Femara interactions: Alcohol, medications, and other factors

Femara (letrozole) is a brand-name oral tablet prescribed for treating certain types of breast cancer. Femara has interactions with some other drugs, such as tamoxifen (Soltamox), and DHEA supplements.
An interaction occurs when one substance causes another substance to have a different effect than expected.
interaction
To learn more about Femara’s interactions, keep reading. For additional information about Femara, including details about its uses, see this article.
this article
Femara interactions with other medications  
Before you start treatment with Femara, tell your doctor and pharmacist which prescription, over-the-counter, and other medications you take. By sharing this information with them, you may help prevent possible interactions. (To learn whether Femara interacts with supplements, herbs, or vitamins, see the “Femara and other interactions” section below.)
If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.
Here’s a table of drugs that can interact with Femara. Keep in mind that this table doesn’t include all drugs that may interact with Femara. Some of these interactions are described in detail just below in “Drug interactions in depth.”
tamoxifen
When to avoid Femara
In some cases, factors or conditions could prevent your doctor from prescribing Femara due to the risk of harm. These are known as contraindications. The contraindications of Femara include:
Doctors typically will not prescribe Femara during pregnancy. This is because Femara may cause harm to a fetus if the drug is taken during pregnancy.
For breast cancer during pregnancy, your doctor can recommend a different treatment option. If you’re able to become pregnant, your doctor can advise you on birth control options to use while taking Femara. They’re also likely to recommend continuing the use of birth control for at least 3 weeks after your last dose of Femara.
breast cancer during pregnancy
birth control
If you have questions about Femara and pregnancy, talk with your doctor.
If you have had an allergic reaction to Femara or any of its ingredients, your doctor will likely not prescribe Femara. Taking the drug could cause another allergic reaction. You can ask them about other treatments that may be better choices for you.
allergic reaction
Note: Before you start treatment with Femara, it’s important to tell your doctor if these contraindications apply to you. They can determine whether to prescribe Femara.
Femara and alcohol
There aren’t any known interactions between Femara and alcohol.
alcohol
However, Femara and alcohol may cause similar side effects. For example, both can cause nausea, fatigue, or dizziness. If you consume alcohol during Femara treatment, these side effects could be more likely to occur.
fatigue
If you have questions about drinking alcohol during Femara treatment, talk with your doctor.
Drug interactions in depth
Here’s a closer look at certain drug interactions of Femara.
Estrogen (Menest, Premarin) is prescribed as hormone replacement therapy for menopause and for other uses.
hormone replacement therapy
Interaction result: Taking Femara with estrogen can make Femara less effective.
Interaction explained: Femara works to treat breast cancer by reducing the amount of estrogen your body makes. Combining the drug with estrogen could counteract the estrogen-lowering effect of Femara.
breast cancer
estrogen
Taking estrogen could also promote the growth of breast cancer, which could make Femara less effective.
Steps you or your doctor may take: Your doctor is unlikely to prescribe Femara with estrogen. They can suggest alternative treatments to either drug.
To learn more about Femara and estrogen, talk with your doctor or pharmacist.
Prasterone (Intrarosa) is prescribed to treat painful sex that occurs after menopause.
after menopause
Interaction result: Taking Femara with prasterone can make either drug less effective.
Interaction explained: Femara lowers estrogen levels in the body. Prasterone increases the level of certain hormones, including estrogen. Taking these drugs together could make Femara or prasterone less effective.
Steps you or your doctor may take: Your doctor is not likely to prescribe Femara with prasterone. They can tell you about possible treatment alternatives to either drug.
To learn more about Femara and prasterone, talk with your doctor or pharmacist.
Both Femara and tamoxifen (Soltamox) are prescribed to treat breast cancer.
tamoxifen
Interaction result: Taking Femara with tamoxifen can make Femara less effective.
Interaction explained: If you take these drugs together, tamoxifen may lower the level of Femara in your body. Having a low level of Femara may decrease the effectiveness of the drug.
Steps you or your doctor may take: Your doctor may not prescribe Femara with tamoxifen. However, Femara can be prescribed for certain breast cancers that have been treated with tamoxifen in the past.
To learn more about Femara and tamoxifen, talk with your doctor or pharmacist.
Femara and other interactions
Femara may have other interactions, such as with supplements, foods, vaccines, or even lab tests. You’ll find details below. Keep in mind that the following information does not include all other possible interactions with Femara.
