You probably already know that taking tamoxifen (sold as Soltamox) can cause hot flashes or make you feel too warm. But some MyBCTeam members have commented that, instead, they feel chilled all the time. One member asked, “Anyone who’s on tamoxifen just feel cold?”

Another member who takes tamoxifen replied, “I get really cold and mentioned these symptoms to the oncologist, and they told me they were typical.” Despite having chills and feeling cold being fairly common among people taking tamoxifen for breast cancer, there hasn’t been much research on this effect.

If you take tamoxifen and have noticed that you feel cold, you’re not alone. Read on to learn more about how this medication may affect temperature sensations in some people.

🗳️ Have you noticed changes in how you feel temperature since being on tamoxifen?

Yes, I feel hot flashes.

Yes, I feel cold flashes.

Yes, I feel both hot and cold flashes.

No, I haven’t noticed changes in how I feel temperature.

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What Causes Chills?

If you feel an unexplained chill, it usually means that your body’s attempting to stay at the right temperature. When you’re too cold, your body sends signals to your muscles to contract and relax to generate more heat. This process is called thermoregulation.

Factors that can affect body heat include:

• Room temperature — Your body needs more energy to keep you warm when the air is cooler.
• Food — Eating gives you the energy to maintain your internal temperature.
• Exercise — You may feel warm during a workout but cooler as your sweat dries.
• Age — Your body temperature typically lowers as you get older.

Other common causes of chills include:

• Bacterial infections, such as pneumonia and urinary tract infections
• Viruses, such as influenza
• Hangover from excessive alcohol intake
• Low blood sugar
• Night sweats or hot flashes due to menopause or hormonal changes
• Panic attacks
• Parasitic infections, such as giardiasis
• Sepsis

Breast cancer survivors often feel uncomfortable — either too hot or too cold — at temperatures that others consider ideal. If you are living with breast cancer or undergoing cancer treatment, you may feel chills for a variety of possible reasons. Your chills may result from infection, hormonal changes, treatment effects, or an unrelated medical issue.

Are Chills a Common Side Effect of Tamoxifen?

Tamoxifen is a hormone therapy used to treat several types of hormone receptor-positive breast cancer. Manufacturers of tamoxifen do not list chills as one of the medication’s side effects.

The most common side effects of tamoxifen include:

• Hot flashes (also known as hot flushes)
• Fatigue
• Vaginal discharge or loss of libido
• Skin and hair changes, such as dry skin, skin rash, and hair thinning or loss
• Weight gain
• Mood changes, including depression
• Constipation
• Joint pain

Less common but potentially serious side effects include:

• Life-threatening blood clots in the lungs or lower legs
• Liver problems
• Anemia (low red blood cell count)
• Blurred vision or other symptoms of cataracts
• Stroke
• Unusual vaginal bleeding

How Could Tamoxifen Cause Chills?

Despite chills not being listed as a side effect of tamoxifen, MyBCTeam members often mentioned them. “I’ll feel cold, like I just can’t get warm. Then I get really warm. I’ve been on tamoxifen for almost three years,” one member said.

If you take tamoxifen and experience chills, it could be due to changes in your hormones. Tamoxifen is a selective estrogen receptor modulator that blocks estrogen. As a result, many people experience side effects similar to those of menopause, especially hot flashes and sweating.

Hot flashes are often followed by chills as your sweat dries and you lose heat through your skin. A MyBCTeam member described their experience like this: “I had cold flashes and hot flashes — I went from one extreme to the other.”

Could Breast Cancer Lead to Chills?

Breast cancer treatment — and the disease itself — may also cause chills. “I have a hard time feeling normally warm. I have a duvet and a thick fleece blanket on top and a hot water bottle in bed. Brrrr!” shared a MyBCTeam member.

Most medical research on temperature regulation in breast cancer survivors focuses on feeling too hot from menopause-like symptoms and medication side effects. Although there isn’t as much research on why survivors may feel cold, several factors could come into play.

Fatigue

Your body uses a lot of energy to keep you warm. If you’re tired from breast cancer or its treatment, that could affect your ability to maintain your internal temperature.

Fatigue caused by breast cancer or its treatment can reduce the amount of energy available to your body to keep warm. Additionally, there’s evidence that breast cancer might disrupt the internal clock that regulates your body temperature based on the time of day.

Infection

When your body starts to fight off an infection, you may experience chills. Some breast cancer treatments, such as chemotherapy and targeted therapy, can make you more prone to infection.

These treatments, sometimes used alongside tamoxifen, can reduce your number of white blood cells. White blood cells help the body fight infections. Having lower levels of white blood cells increases your risk of infection.

Chills with fever during chemotherapy or another immune-suppressing treatment can be a warning sign of serious infection. In this case, reach out to your doctor right away.

Loss of Appetite

If you aren’t eating enough because the side effects of your breast cancer treatment cause a loss of appetite, you may have less energy available in your body to keep you warm.

Join the Conversation

On MyBCTeam, people share their experiences with breast cancer, get advice, and find support from others who understand.

Have you experienced chills while taking tamoxifen or other breast cancer treatments? Let others know in the comments below.