How does this medication work? What will it do for me?

Medroxyprogesterone acetate belongs to the class of medication known as progestogens. It is used to prevent pregnancy. It works by preventing a woman's egg from completely developing. It also thickens the mucus around the cervix, making it harder for sperm to reach the egg. Medroxyprogesterone acetate is also used to treat endometriosis.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each mL contains 150 mg medroxyprogesterone as acetate. Nonmedicinal ingredients: methylparaben, propylparaben, polyethylene glycol 3350, polysorbate, sodium chloride, hydrochloric acid and/or sodium hydroxide to adjust pH, and water for injection.

How should I use this medication?

Birth control: The recommended dose is 150 mg injected into a muscle by a health care professional every 3 months, usually started within the first 5 days after the onset of a normal menstrual period. Intervals between injections must not be more than 13 weeks. If an injection is not received within 13 weeks, a pregnancy test should be done before any further treatment with medroxyprogesterone.

If the injection is given within the first 5 days after the onset of a normal menstrual period, it is effective from the day of injection. However, if it is given later during the menstrual cycle, it may not be effective for the first 3 to 4 weeks after the injection. A non-hormonal "back up" method of birth control, such as latex condoms with spermicidal foam or jelly, should be used during this time.

Endometriosis: The usual dose is 50 mg injected into a muscle once a week, or 100 mg injected into a muscle every second week for at least 6 months.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is very important that this medication be used exactly as prescribed by the doctor. This preparation is not to be used intravenously (injected into a vein). If you miss an appointment to receive medroxyprogesterone acetate injection, contact your doctor as soon as possible to reschedule your appointment.

Store this medication at room temperature, protect it from freezing and light, and keep it out of the reach of children. It should be shaken well just before using.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Medroxyprogesterone should not be used by a woman who:

  • is allergic to medroxyprogesterone or to any of the ingredients of the medication
  • is or may be pregnant
  • has a history of clotting disorders, or who are at increased risk for clotting disorders
  • has a history of heart attack or heart disease
  • has a history of migraines with auras
  • has a history of stroke
  • has liver disease
  • has or may have a cancer that is dependent on progestin
  • has undiagnosed vaginal or urinary tract bleeding
  • has undiagnosed or confirmed breast problems (e.g., cancer)
  • has vision problems because of vascular disease

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain or cramping
  • acne
  • back ache
  • breast swelling or tenderness
  • brown spots on exposed skin, possibly long-lasting
  • changes in menstrual bleeding:
    • increased amounts of menstrual bleeding occurring at regular monthly periods
    • heavier uterine bleeding between regular monthly periods
    • lighter uterine bleeding between menstrual periods
    • stopping of menstrual periods
  • constipation
  • decreased bone mineral density
  • diarrhea
  • dizziness
  • fatigue
  • heartburn
  • hot flashes
  • loss or gain of body, facial, or scalp hair
  • loss of sexual desire
  • mild headache
  • mood changes
  • nausea and vomiting
  • nervousness
  • pain or irritation at place of injection
  • painful periods
  • rapid heartbeat
  • swelling of face, ankles, or feet
  • trouble sleeping
  • unusual tiredness or weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • signs of depression (such as feeling sad, losing interest in things you used to enjoy, weight changes, changes in sleep habits, feelings of guilt or worthlessness, thoughts of suicide)
  • skin rashes
  • unexpected or increased flow of breast milk
  • yellowing of the skin or eyes, which could be signs of liver damage

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • abdominal or stomach pain (sudden, severe, or continuing)
  • shortness of breath (sudden or unexplained)
  • signs of blood clots (e.g., coughing up of blood, pains in chest, groin, or leg (especially in calf of leg), swelling or redness in the legs)
  • signs of heart attack (e.g., sudden chest pain; pain radiating to back, down arm, jaw; sensation of fullness of the chest; nausea; vomiting; sweating; anxiety)
  • signs of stroke (e.g., confusion; sudden or severe headache; sudden loss of coordination; sudden change in vision; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Blood clots: This medication has been associated with blood clots developing in the bloodstream. These blood clots may form anywhere in the body but are more noticeable when they occur in the large muscles, lung, brain (stroke), or heart (heart attack). If you experience pain in the chest or leg, unexplained shortness of breath, blurred vision or slurred speech, contact your doctor immediately.

