Knowing the potential interactions between tamoxifen and antidepressants is important if you are taking these types of medications. Not all antidepressants have this interaction and can be safe to use along with tamoxifen.
This article will review the use of tamoxifen, the potential interactions with antidepressants, and which ones may be safer to take.
Why Tamoxifen Is Used
Once the initial treatment of breast cancer is completed—which may involve therapies such as surgery, chemotherapy, and radiation therapy—taking hormonal therapy may be recommended. If your tumor is estrogen-receptor positive, hormone therapy can reduce the risk of cancer coming back.
For those people who are premenopausal, tamoxifen is usually the medication used. For those who are postmenopausal or who are premenopausal but have received ovarian suppression therapy, an aromatase inhibitor is usually used instead.
Estrogen-receptor positive breast cancer cells are fueled by estrogen that naturally occurs in the body. Estrogen attaches to these cancer cells and aids in their growth.
Tamoxifen works by binding itself to these receptors so that estrogen can’t, essentially starving the cancer cells of their food.
The side effects of tamoxifen include menopausal-type symptoms such as hot flashes, low sex drive, and vaginal dryness. It has been found that some antidepressant medications can reduce these symptoms, as well as treat depression that may accompany breast cancer.
However, combining antidepressants and tamoxifen can lead to problems of its own, which healthcare providers discovered after antidepressant treatment became commonplace in women with breast cancer.
Interaction Concerns
In your body, tamoxifen is broken down as it is digested and turns into endoxifen. Endoxifen is stronger than tamoxifen and is responsible for most of the clinical effects. The pathway in which tamoxifen is broken down is through something called the cytochrome P450 enzyme CYP2D6.
Any drugs that reduce the activity of the CYP2D6 enzyme—and there are many—can reduce this breakdown process and prevent endoxifen from being produced. This, of course, means that your tamoxifen treatment may not work as intended—or, perhaps, at all.
Interactions between tamoxifen and other drugs are common, and this includes many medications in addition to antidepressants. Since many of these are commonly used drugs, it’s important to talk to your healthcare provider and pharmacist about any medication, over-the-counter preparation, or dietary supplement you are considering while you are on tamoxifen.
Since many people take tamoxifen for five to 10 years, this is even more important. Keep in mind that not all healthcare providers are familiar with these interactions. What this means is that if you should go to urgent care with an infection, for example, talk to your oncologist or pharmacist before taking any medications that have been prescribed during that visit.
Antidepressants and Their Risk
It has been found that some classes of antidepressants are more likely to interfere with tamoxifen than others. Medications that are strong CYP2D inhibitors, such as Prozac (fluoxetine) and Paxil (paroxetine), interfere with the conversion of tamoxifen to endoxifen, decreasing the ability of the drug to prevent cancer recurrence.
With other antidepressants, there is a moderate interaction, and with others, only a slight one. Meanwhile, some supplements believed to help alleviate depression can interact with tamoxifen as well.
The below table summarizes what we know about several antidepressants and supplements thus far.
Antidepressants such as Paxil or Prozac should be avoided, while others, such as Celexa or Lexapro, may be a safer option.
A Word From Verywell
If you are considering an antidepressant medication, have a careful discussion with your healthcare provider. Also, periodically ask if anything has changed regarding the current understanding of potential interactions with your tamoxifen, as this is an area of active research.
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