What side effects are possible with this medication?
A side effect is an unwanted response to a medication when it is taken in normal doses. A side effect may be mild or severe, temporary or permanent, but does not occur in everyone. 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 over time. If you develop any of these side effects (or any other side effects not listed here) or they change in intensity, speak to your doctor or pharmacist for advice on managing them and on the risks and benefits of the medication.
- dizziness
- headache
- hot flushes
- increased sweating
- pain in muscles, bones, or joints
- signs of a blood clot in the arm, leg (tenderness, pain, swelling, warmth, or redness in the arm or leg), or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
- swelling or puffiness due to retained body fluid
- trouble sleeping
- weakness
- vaginal dryness or irritation
Click here to learn about serious side effects that can potentially occur with any medication. These examples are provided for information purposes only and are not meant to be exhaustive. Always consult your doctor for sound medical advice specific to your particular medication and treatment.
Are there any other precautions or warnings for 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.
Bone mineral density: Long-term use of letrozole may decrease the density of bones, increasing the risk of osteoporosis. Bone mineral density should be monitored regularly while taking letrozole.
Cholesterol: Letrozole may increase cholesterol levels. Regular monitoring of cholesterol levels is recommended.
Drowsiness/dizziness: Letrozole may cause dizziness or drowsiness. People who experience either or both of these side effects should not drive, use machinery, or perform any other activities that require alertness.
Kidney disease: Since there is limited experience with the use of letrozole by people with severe kidney function impairment, the risks and benefits of using letrozole should be considered carefully.
Liver disease: People with severe liver disease who take this medication should be closely monitored by their doctor.
Premenopausal women: Letrozole should not be used by women who have not reached menopause unless the potential benefits outweigh the risks.
Pregnancy: Letrozole has not been studied for use by pregnant women, since it is intended only for women past menopause. However, it is suspected that its use during pregnancy could cause miscarriages and other serious problems. Therefore, this medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if letrozole passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of this medication have not been established for children.
What other drugs could interact with this medication?
There may be an interaction between letrozole and any of the following:
- any estrogen-containing medications
- tamoxifen
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.