What are the risks of taking progesterone (Prometrium)?

• Blood clots, heart attacks, and strokes:
  Risk factors: Taking progesterone with estrogens; High blood pressure; diabetes; high cholesterol; smoking; overweight; history of systemic lupus erythematosus (LE); personal or family history of blood clots and strokes. 
  
  Taking progesterone or any progestin therapy with estrogen medications can increase your risk of developing blood clots leading to a heart attack, stroke, or a pulmonary embolism (a life-threatening blood clot in the lungs). Smoking and a history of blood clots are the two most significant risk factors. If any of these cardiovascular events occur or are suspected, estrogen plus progestin therapy should be discontinued immediately.

• Breast cancer:
  Risk factors: Personal or family history of breast cancer; long-term use of progesterone and estrogen together. 
  
  Taking progesterone and estrogen together can raise your risk of developing breast cancer.. Perform breast self-examinations at least monthly. Talk to your healthcare provider about early detection and other ways to protect yourself, especially if you or someone in your family has had a history of breast cancer.

• Dementia:
  Risk factors: Age 65 and older; taking progesterone with estrogens.
  
  Taking progesterone and estrogen medications together can raise your risk of developing dementia. This risk is higher if you start using this combination of medicines at 65 or older. Progesterone should not be used to prevent dementia. Talk to your healthcare provider if this concerns you.

• Dizziness and drowsiness:
  Progesterone can make you drowsy; this effect is temporary but can affect your ability to drive or focus. It is best to take this medication at bedtime. You should not take progesterone if you have less than 8 hours before driving or performing activities that require mental focus.  

Injection form only:

• Pneumonia:
  Risk factor: Progesterone injection containing sesame oil
  Certain progesterone injections can contain sesame oil that potentially leads to an increased risk of having pneumonia. This particular type of pneumonia can affect your ability to breathe effectively. Seek emergency medical care immediately if you experience sudden shortness of breath, cough, fever, and chest pain that worsens with a deep breath. This condition can be life-threatening and can happen during the first 2 to 4 weeks after using this medication. 

Other dosage forms: 

• Fluid retention:
  Risk factors: heart failure; history of kidney disease
  Progesterone can cause extra fluid retention in the body. The risk is higher if you have heart failure or kidney diseases. Let your doctor know if you have problems with fluid retention (swelling) before using progesterone. Inform your doctor immediately if you notice swelling or rapid weight gain or if you have sudden, unusual shortness of breath. 
• Vision problems:
  Risk factor: taking progesterone with estrogens.
  Taking progesterone with estrogens can cause an increased risk of developing blood clots in your retina ( a layer of tissue in the back of the eye) - this is a medical emergency. Call 911 or seek emergency medical care if you have severe double vision, unexplained, sudden loss of vision, or if your eyeball is bulging out of its socket. Progesterone and estrogens must be discontinued permanently.