Classification: hormone therapy
About Fluoxymesterone (Halotestin®)
Fluoxymesterone is an androgen hormone therapy. Androgens are hormones that stimulate the development of male characteristics. Fluoxymesterone works as an androgen, which opposes the activity of estrogen, slowing the growth of estrogen-receptor positive breast cancer.
How to take Fluoxymesterone
Fluoxymesterone comes in a tablet form to be taken orally (by mouth). The dose will depend upon the reason you are being prescribed the medication and may be given once a day or split up into 3-4 doses each day.
Storage and Handling
Store your medication in the original, labeled container at room temperature and in a dry location (unless otherwise directed 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 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?
This medication is available through retail or mail order pharmacy. Your oncology team will work with your prescription drug plan to identify an in-network, retail or mail order pharmacy for medication distribution.
This medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without prescription drug coverage. Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients, may be available. Your care team can help you find these resources, if they are available.
Possible Side Effects of Fluoxymesterone
There are a number of things you can do to manage the side effects of fluoxymesterone. 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:
A common side effect of fluoxymesterone is swelling of the face, hands and feet, or sudden weight gain, which can become uncomfortable and cause stress on the heart. Notify your provider if you notice any swelling to determine the best management.
Weakening of the Bones (Osteoporosis)
You may be advised to take calcium and vitamin D supplements to help prevent bone loss. Weight bearing exercise and a healthy diet rich in calcium and vitamin D can also help protect your bone health. Your doctor will check your bone health before starting therapy. This is done with a bone density scan (DEXA scan). Women with no weakening of bones prior to aromatase inhibitor therapy will have a follow-up scan around one year after starting therapy, and then every one to two years. If the scan shows that you already have some bone weakening, your doctor may order a type of medication called a bisphosphonate. These therapies have been shown to protect the bones from bone loss in women taking aromatase inhibitors. If the bone density remains stable, scans can then be done every two years.
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 lessen 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 Appetite and Weight Gain
Because fluoxymesterone functions as an androgen it may increase your appetite and therefore cause weight gain. Speak to your provider about how a healthy diet and lifestyle can help manage this side effect.
Liver Toxicity and Secondary Liver Cancer
This medication can cause liver toxicity and in rare, but serious cases, liver cancer which your doctor 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 the abdomen, as these can be signs of liver toxicity.
Some patients will develop changes in their mood, including anxiety, depression, or mood swings. Talk to your provider if this occurs.
High Blood Sugar
This medication can cause elevated blood sugar levels in patients with and without diabetes. Your oncology care team will monitor your blood sugar. If you develop increased thirst, urination or hunger, blurry vision, headaches or your breath smells like fruit, notify your healthcare team. Diabetics should monitor their blood sugar closely and report elevations to the healthcare team.
This medication can cause elevated lipid (cholesterol) levels. You will have blood tests to monitor your lipid levels.
Sexual & Reproductive Concerns
This medication may affect your reproductive system, because the female hormone estrogen is being blocked. This leads to a number of side effects that may result in the menstrual cycle becoming irregular or stopping permanently. Women may experience menopausal effects including hot flashes and vaginal dryness. A woman may see changes in her skin, including acne and an increase in facial hair. The clitoris may become enlarged and the voice may deepen. In addition, the desire for sex may decrease or increase during treatment.
Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant while on this medication. Effective birth control is necessary during treatment, even if your menstrual cycle stops. You may want to consider egg harvesting if you may wish to have a child in the future. Discuss these options with your oncology team. Do not breastfeed while taking this medication.