Letrozole Side Effects
Some side effects of letrozole may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to letrozole: oral tablet
Along with its needed effects, letrozole may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur while taking letrozole:Less common
- Bone fracture
- breast pain
- chest pain
- chills, fever, or flu-like symptoms
- mental depression
- shortness of breath
- swelling of the feet or lower legs
- Continuing or severe nervousness
- dizziness or lightheadedness
- fast heartbeat
- heart attack
- increased sweating
- pain in the chest, groin, or legs, especially the calves
- severe and sudden, unexplained shortness of breath
- severe, sudden headache
- slurred speech
- sudden loss of coordination
- sudden, severe weakness or numbness in the arm or leg
- vaginal bleeding
- vision changes
- Black, tarry stools
- blurred vision
- burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
- chest discomfort
- decreased vision
- dilated neck veins
- extreme fatigue
- increased need to urinate
- irregular breathing
- irregular heartbeat
- painful or difficult urination
- passing urine more often
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- swollen glands
- unusual bleeding or bruising
- unusual tiredness or weakness
- weight gain
- white or brownish vaginal discharge
Some side effects of letrozole may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:More common
- Back pain
- bone pain
- hot flashes (sudden sweating and feeling of warmth)
- joint pain
- muscle pain
- dry mouth
- increased thirst
- loss of appetite or weight loss
- metallic taste
- skin rash or itching
- spinning or whirling sensation causing loss of balance
- stomach pain or upset
- trouble sleeping
- Bad, unusual, or unpleasant (after) taste and thirst
- being forgetful
- change in taste
- dryness of the skin
- hair loss
- hives or welts
- increased appetite
- red, sore eyes
- redness of the skin
- swelling or inflammation of the mouth
For Healthcare Professionals
Applies to letrozole: oral tablet
General side effects including fatigue (up to 8%), chest pain (up to 6%), peripheral edema (5%), asthenia (up to 5%), and increased weight (2%) have been reported.
Cardiovascular side effects including hypertension (up to 7%), palpitations, cardiac failure, arterial thrombosis, angioedema, and tachycardia have been reported.
Gastrointestinal side effects including nausea (up to 15%), vomiting (7%), constipation (up to 7%), diarrhea (up to 6%), abdominal pain (up to 6%), anorexia (up to 5%), dyspepsia (up to 4%), and dryness of mucosa (including dry mouth) have been reported.
In the adjuvant setting, an increase in total cholesterol in patients who had baseline values of total serum cholesterol within the normal range, and then subsequently had an increase in total serum cholesterol of 1.5 time the upper limit of normal (ULN) was 5.4% on letrozole versus 1.2% on tamoxifen. Lipid lowering medications were used by 18% of patients on letrozole and 12% on tamoxifen.
Other side effects including viral infection (up to 6%), dysesthesia, memory impairment, irritability, nervousness, stomatitis cancer pain, pyrexia, increased appetite and disturbances of taste and thirst have been reported.
Musculoskeletal side effects including musculoskeletal effects in general (up to 22%) and arthralgia (up to 8%) have been reported. Postmarketing reports have included trigger finger.
In the extended adjuvant setting, preliminary results (median duration of follow-up was 20 months) from the bone sub-study (calcium 500 mg and vitamin D 400 international units per day mandatory; bisphosphonates not allowed) demonstrated that at two years the mean decrease compared to baseline in hip bone mass density in letrozole patients was 3% versus 0.4% for placebo. The mean decrease from baseline bone mass density results for the lumbar spine at two years was letrozole 4.6% decrease and placebo 2.2%. Consideration should be given to monitoring bone mass density.
Nervous system side effects including headache (up to 12%), somnolence (up to 3%), and dizziness (up to 5%) have been reported. Postmarketing reports have included carpal tunnel syndrome.
Respiratory side effects including dyspnea (up to 9%) and coughing (up to 6%) have been reported.
Dermatologic side effects including hot flushes (up to 6%), rash (up to 5%), pruritus (up to 2%), urticaria, and dry skin have been reported.
Hepatic side effects including abnormal liver chemistries (3% in patients where it was not associated with a documented metastases) have been reported.
Hematologic side effects including leukopenia and a case of reversible pancytopenia have been reported.
Ocular side effects including cataract, eye irritation, and cases of blurred vision have been reported.
Metabolic side effects including hypercholesterolemia (3%) have been reported.
Genitourinary side effects including increased urinary frequency and vaginal discharge have been reported.
Hypersensitivity side effects including anaphylactic reactions have been reported.
More letrozole resources
- letrozole Advanced Consumer (Micromedex) - Includes Dosage Information
- letrozole MedFacts Consumer Leaflet (Wolters Kluwer)
- Letrozole Prescribing Information (FDA)
- Letrozole Professional Patient Advice (Wolters Kluwer)
- Letrozole Monograph (AHFS DI)
- Femara Consumer Overview
- Femara Prescribing Information (FDA)
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