If you have been diagnosed with hormone receptor-positive breast cancer (estrogen and progesterone), chances are your treatment plan will include surgery to remove the cancer, along with endocrine therapy and possibly other neoadjuvant or adjuvant therapies to shrink the size of your tumor before removal and/or to reduce the chance of recurrence. 

Tamoxifen (brand names: Nolvadex, Soltamox) is one type of endocrine/hormone therapy called SERMs (selective estrogen receptor modulators). 

Tamoxifen works by blocking the effects of estrogen on hormone receptors in the breast tissue. This is important, because in hormone-driven breast cancer, estrogen promotes growth of the cancer cells. If Tamoxifen is in the receptor, estrogen can’t attach to the cancer cell, meaning the cell doesn’t receive estrogen’s signals to grow and multiply.

Tamoxifen can:

• reduce the risk of breast cancer coming back by 40% to 50% in postmenopausal women and by 30% to 50% in premenopausal women,
• reduce the risk of a new cancer developing in the other breast by about 50%,
• be an effective treatment for men whose breast cancer biopsies show elevated levels of the estrogen receptor.

While on Tamoxifen, estradiol is still present in normal amounts in the body, but it cannot activate the cancer cells to grow further. If you are premenopausal at the time of your diagnosis, taking Tamoxifen will most likely cause you to experience menopause-like symptoms. This sounds scary, but the side effects are reversible after treatment. 

Tamoxifen & Your Period

Fun fact: Tamoxifen was originally created as a contraceptive pill. Scientists in the 1960s synthesized the drug, hoping it would block estrogen and act as an effective contraceptive. However, during testing, they found that Tamoxifen stimulated, rather than suppressed, ovulation.

If you are still having regular periods when you start taking Tamoxifen, you may find that your period changes. For instance, your period may become lighter, less frequent, or may stop altogether. 

Whilst a complete loss of the menstrual cycle can occur while taking Tamoxifen, take comfort in knowing that Tamoxifen does not induce menopause, and may not indicate menopause. Some women will even continue to have normal periods while taking Tamoxifen.

And ladies, it's important to know that it's still possible to become pregnant while taking tamoxifen — even if your periods have become less regular or have stopped altogether — because Tamoxifen may be harmful to a developing baby. So it's important to use a non-hormonal method of contraception if you are sexually active while taking Tamoxifen and for two months after stopping. Some examples of non-hormonal methods of contraception include diaphragms, condoms and femidoms.

How long will I have to take Tamoxifen?

Early stage cancers are generally prescribed 5 years of Tamoxifen, while later stages, or those with a high risk of recurrence, will be put on a 10-year plan (this applies to both women and men with breast cancer). Most physicians require female patients to be on Tamoxifen for 18 months before taking a break to carry a pregnancy (yes, this is possible!) and recommend that they return to the regimen to complete the full prescribed term afterward.  Note that studies have shown no increase in a risk of recurrence or death by making this choice.  Sigh of relief.  

Menopausal symptoms sound terrible, what should I expect?  

Tamoxifen comes with a long list of potential side effects, but take comfort in knowing you won’t experience all of them!  Your body’s response is unique and some people tolerate the drug with few side effects, if any.  

Below are the most common side effects and some mitigation tips that we’ve picked up along the way through our own patient journeys. As always, be vocal with your team about what you are experiencing, ask them if any of these possible remedies are right for you. 

1. Hot Flashes

The hot flashes can be intense at the start (in my case, they were literally every hour, which can be pretty disruptive day and night) but they will dissipate over time.  Some strategies to calm those down are:

• Avoid caffeine/alcohol & triggering foods:  Yes, this is a drag, but alcohol, caffeine and certain foods can make your side effects worse. Pay attention to the foods that trigger your flashes.  It doesn’t mean you have to skip them altogether, but you will find if you lessen the frequency of the trigger, fewer flashes = happier you! And chances are you’re already avoiding or reducing your alcohol consumption, so here’s one more reason to do so. Some things that triggered hot flashes for me personally are black tea, some brands of drip coffee, soy sauce, white wine, the combination of kale/chicken and sometimes even chia seeds! 

• Wear layers: day and night! In periods of frequent flashes, I found that stress of any kind would trigger a flash. This can be awkward while working in an office (or giving a video presentation), so dress in layers!  If you feel a flash coming on, take off a layer — quickly! If you have a big meeting, avoid caffeine beforehand. Keep a cooling mist handy; a water spray bottle can work too. At night, wear breathable fabrics (cotton or silk) and change bedding to lighter weight options like bamboo sheets, down alternative comforters and temperature- regulating materials.  I also found that hugging a pillow (or person) can generate so much heat that it triggers the flash. If you feel a flash coming on, let go or remove the pillow/blanket.  Or not. If Tamoxifen hot flashes are keeping you up at night, try taking it in the morning instead.

• Climate control: if possible, keep temperatures on the cooler side in your work and sleeping spaces (68 degrees is ideal).