Femara may interact with dehydroepiandrosterone (DHEA) supplements. Some people take this supplement for vaginal atrophy and other conditions. Taking a DHEA supplement during Femara treatment could decrease the effectiveness of both products.
dehydroepiandrosterone (DHEA)
vaginal atrophy
Your doctor may be able to suggest an alternative to DHEA supplements.
Before you start treatment with Femara, tell your doctor and pharmacist which supplements, herbs, and vitamins you take. By sharing this information with them, you may help prevent possible interactions.
supplements, herbs, and vitamins
If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.
There are no reports of herbs interacting with Femara. However, that doesn’t mean herbal interactions won’t occur or be recognized in the future. Because of this, it’s important to check with your doctor or pharmacist before taking any of these products during Femara treatment.
reports
There are no reports of vitamins interacting with Femara. However, that doesn’t mean vitamin interactions won’t occur or be recognized in the future. Because of this, you should talk with your doctor or pharmacist before taking any vitamin product with Femara.
reports
There are no reports of food interactions with Femara. If you’d like to learn more about eating certain foods during treatment with Femara, talk with your doctor.
reports
There are no reports of vaccine interactions with Femara. Talk with your doctor or pharmacist to see whether you’re due for any vaccines.
reports
vaccines
A decreased lymphocyte count was reported in some people taking Femara in clinical trials. If you have concerns about this medication interacting with lab tests, talk with your doctor.
lymphocyte count
reported
Cannabis (often called marijuana) and cannabis products, such as cannabidiol (CBD), have not been reported to interact with Femara. However, as with any drug or supplement, talk with your doctor before using cannabis in combination with Femara. The impact of cannabis may affect how well you stick to your Femara treatment plan.Note: Cannabis is illegal at a federal level but is legal in many states to varying degrees.
Cannabis
reported
Femara and health-related interactions
Certain medical conditions and other factors may increase the risk of interactions with Femara. Before you take this drug, be sure to talk with your doctor about your health history. Femara may not be the right treatment option if you have certain medical conditions or other factors affecting your health.
Health conditions or factors that might interact with Femara include:
Liver problems: Before taking Femara, tell your doctor if you have a liver problem such as liver failure. Having a liver problem could raise the level of Femara in your body and increase your risk of side effects. To help reduce this risk, your doctor may prescribe a lower Femara dosage than is typical.
liver failure
side effects
Femara dosage
Osteoporosis: Before starting Femara treatment, tell your doctor if you have osteoporosis. Femara may weaken your bones, which could worsen this condition. Your doctor can advise you on whether Femara is a safe treatment option.
osteoporosis
High cholesterol: Before taking Femara, tell your doctor if you have high cholesterol. The drug could increase your cholesterol levels, which could worsen this condition. Your doctor can recommend whether Femara is a safe treatment option.
high cholesterol
Allergic reaction: If you’ve had an allergic reaction to Femara or any of its ingredients, your doctor will likely not prescribe Femara. Taking the drug could cause another allergic reaction. You can ask them about other treatments that may be better choices for you.
allergic reaction
Breastfeeding: It’s not known whether it’s safe to take Femara while breastfeeding or whether the drug passes into breast milk. Due to the risk of serious side effects, breastfeeding is not recommended during Femara treatment or for at least 3 weeks after your last dose. If you’re breastfeeding or planning to, talk with your doctor before taking Femara. They can talk with you about treatment options and ways to feed your child.
Pregnancy: Doctors typically will not prescribe Femara during pregnancy. For details, see the “When to avoid Femara” section.
Preventing interactions
You can take certain steps to help prevent interactions with Femara. Your doctor and pharmacist are key resources, so reach out to them before starting treatment. For example, you should plan to do the following:
Let them know if you drink alcohol or use cannabis.
Tell them about any other medications you take, as well as any supplements, herbs, and vitamins.
Create a medication list, which your doctor and pharmacist can help you fill out.
medication list
It’s also important to read the Femara label and other paperwork that may come with the drug. The label may have colored stickers that mention an interaction. And the paperwork, sometimes called the medication guide or patient package insert, may contain details about interactions.
paperwork
If Femara doesn’t come with paperwork, you can ask your pharmacist to print a copy. If you need help reading or understanding this information, ask your doctor or pharmacist.
You can also help prevent interactions with Femara by taking it exactly as your doctor prescribes.
Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.