Estramustine (Emcyt®)

Author: Marisa Healy, BSN, RN
Last Reviewed: August 3, 2025

Pronounce: ESS-truh-muss-TEEN

Classification: Antineoplastic Agent

About Estramustine (Emcyt®)

Estramustine is a combination of the chemotherapy nitrogen mustard and a type of estrogen called estradiol. Estramustine affects the microtubular network in cells needed for cell division and other cellular functions.

The estradiol in estramustine also lowers your body's production of testosterone. Most prostate cancers need a supply of the male hormone testosterone to grow. Without testosterone, the cancer cells may either grow more slowly or stop growing, helping to stop the growth and spread of cancer cells.

How to Take Estramustine

This medication comes in a capsule. Your dose is based on your body size. The capsule should be swallowed whole. It should not be open, broken, or chewed. It is taken in 3 or 4 doses a day on an empty stomach (1 hour before or 2 hours after a meal). You should not take this medication with milk or other foods or supplements high in calcium or magnesium (including antacids), as they may affect how it is absorbed. 

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.

Be sure to tell your care team about any allergies to either estradiol or nitrogen mustard, or if you have a clotting disorder.

Storage and Handling

Store your medication in the original, labeled container in the refrigerator (unless otherwise told by your healthcare provider or pharmacist). This medication should not be stored in a pillbox. Keep containers out of reach of children and pets.

If a caregiver prepares your dose for you, they should consider wearing gloves or pour the pills directly from the 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?

Estramustine is available through select specialty pharmacies. Your oncology team will work with your prescription drug plan to identify an in-network specialty pharmacy for distribution of this medication and shipment directly to your home.

Insurance Information

This medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals depending upon 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 of Estramustine

There are a number of things you can do to manage the side effects of estramustine. 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:

Breast Tenderness or Increase in Breast Tissue

An increase in breast tissue (gynecomastia) or breast tenderness may develop. Your healthcare team can suggest medications to relieve the tenderness. In rare cases, radiation can be given to relieve severe tenderness.

Fluid Retention/Swelling

Some patients may develop fluid retention, which can cause swelling in the feet, ankles, or face, and weight gain. Fluid can also build up in the lungs and cause you to feel short of breath. Tell your care team if you have any swelling, unexpected weight gain, or shortness of breath.

High Blood Pressure

This medication can cause high blood pressure (hypertension). You will have your blood pressure checked regularly during therapy. Any hypertension should be treated. If hypertension cannot be controlled, the medication may be stopped. Report any headaches, vision changes, or dizziness to your care team.

Blood Clots and Heart Attack

Estramustine can increase the risk of blood clots and heart attack. If you have symptoms of these problems, contact your healthcare provider right away or call 911. Symptoms can include: swelling, redness, or pain in an extremity (arm or leg), chest pain or pressure, pain in your arm, back, neck, or jaw, or shortness of breath.

High Blood Sugar

This medication can cause high blood sugar levels in patients with and without diabetes. Your care team will monitor your blood sugar. If you develop increased thirst, urination, or hunger, blurry vision, headaches, or if your breath smells like fruit, call your care team. Diabetics should monitor their blood sugar closely and report elevations to the healthcare team.

Sexual and Reproductive Changes

This drug can affect your reproductive system, causing sperm production to become irregular or stop permanently. In addition, you may experience erectile dysfunction or a decreased desire for sex during treatment. Talk to your urologist about options for treating erectile dysfunction.

Exposure of an unborn child to this medication could cause birth defects, so you should not father a child while on this medication. Effective birth control is necessary during treatment, even if you believe you are not producing sperm. You may want to consider sperm banking if you might wish to have a child in the future. Discuss these options with your oncology team.