• Ice packs:  these can be a savior if you apply to your neck or chest when feeling a flash coming on — try stashing one in your pillowcase at night to stay cool.

• Supplements: Swedish bee pollen extract, evening primrose oil and black cohosh have been shown to provide relief in some patients. Note that while some studies have supported the use of black cohosh while on Tamoxifen without interference, and possibly even enhance the drug, most studies are uncertain. And some studies show that evening primrose oil enhances the function of Tamoxifen, but may increase the risk of bleeding issues - especially in those with liver problems or who are taking blood thinners. As always, discuss taking any supplement with your provider or team before trying it to ensure it's right for you.  

• Antidepressants & other prescription medications: some antidepressants (such as Effexor) have been shown to reduce hot flashes.  Work with your physician to understand which antidepressant could be right for you. A new non-hormonal medication, called Veozah, was approved by the FDA in mid-2023, for the relief of vasomotor symptoms in menopausal women.  However, it does have some hormonal effects and has not been studied in women with breast cancer. Some medications interact with Tamoxifen, so check with your medical professional before starting anything new. 

• Acupuncture: has been known to help decrease hot flashes, but must be done consistently for at least 6 weeks to be effective.

• Exercise. Light to moderate daily exercise can do wonders for your state of mind, reducing anxiety and also helping to lessen the duration of your hot flashes!  Exercises like yoga with breath work, meditation, walking and taking the stairs are all great ways to start or to incorporate into your routine. Regular aerobic and resistance training are recommended during and after treatment so don’t be shy about it! If you don’t work out regularly, be mindful to ease into any new exercise program gradually as strenuous exercise can trigger hot flashes in unconditioned women. If possible, work with a physical trainer or therapist who can create a program just for you.  Many cancer hospitals have free exercise programs, so inquire with your treatment team what may be available to you.  You got this.

2. Stiff Joints & Tight Muscles

Regular exercise (even just walking) and yoga help immensely.  Also, studies have shown that at least 2.5 to 5 hours of moderate-intensity physical activity or 1.25 to 2.5 hours of vigorous-intensity aerobic physical activity per week can lead to a 55% reduced chance of cancer recurrence. Just keep moving! Also, eating an anti-inflammatory diet and taking Omega-3 (fish oil) can help with joint and muscle mobility. Check with your doctor before starting any new supplement for the correct dosage and potential interactions.

3. Dehydration & Muscle Cramps

While taking Tamoxifen, you will need to increase your fluid consumption and eat more foods with high water content (like fruits and vegetables) to stay hydrated.  Potassium-rich foods such as bananas, dried apricots, cooked spinach, raw avocados, cantaloupe, nectarines and plain yogurt can help with muscle cramps. Magnesium citrate can help too.  I always know when I’m low on electrolytes, as I get cramps in my feet and back.  

4. Accelerated Aging

This one hurts the ego, but yes, it does accelerate the onset of wrinkles and gray hair. I’ve mostly noticed a decrease in elasticity of my skin and some more grays, but I’ve also been on T for 4 years so it’s likely a combination of that and the natural aging process. One option to help restore your body’s collagen and elastin, is the supplement Biosil. I used this during chemotherapy and felt it really helped with my skin, hair and nails. You can also support collagen production through your diet by getting adequate intake of foods that contain vitamin C, zinc, copper and manganese. These nutrients can be found by eating a varied diet rich in fruits and vegetables, including green leafy, root vegetables, nuts and seeds — especially hemp, pumpkin and cashews. Staying hydrated helps keep the skin looking plump and more youthful too. Lastly, if a quick fix is in order, there’s always botox and fillers to be explored. Be sure to work with a licensed dermatologist, plastic surgeon or physician's assistant, who can tailor a plan to your unique needs - and double check with your oncologist that the timing is right.

5. Hair Loss or Thinning

Some people experience thinning of the hair or endocrine therapy-related alopecia. There’s a clinical trial underway lead by onco-dermatologist, Dr. Anthony Rossi, whereby Platelet Rich Plasma injections in the scalp are used to promote hair regrowth during treatment.  Supplements such as Biotin, Nutrafol, and many others can also help; always check with your physician and/or cancer nutritionist for interactions before trying anything new. 

6. Weight Changes

Some women experience weight gain right away, others don’t.  Most patients notice a redistribution of weight and more stubborn fat around the stomach area, which is known in patient communities as “tamoxifen belly.”  Some women experience weight gain several years into treatment. As this happens, many women find success in reducing their carbohydrate intake and amending their fitness routines to include more resistance training and Pilates over cardio.  Tamoxifen can sometimes cause fluid retention as well, which can affect weight. Avoid/reduce salty or processed foods, elevate the swollen area, avoid standing for long periods of time if having ankle or leg swelling, and elevate head whilst sleeping to help with eye swelling.

