keep track of vomiting and missed doses because repeated interruptions can affect treatment delivery. The six-hour missed-dose rule and the instruction not to repeat a vomited dose should be written alongside your daily reminder.
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.
Raised cholesterol or triglycerides can develop without symptoms. Liver impairment can increase exposure and may require adjustment or avoidance. Blood clots have been observed in elacestrant studies, and the team should consider your individual clot risk. A painful, swollen leg needs urgent assessment; sudden breathlessness, chest pain or coughing blood needs emergency care.
When to get urgent help
New one-sided painful leg swelling needs urgent assessment; sudden breathlessness or coughing blood requires emergency care.
Seek prompt advice for repeated vomiting, dehydration, jaundice or severe persistent abdominal pain. Severe allergy symptoms, collapse or severe chest pain require emergency care. Do not take extra tablets to compensate for vomiting.
Get emergency help immediately for severe breathing difficulty, swelling of the tongue or throat, collapse, a seizure, severe chest pain, or signs of a stroke such as a drooping face, new arm weakness or difficulty speaking. Do not drive yourself if you are faint, confused or seriously unwell, and do not wait for an oncology callback before seeking emergency care.
Contact your oncology team the same day for repeated vomiting, dehydration, new jaundice, a rapidly worsening rash, or a sudden major change in how you feel. Fever with shaking chills or feeling acutely unwell also needs prompt advice, particularly if you receive another treatment that can lower white blood cells. Follow the temperature threshold and emergency instructions given for your complete regimen.
When asking for help, give the medicine name, last dose or injection date, other cancer treatments and main symptoms. Mention any blood thinner or steroid. If you cannot reach the team and the problem is urgent, use your hospital's emergency service rather than waiting for the next appointment.
Other medicines and vaccinations
Strong or moderate CYP3A4 inhibitors and inducers can substantially change exposure and should generally be avoided. Examples needing review include certain antibiotics, antifungals, seizure medicines and St John's wort. Avoid grapefruit products. Elacestrant can also affect transporter-substrate medicines such as digoxin or some statins.
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
Effective contraception is advised during treatment and for one week after the last dose for patients who could become pregnant and males with partners who could become pregnant. Do not breastfeed during treatment or for one week afterwards. Discuss fertility before starting and confirm any longer interval from other medicines.
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
Do not substitute fulvestrant injections or another endocrine tablet when elacestrant ends. The next treatment depends on a new oncology assessment. Lipid or liver abnormalities may require follow-up even after the tablets stop.
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
Why do I need an ESR1 test?
The result helps identify whether the cancer has a receptor change relevant to elacestrant treatment. Your team interprets it with other tumour features and previous treatment. A positive or negative result does not by itself describe every treatment option.
Are Korserdu and Orserdu different active medicines?
Both contain elacestrant, but they are brand names used in different markets. Local prescribing details, including dose-reduction instructions, may differ. Check the exact pack and prescription rather than using another country's leaflet for self-adjustment.
What if I remember the tablet seven hours late?
Skip that dose and take the next dose the following day at the usual time. The six-hour window is specific to elacestrant. Do not take two doses together or add an extra tablet the next morning.
Why check cholesterol when I feel well?
Elacestrant can raise cholesterol and triglycerides without causing obvious symptoms. Blood tests allow the team to address this before it becomes a longer-term problem. Do not stop a prescribed lipid-lowering medicine without an interaction review and a plan.
Is this the same as chemotherapy?
It is a hormonal or hormone-related treatment, with a different way of working from conventional chemotherapy. It still needs careful prescribing and monitoring. If chemotherapy or a targeted medicine is part of your plan as well, read the information for that medicine because the combined treatment may have additional risks.
How will I know whether treatment is helping?
Your team will explain which symptoms, blood tests, examinations or scans are useful in your situation. Improvement may take time, and some treatments aim to prevent future problems rather than produce a change you can feel. Keep review appointments even when you feel well.
Does having few side effects mean the medicine is not working?
No. Side effects are not a reliable measure of benefit. People can respond to treatment without feeling particularly different. Equally, having troublesome effects does not prove that the cancer is responding. Decisions should use your clinical assessments and test results.
Can I take a break when I feel tired?
Do not create your own breaks or change the dose. Contact the team about fatigue and explain how it affects your day. They may look for another cause, offer support or prescribe a planned adjustment. A supervised change can be safer than repeated unrecorded missed doses.
How long will I need this medicine?
The duration depends on the aim of treatment, response and tolerability. Some plans have a proposed end date; others continue while the balance of benefit and side effects remains favourable. Ask when this will be reviewed. Another person taking the same medicine may appropriately have a different schedule.
Can I use herbal or Ayurvedic products alongside treatment?
Show the pharmacist the ingredients and exact product before using it. Products may affect hormone activity, liver function or the way medicines are handled in the body. Different preparations with similar names can contain different ingredients. A claim that a product is natural does not establish that the combination is safe.
Should I stop my usual medicines?
Continue them unless a prescriber tells you otherwise, but arrange a full interaction check. Include occasional painkillers, supplements and any newly prescribed medicine. If an interaction is found, the team can agree a safe change without leaving another illness untreated.
What should I do if I need surgery or dental treatment?
Tell both teams about your cancer medicine well in advance. They may need to consider bleeding, clotting, steroid support, bone-protecting treatment or appointment timing. Do not stop treatment based on a general internet rule. Ask your team when to pause and restart treatment, and keep the instructions handy.
Can someone else manage my medicines for me?
Yes, if you want that support. Agree one shared record of doses and appointments and ask the pharmacist about safe handling. A caregiver should know the urgent symptoms and where to seek help. Do not share this prescription with anyone else, even if their diagnosis sounds similar.
What if I cannot obtain the next supply or attend the clinic?
Contact the treating service before treatment is due where possible. Give the drug name, formulation and date of the last dose. The team can address supply or reschedule safely. Do not substitute another hormone medicine, ration tablets or assume a delayed injection has no consequences.
When should I seek help instead of waiting for my review?
Use emergency care for severe symptoms such as breathing difficulty, collapse, chest pain, stroke symptoms or a seizure. Contact the oncology team promptly for a new or worsening problem that affects normal activities. The urgent-help section gives additional signs especially relevant to this medicine.
Sources and further reading
Information checked against the following sources on 28 September 2026. Product names and instructions can differ between formulations and countries; your treating team should confirm the instructions for your supplied medicine.