Certain conditions such as long-term bed confinement may make blood clots more likely. Discuss with your doctor the risks and benefits of temporarily stopping this medication if you are scheduled for surgery, and let all doctors involved in your care know that you are taking this medication.

Bone loss: The amount of bone loss depends on how long the woman uses this medication. This bone loss may not be completely reversible. You should discuss these risks with your doctor. This risk for bone effects may be greatest in early adulthood and adolescence.

Medroxyprogesterone causes bone loss, and adolescent women whose bones are still forming and have not yet reached their peak bone mass should discuss any concerns with their doctor. It is not known if this will influence peak bone mass and increase the risk of osteoporosis in the future. If you are considering using this medication, discuss the risks and benefits with your doctor.

Cancer: For some women, there may be an increased risk of breast cancer associated with the use of medroxyprogesterone acetate injection. Long-term studies showed no increased risk of ovarian, liver, or cervical cancer. Talk to your doctor if you have any concerns about this medication.

Cigarette smoking: There is an increased risk of negative side effects on the heart and blood vessels in women who smoke and are using medroxyprogesterone acetate. If you smoke, discuss the benefits of stopping smoking with your doctor or pharmacist. There are tools that are available to make this easier.

Diabetes: Some women receiving medroxyprogesterone experience decreased blood glucose control. For this reason, women with diabetes should carefully monitor their blood glucose while receiving medroxyprogesterone acetate. Discuss with your doctor the ideal frequency with which you should check your blood glucose.

Fertility: Research indicates there is no evidence that medroxyprogesterone causes infertility. It may take some time for the injection to wear off, and most women must wait about 6 to 8 months after the last injection to start ovulating, having regular periods, and be able to become pregnant.

Fluid retention: Since progestogens may cause some degree of fluid retention, conditions such as epilepsy, migraine, asthma, or reduced heart or kidney function might be influenced by this medication.Women who have any of these conditions should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

High blood pressure: The fluid retention mentioned above can contribute to increased blood pressure. Women who are treating high blood pressure or may be at risk of developing high blood pressure should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Irregular menstrual patterns: Menstrual patterns commonly change following the use of medroxyprogesterone. This includes irregular or unpredictable bleeding or spotting or, rarely, heavy or continuous bleeding. If undiagnosed vaginal bleeding occurs, or if abnormal bleeding persists or is severe, consult your doctor.

As women continue to use medroxyprogesterone, fewer experience irregular bleeding patterns and more do not menstruate at all. By Month 12, about 55% of women no longer have periods, and by Month 24, about 68% of women using medroxyprogesterone do not have periods. Because of the prolonged effect of the medication, re-establishment of menstruation may be delayed and difficult to predict.

Liver disease: Women who at risk of or who have liver disease should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. The doctor will probably monitor liver function with regular blood tests. If you develop signs of liver disease (such as yellowing of the skin or eyes; or swelling, pain, or tenderness in the upper abdominal area), contact your doctor as soon as possible.

Migraine and headache: The onset or worsening of a migraine or the development of new types of recurrent, persistent, or severe headaches should be reported to your doctor.

Sexually transmitted infections: This medication does not protect against sexually transmitted infections, including HIV/AIDS. For protection against these, use latex condoms.

Weight changes: Weight gain may be associated with the use of medroxyprogesterone. The majority of studies report an average weight gain of 2.5 kg at the end of one year, but only 2% of women stopped treatment due to excessive weight gain.

Pregnancy: This medication should not be used by pregnant women. To help ensure a woman is not pregnant at the time of the first injection, it is recommended that the first injection be given only within the first 5 days of the onset of a normal menstrual period, or only within the first 5 days after childbirth if the mother is not breast-feeding.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking medroxyprogesterone, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children. Medroxyprogesterone is not intended to be used in young women before menstruation begins (menarche).

What other drugs could interact with this medication?

There may be an interaction between medroxyprogesterone acetate injection and any of the following:

  • aminoglutethimide
  • aprepitant
  • barbiturates (e.g., phenobarbital, butalbital)
  • certain antiseizure medications (e.g., carbamazepine, lamotrigine, phenytoin)
  • certain benzodiazepines (e.g., alprazolam, clonazepam, diazepam)
  • cholestyramine
  • cyclosporine
  • griseofulvin
  • isotretinoin
  • mycophenolate
  • nevirapine
  • rifabutin
  • rifampin
  • tranexamic acid
  • tretinoin
  • voriconazole

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.