Elacestrant (Orserdu™)

Author: Marisa Healy, BSN, RN
Content Contributor: Kristin Markiewicz, PharmD, BCOP
Last Reviewed: January 31, 2023

Pronounce: EL-a-KES-trant

Classification: Estrogen receptor antagonist

About: Elacestrant (Orserdu™)

Elacestrant is an estrogen receptor antagonist, also called an antiestrogen or estrogen blocker. It works by blocking estrogen receptors in breast tissue. While estrogen may not cause breast cancer, it is needed for the cancer to grow in some breast cancers. When estrogen is blocked, the cancer cells that feed off estrogen may not be able to survive. Your tumor may need to be tested for certain biomarkers and receptors before starting treatment with elacestrant.

How to Take Elacestrant

Elacestrant comes in tablet form to be taken orally (by mouth). It should be taken around the same time every day. This medication should be swallowed whole and taken with food. Do not crush, chew, or break the tablets. Do not take any tablets that are cracked or broken. Talk with your provider if you have trouble swallowing pills.

If you miss a dose and it is less than 6 hours from when you normally take it, take it as soon as you remember. If it has been more than 6 hours, skip that dose and take your next scheduled dose. Do not double your dose. Instead, skip the missed dose and continue your regular schedule.

It is important to make sure you are taking the correct amount of medication every time. Before every dose, check that what you are taking matches what you have been prescribed.

The blood levels of this medication can be affected by certain medications and supplements. These include: itraconazole, fluconazole, rifampin, and efavirenza, among others. Make sure your providers are aware of all medications (over-the-counter and prescription) and supplements you are taking.

Storage and Handling

Store this medication at room temperature in the original container. If you usually use a pillbox, ask your pharmacist if you can with this medication. If a caregiver prepares your dose for you, they should consider wearing gloves or pour the pills directly from their container into the cap, a small cup, or directly into your hand. They should avoid touching the pills. They should always wash their hands before and after giving you the medication. Pregnant or nursing women should not prepare the dose for you.

Ask your oncology team where to return any unused medication for disposal. Do not flush down the toilet or throw in the trash.

Where do I get this medication?

Certain cancer medications are only available through specialty pharmacies. If you need to get this medication through a specialty pharmacy, your provider will help you start this process. Where you can fill your prescriptions may also be influenced by your prescription drug coverage. Ask your health care provider or pharmacist for help in identifying where you can get this medication.

Insurance Information

This medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without adequate prescription drug coverage. Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients, may also be available. Your care team can help you find these resources, if they are available.

Possible Side Effects

There are a number of things you can do to manage the side effects of elacestrant. Talk to your care team about these recommendations. They can help you decide what will work best for you. These are some of the most common or important side effects:

Muscle or Joint Pain

Your healthcare provider can recommend medications and other strategies to help relieve pain.

Nausea and/or Vomiting

Talk to your oncology care team so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy or acidic foods (lemons, tomatoes, oranges). Try saltines or ginger ale to lesson symptoms.

Call your oncology care team if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.

Increased Cholesterol/Triglycerides

Elacestrant can increase the cholesterol and triglyceride (lipid) levels in your blood. Your healthcare providers will monitor your lipid levels before, during and after and may prescribe medication to help manage increased lipid levels.

Liver Toxicity

This medication can cause liver toxicity, which your oncology care team may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown, or you have pain in your abdomen, as these can be signs of liver toxicity.

Low Red Blood Cell Count (Anemia)

Your red blood cells are responsible for carrying oxygen to the tissues in your body. When the  red cell count is low, you may feel tired or weak. You should let your oncology care team know if you experience any shortness of breath, difficulty breathing or pain in your chest. If the count gets too low, you may receive a blood transfusion.


Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.

Sexual and Reproductive Concerns

This medication may affect your reproductive system, resulting in the menstrual cycle or sperm production becoming irregular or stopping permanently. Women may have menopausal effects such as hot flashes and vaginal dryness. In addition, the desire for sex may decrease during treatment. You may want to consider sperm banking or egg harvesting if you may wish to have a child in the future. Discuss these options with your oncology team.
Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment and for at least 1 week after treatment, even if your menstrual cycle stops or you believe you are not producing sperm. You should not breastfeed while receiving this medication and for at least 1 week after your last dose.