Is Tamoxifen Chemotherapy? Plus 4 More Tamoxifen FAQs

Breast cancer is the second most common cancer among U.S. women. And there are many treatments available. Tamoxifen is a common treatment option for people with estrogen receptor-positive (ER+) breast cancer.

It can be overwhelming to be prescribed any breast cancer treatment, and it’s understandable to have questions. While your healthcare provider has likely reviewed the basics, you may find yourself thinking of more questions after your appointment is over.

Here, we’ll answer five frequently asked questions about tamoxifen, from whether it’s considered chemotherapy to how long you might take it.

1. Is tamoxifen chemotherapy?

No, tamoxifen is not chemotherapy. Tamoxifen is a type of hormone therapy. These two cancer treatments work differently.

Chemotherapy (“chemo”) works by killing rapidly dividing cells. Cancer cells divide faster than normal cells, which can lead to tumors. Chemotherapy targets these rapidly dividing cells and can help shrink tumors.

Hormone (endocrine) therapy lowers the amount or activity of certain hormones in the body, such as estrogen and progesterone. These hormones can act as fuel for certain types of cancer cells, helping them to grow. By lowering the amount or activity of hormones, these treatments cut off some of that supply feeding cancer cells.

How does tamoxifen work in the body?

Tamoxifen belongs to a group of medications called selective estrogen receptor modulators (SERMs). These medications impact estrogen’s effects in different areas of the body — either by activating or blocking them.

In some areas of the body, certain SERMs block estrogen from attaching to its receptors (binding sites). By blocking this attachment, SERMs lower estrogen’s activity in those areas. Notably, tamoxifen blocks estrogen receptors in the breast where cancer cells are growing.

In other areas of the body, such as the uterus and bones, tamoxifen can activate estrogen receptors. This increased activity can have potential benefits, such as bone protection for postmenopausal women. But it can also have risks, such as an increased risk of uterine cancer.

2. What’s the typical dose of tamoxifen?

Tamoxifen comes as an oral tablet and oral liquid (called Soltamox). The dosage depends on how advanced your breast cancer is. But most people take 20 mg by mouth per day. You can tamoxifen with or without food.

If you’re taking 20 mg per day or less, you’ll likely take a once-daily dose. If you’re taking more than 20 mg per day, your healthcare provider may recommend that you split your daily dose into two smaller doses. You’d take these smaller doses twice a day.

3. How long does tamoxifen stay in your system?

Tamoxifen can stay in your system for quite a while. In fact, it takes the body about 2 months to clear the medication from your system.

This information is important to keep in mind if you’d like to become pregnant. Tamoxifen can cause birth defects and shouldn’t be taken if you're pregnant. So you should wait at least 2 months after finishing the medication to try to become pregnant. If you become pregnant while taking tamoxifen, contact your healthcare provider right away.

4. How long do you have to take tamoxifen?

Most people take tamoxifen for at least 5 years. This includes taking it for breast cancer treatment or prevention. Some experts recommend taking tamoxifen for up to 10 years. This extended length of treatment can help to prevent breast cancer from returning (also called recurrence).

However, some studies have found that women with certain types of early-stage breast cancer may not need to take tamoxifen for quite as long. Some evidence supports taking low-dose tamoxifen (5 mg a day) for 3 years. This option isn’t right for everyone, though. Your healthcare provider will suggest the best treatment length for you based on your personal needs.

5. Does tamoxifen cause menopause?

Tamoxifen is unlikely to cause menopause. But menopause symptoms, such as hot flashes and vaginal dryness, are common tamoxifen side effects. You may also notice your period become irregular or disappear altogether. The side effects are typically reversible once you stop taking tamoxifen.

However, most people are diagnosed with breast cancer after age 50. So it’s common for people taking tamoxifen to experience natural menopause while they’re taking the medication. And other treatments you may have received, such as chemotherapy, can cause menopause to start earlier.

How to save on tamoxifen

There are ways to save on tamoxifen, which is available as both a brand-name and generic medication.

• Save with GoodRx. GoodRx can help you save over 90% off the average retail price of the generic version. Generic tamoxifen’s price at certain pharmacies is as low as $42.04 with a free GoodRx discount.

• Save with a copay savings card. If you have commercial insurance and meet eligibility requirements, Soltamox’s price may be as little as $0 using a savings card from the manufacturer.

• Save with patient assistance programs. If you’re uninsured or underinsured, you may be eligible for patient assistance programs for Soltamox, which offer the medication free of cost.

Why trust our experts?

Written by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Our editorial standards

Meet our experts