7. Diminished Libido & Vaginal Dryness:

Perhaps one of the most challenging side effects for women on Tamoxifen (and other cancer treatments) and their partners is the loss of libido and increase in vaginal dryness that come with blocking estrogen in the cells of the vaginal lining, causing it to become thinner and weaker and leading to dryness, discharge, and itchiness. There are a few things to try for this: 

• Lubricants: coconut oil is a great natural option, or aloe-based formulas like Aloe Cadabra

• Daily vaginal lotions: such as Kindra, Créme de la femme, Replens and soothing bath soaks

• Suppositories: Revaree, KY liquibeads (these last several days)

• Sex therapy: your oncology team may refer you to a sex therapist for a consultation. This could include physical therapy (yup, this means using vaginal dilators), relationship therapy, or both. If possible, work with a specialist who’s trained in helping cancer patients and survivors.

Note: Tamoxifen can affect the lining of the uterus (endometrium) which may become thickened. If you have unexpected vaginal bleeding or pain, tell your treatment team and/or gynecologist.

Vaginal Atrophy

Can occur and will cause pain with intercourse and dryness in the area. One option offered by OB/GYN practices is laser resurfacing with a procedure called the Mona Lisa touch.  This requires multiple treatments and maintenance and is not covered by insurance, making it inaccessible to some. Estrogen suppositories (estradiol) at low doses can sometimes safely be used in patients with hormone positive cancers, as it stays local within the tissues and doesn’t circulate in the bloodstream.  This approach may be preferred by your oncologist over the Mona Lisa touch, which is not FDA-approved for the treatment of vaginal atrophy in cancer patients (as of the time of this article). Plus, there is more data on the use of estradiol vs. fractional CO2 therapy in breast cancer patients. However, a clinical trial published in 2022 has indicated sustained improvement in sexual function with fractional CO2 laser therapy.  Discuss your individual risk factors with your oncologist to determine if either therapy could be an option for you.

8. Bone Density

Tamoxifen is known to reduce bone density in premenopausal women and you will be tested yearly while on this medication.  Strategies to keep this to a minimum — and minimizing the risk of osteoporosis — are weight-bearing exercise (lifting weights in particular), calcium supplementation and eating calcium-rich foods (like dark leafy greens, bok choy, salmon and certain beans).  However, in postmenopausal women, Tamoxifen can decrease or slow down bone loss. 

9. Constipation

While there can be many sources of constipation, Tamoxifen doesn’t help the issue.  Some options to try are drinking plenty of water, getting enough fiber, using probiotics, taking magnesium citrate, getting regular exercise, and giving yourself ample time to go.  If you suspect you have a gut imbalance, try working with a GI specialist or Functional Medicine doctor who specializes in gut health and can test you for food sensitivities, a candida imbalance or leaky gut. Always consult with your cancer center nutritionist before taking any supplements prescribed by a non-cancer specialist.  

10. Fatigue

Tamoxifen can cause an extreme feeling of lack of energy or weakness that doesn’t improve with sleep. Some helpful strategies to address this are: 

• Get regular, moderate exercise 

• Keep a food journal to determine patterns of energy levels and your dietary choices. 

• Make time in your schedule to rest or take naps throughout the day (with a half-hour time limit, to avoid disturbing your sleep cycle)

• Keep to a regular sleep routine.

• Plan your work schedule around the most important things, in case you don’t have energy to fulfill all of your daily tasks.

Does it matter which brand of Tamoxifen I take?

Generally, it does not matter which brand your pharmacy prescribes (the two main brand names in the U.S. are Nolvadex and Soltamox). However, some side effects can be better managed or even eliminated by switching brands or the dosage; so before you give up, ask your physician if which of the two options is recommended for you.

Note that Raloxifene and Fareston are the two other drugs in the SERM category that your doctor may prefer based on your unique risk factors (premenopausal vs. postmenopausal, osteoporosis risk, and your cancer staging).  Ask always, ask your doctor about the pros and cons of each for your individual scenario.

Precautions & Drug Interactions

It's important to be aware of the foods and medications that could interfere with the effectiveness of Tamoxifen in your system. 

• Grapefruit: other citrus fruits are fine, but grapefruit is known to interfere with the effectiveness of Tamoxifen and should be avoided. 
• Benadryl
• Certain antidepressants

A helpful resource to double-check potential interactions can be found here.

The Breast Cancer Index Test

For those of you on the 10-year plan, there’s an exciting development that you’ll want to know about.  At the 5-year mark, you can take a test called The Breast Cancer Index  that provides your individual risk of recurrence percentage and indicate whether 5 more years of hormonal therapy will improve your outcome. If not, you may be eligible to complete your Tamoxifen course early.  Now doesn’t that sound liberating!   

You will have many seasons during your Tamoxifen journey, and some women opt out of treatment early for quality of life concerns. However, your chances of mitigating recurrence is much greater if you stay on the medication. Hopefully this article inspires you to try new things — and, as always, to advocate for yourself with your team!