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. You will have blood work monitored for high calcium levels and to monitor the function of your liver, since both can be affected by taking fluoxymesterone.
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). Keep containers out of reach of children and pets.
Where do I get this medication?
This medication is available through retail and mail order pharmacies. Your oncology team will give you a prescription, which you can fill at your local pharmacy.
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
Below are some of the possible side effects and suggestions for dealing with them. Be sure to tell your oncology team if you are experiencing any of these problems.
Nausea and/or Vomiting
This medication can cause an upset stomach. Taking your dose with food or milk can help prevent this from happening. 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 antacids, (e.g. milk of magnesia, calcium tablets such as Tums), saltines, or ginger ale to lessen symptoms.
Call your doctor or nurse if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.
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.
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.
Weakening of the Bones (Osteoporosis)
Women who take hormone therapy for extended periods of time are at risk for bone thinning (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. You may have a bone density scan (DEXA scan) to assess your bone health. If your provider determines that you are at high risk of developing osteoporosis, they may recommend additional treatment with a type of medication called a bisphosphonate to help strengthen the bones.
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.
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 or father a child while on this medication. Effective birth control is necessary during treatment and for at least 6 months after treatment, even if your menstrual cycle stops or you believe you are not producing sperm. 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. Do not breastfeed while taking this medication.