Progesterone belongs to the class of medications called progestins. It is used in combination with postmenopausal estrogen replacement therapy (ERT) to prevent the estrogen from thickening the lining of the uterus (a condition known as endometrial hyperplasia). This significantly reduces the risk of endometrial cancer. This medication is used for women who have a uterus.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking 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 take this medication if their doctor has not prescribed it.

The recommended dose of progesterone is 200 mg daily taken at bedtime for the last 14 days of estrogen treatment per cycle. Women who take high doses of estrogen should receive a progesterone dose of 300 mg per day. If the dose is 300 mg daily, 200 mg should be taken at bedtime and 100 mg should be taken 2 hours after breakfast for the last 12 to 14 days of estrogen treatment per cycle.

Many things can affect the dose of 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 taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you are using 200 mg daily and miss a dose of this medication at bedtime (i.e., 2 of the 100 mg capsules), take an extra dose of 100 mg (1 capsule) the following morning and continue taking the rest of the capsules as prescribed by your doctor. If you are taking 300 mg daily and miss a dose, skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Each white-to-off-white, round, soft gelatin capsules imprinted with "P1" using black ink and filled with white-to-off-white suspension, contains 100 mg of micronized progesterone. Nonmedicinal ingredients: lecithin, arachis oil, refined (Peanut oil), gelatin 160 (Bloom), glycerol, titanium dioxide, and Opacode WB Black NS-78-17821.

Do not take progesterone if you:

• are allergic to progesterone, peanuts (the capsules contain peanut oil), soya, or any ingredients of this medication
• are or may be pregnant
• have a history of blood clots (e.g., pulmonary embolism, deep vein thrombosis) or blood clotting disorders
• have a tumour dependent on progesterone or estrogen for growth (e.g., breast or endometrial cancer)
• have active liver disease
• have classical migraines
• have endometrial hyperplasia (overgrowth of the lining of the uterus)
• have had a stroke, heart attack, or heart disease
• have partial or complete loss of vision due to blood vessel disease of the eye
• have unexplained abnormal vaginal bleeding

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
• breast pain, swelling, or tenderness
• brown spots on exposed skin, possibly long-lasting
• change of sexual desire
• difficulty concentrating
• difficulty wearing contact lenses
• dizziness
• drowsiness
• fatigue
• headache
• hot flashes
• irritability
• short term joint or muscle pain
• loss or gain of body, facial, or scalp hair
• mood changes
• nausea
• nervousness
• premenstrual syndrome (PMS)
• spinning sensation
• swelling of face, ankles, or feet
• vomiting
• weight gain

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

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

• allergic reaction (e.g., hives, skin rash, itchiness)
• breast lump
• changes in vaginal bleeding, such as:
• vaginal bleeding between regular monthly periods
• increased amounts of menstrual bleeding occurring at regular monthly periods
• lighter vaginal bleeding between menstrual periods
• stopping of menstrual periods
• confusion
• fast or pounding heartbeat
• increased blood pressure
• worsened menstrual cramps
• painful urination
• pain during sexual intercourse
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• symptoms of bladder inflammation (e.g., burning feeling with urination, strong, persistent urge to urinate, blood in the urine, cloudy or strong smelling urine, fever)
• symptoms of gallbladder problems (e.g., intermittent, severe, dull pain in the upper right part of the abdomen, nausea, vomiting, intolerance of fatty or greasy foods)
• vaginal itching or discharge
• worsening headaches or migraines

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

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of a blood clot in blood vessels, such as sudden vision change or dizziness, chest pain, pain and swelling in one leg muscle
• signs of a heart attack (e.g., chest pain or pressure, pain extending through shoulder and arm, nausea and vomiting, sweating)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; 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.

Before you begin using 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 use this medication.

Important information about estrogen:

• Estrogen should be used at the lowest dose that relieves your menopausal symptoms for the shortest time period possible.
• You should not use estrogens with or without progestins to prevent heart disease, heart attacks, or strokes.

Breast and ovarian cancer: Several studies have shown an association between a modest increase in the risk of developing breast cancer or ovarian cancer and the use of hormone replacement therapy during menopause when taken over the long term. Ask your doctor which cancer screening tests you may need and how to perform breast self-examination. Women who have breast nodules, fibrocystic disease, abnormal mammograms, or a strong family history of breast cancer should be closely monitored by their doctor.

Cholesterol: Progesterone can cause increases in cholesterol and other lipids in the blood. If you are at any increased risk of developing increased blood lipids, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Dementia: Women over the age of 65 receiving combined hormone replacement therapy (estrogen and progestin) may be at increased risk of developing dementia (loss of memory and intellectual function). If you are over 65, talk to your doctor about whether you should be tested for dementia.

Depression: Hormones, such as progesterone, have been known to cause mood swings and symptoms of depression. If you have depression or a history of depression, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of depression such as poor concentration, changes in weight, changes in sleep, decreased interest in activities, or notice them in a family member who is taking this medication contact your doctor as soon as possible.

Diabetes: As with other hormone replacement medications, progesterone may cause an increase in blood sugar levels and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Follow-up examinations: It is important to have a follow-up examination 3 to 6 months after starting this medication to assess your response to treatment. Examinations should be done at least once a year after the first one.

Heart disease: Several studies have demonstrated that the use of estrogen and progestins to treat menopausal symptoms is related to an increased risk of heart disease, blood clots, and stroke. If you have risk factors for heart disease or stroke, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: If you have decreased kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Occupational hazards: Temporary and occasional drowsiness or dizziness may occur for some people 1 to 4 hours after taking progesterone, particularly if it is taken with food. If this occurs, avoid activities requiring concentration, good coordination, or reflex action such as driving or operating machinery. In most cases, these problems can be prevented by taking the capsules at the recommended times. The 200 mg dosage should be taken at bedtime. The 300 mg dosage should be divided into two doses: 100 mg 2 hours after breakfast and 200 mg at bedtime.

Vaginal bleeding: Progesterone can cause changes to your normal pattern of vaginal bleeding. If you experience menstrual bleeding that lasts longer or heavier than usual, contact your doctor.

Pregnancy: Do not take progesterone during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

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

There may be an interaction between progesterone and any of the following:

• apalutamide
• apixaban
• barbiturates (e.g., pentobarbital, phenobarbital)
• bosentan
• carbamazepine
• corticosteroids (e.g., dexamethasone, hydrocortisone)
• cyclosporine
• dabigatran
• dabrafenib
• deferasirox
• diabetes medications (e.g., acarbose, canagliflozin, glyburide, insulin, linagliptin, lixisenatide, metformin, rosiglitazone, sitagliptin)
• erdafitinib
• eslicarbazepine
• estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
• heparin
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine)
• HIV protease inhibitors (e.g., indinavir, lopinavir, nelfinavir, ritonavir, saquinavir)
• low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
• mitotane
• modafinil
• phenytoin
• pomalidomide
• primidone
• rifabutin
• rifampin
• rivaroxaban
• St. John's wort
• sarilumab
• siltuximab
• tocilizumab
• warfarin

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.