Search Content

Letrozole

Precautions

Before taking letrozole, tell your doctor or pharmacist if you are allergic to it; or to anastrozole; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: high blood fats (cholesterol), bone problems (such as osteopenia, osteoporosis), stroke or blood clots, heart disease (such as chest pain, heart attack, heart failure), high blood pressure, kidney problems, liver problems.

This drug may make you dizzy or tired or rarely blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or tired. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This medication must not be used during pregnancy. It may harm an unborn baby. Letrozole is used mainly in women after menopause. If you have recently gone through menopause, discuss the need for use of reliable forms of birth control while taking this medication and for 3 weeks after stopping treatment with your doctor. Do not use birth control products containing estrogen. Consult your doctor for more details. If you become pregnant or think you may be pregnant, tell your doctor right away. (See also How to Use section.)

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug and for at least 3 weeks after the last dose. Consult your doctor before breastfeeding.

Side Effects

Hot flashes, hair loss, bone pain, tiredness, unusual sweating, nausea, diarrhea, dizziness, and trouble sleeping may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: nausea/vomiting that doesn't stop, bone fractures, pain/swelling of the joint/muscle/tendon, mental/mood changes (such as depression, anxiety), swelling of arms/legs, blurred vision, unusual tiredness, dark urine, yellowing eyes/skin..

This medication (and cancer) may rarely cause serious problems from blood clots (such as heart attack, stroke, blood clots in the lungs or legs). Get medical help right away if you experience: shortness of breath/rapid breathing, chest/jaw/left arm pain, confusion, sudden dizziness/fainting, pain/swelling/warmth in the groin/calf, trouble speaking, weakness on one side of the body, sudden vision changes, sudden/severe headaches, unusual sweating.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat/neck), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

RxAnswers™ is a copyrighted combined product from TraceGains and First DataBank, Inc.

Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.

This information is intended only for residents of the United States. Products sold under the same brand names in other countries may contain different ingredients.

Learn more about First DataBank

There are some limitations on the information provided in “Nutrient Interactions.” Do NOT rely solely on the information in this article. Please read the disclaimer.

Learn more about TraceGains, the company.

TraceGains and/or its suppliers make no warranties or representations as to the accuracy or completeness of this content herein or that of any organization referred or linked to within this content and will not be liable for any damages arising out of your access to or use of any information found herein or that of any organization referred to within this content.

Information expires December 2025.