Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

The following side effects may be caused by blood clots, which could lead to a heart attack or a stroke. Stop taking this medicine and get emergency help immediately if any of the following side effects occur:

More common

Shortness of breath

Less common

Chest pain

Rare

Continuing or severe nervousness; cough; dizziness or lightheadedness; fainting; fast heartbeat; heart attack; increased sweating; nausea; pain in chest, groin, or legs, especially the calves; severe, sudden headache; slurred speech; severe and sudden, unexplained shortness of breath; sudden loss of coordination; sudden, severe weakness or numbness in arm or leg; vision changes

Also, check with your doctor as soon as possible if any of the following side effects occur:

Less common

Bone fracture; breast pain; chills, fever, or flu-like symptoms; mental depression; swelling of feet or lower legs

Rare

Vaginal bleeding

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Back pain; bone pain; hot flashes (sudden sweating and feeling of warmth); joint pain; muscle pain

Less common

Anxiety; confusion; constipation; diarrhea; dry mouth; headache; increased thirst and urination; loss of appetite or weight loss; metallic taste; skin rash or itching; sleepiness; spinning or whirling sensation causing loss of balance; stomach pain or upset; trouble sleeping; unusual tiredness; vomiting; weakness; weight gain

Letrozole sometimes causes a loss of hair.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.