When you’re living with breast cancer, any new symptom can be worrying. A metallic taste, sleep problems, or vaginal changes may make you wonder if your cancer is coming back.

“I keep getting a bad taste in my mouth,” wrote a member of MyBCTeam who’d been taking tamoxifen (Soltamox) for two months. “I can’t find anything online about tamoxifen impacting taste, so of course, now I am paranoid that some other cancer exists since what I keep finding is that this could be a sign of cancer.”

In most cases, health changes are caused by breast cancer treatment side effects. Medications like tamoxifen can help treat hormone receptor-positive breast cancer, but they can also cause a wide range of side effects.

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Some tamoxifen side effects happen in more than 10 percent of people who take it. Knowing what to expect can help you feel more prepared and less alarmed when they happen.

Tamoxifen-related taste changes aren’t as common as some other side effects, but they still affect many people, including some members of MyBCTeam.

“I have a salty taste in my mouth every single day,” wrote one member. “I am positive it is from tamoxifen. I don’t take any other meds.”

You may notice a metallic or bitter taste in your mouth while taking tamoxifen. Some foods may also taste different than they did before.

Trying new foods, replacing foods you can’t tolerate, or even using plastic utensils may help with taste changes. These taste changes usually last throughout the course of treatment and resolve a few months after you finish treatment.

Menopause happens when levels of sex hormones, including estrogen, drop sharply. Tamoxifen changes how estrogen works in your body. This can cause symptoms that feel like menopause, especially if you haven’t yet gone through menopause yet.

You may have a range of symptoms, including:

• Irregular periods
• Hot flashes
• Vaginal dryness
• Night sweats
• Mood swings
• Weight gain
• Thinning hair or hair loss

Many MyBCTeam members have talked about menopause-related side effects. “I had my first tamoxifen hot flash last night,” commented one. “It felt like my body was on fire.”

Mood changes and depression can happen during or after breast cancer treatment for many reasons, including stress, hormone shifts, and medication side effects. If you feel very depressed, hopeless, or like you might hurt yourself, seek help right away.

Note: If you or someone you know needs help, you can contact the 988 Suicide & Crisis Lifeline by calling or texting 988 or using the online chat.

Some people taking hormone therapies like tamoxifen have changes in their sleep patterns, such as trouble falling asleep, staying asleep, and waking up too early in the morning.

“I have taken tamoxifen for a year and a half,” posted one member. “The only side effect was insomnia, which got better when I started taking [the medication] in the morning.”

If you have insomnia, be careful with over-the-counter sleep medications like Tylenol PM or ZzzQuil. Some medications contain diphenhydramine or doxylamine, which may affect how your body processes tamoxifen through an enzyme called CYP2D6.

Check sleep aid labels for these ingredients, and ask your doctor or oncology pharmacist before using any sleep aid.

Nondrug treatment options like cognitive behavioral therapy (CBT) for insomnia may also help you get more sleep. CBT is a type of talk therapy that helps people change thoughts and habits that may be affecting their sleep.

Tamoxifen may cause changes to your menstrual cycle. Periods may become irregular, lighter or heavier than usual, or even stop altogether.

Alternatively, your menstrual period might stop because you are naturally going through menopause, or your chemotherapy treatments triggered early menopause.

Although no research shows tamoxifen causes weight gain directly, you might find that you have to go up a clothing size while taking it.

You may feel swollen or puffy due to edema, which happens when tamoxifen makes your body hold on to more fluid than usual.

“I was swelling up in my face and ankles,” wrote one MyBCTeam member who previously took tamoxifen.

Fatigue is one of the most common tamoxifen side effects. Even with enough sleep or rest, this extreme tiredness might linger, and even basic tasks may feel too difficult. Your legs or arms might also feel heavy, as though you have to work harder to move them.

One member taking tamoxifen shared, “I’m having a really hard time today getting myself together. I’m feeling really, really down, and I’m just so exhausted that all I wanna do is sleep.”

If fatigue is getting in the way of living your life, talk to your healthcare provider. Getting more physical activity, meditating, going to therapy, and improving your diet may help you manage this side effect.

Tamoxifen sometimes leads to nausea or indigestion, especially when you first start treatment.

“I think my stomach is bloated, and nausea comes and goes,” said one MyBCTeam member taking this medication.

These side effects are usually mild. Taking tamoxifen with food may make them less uncomfortable. They often go away after you stop taking the medication.

Tamoxifen may cause dry skin, rash, or itching in some people. As with many other tamoxifen side effects, these skin problems often resolve themselves once you finish treatment.

Occasionally, some people develop patches of skin that may look red or pink on lighter skin tones or purple, brown, gray, or darker than the surrounding skin on darker skin tones. These patches may turn into blisters or cause large areas of skin to peel.

In some cases, a rash can be a sign of an allergic reaction. Tell your doctor right away if you notice bumps, raised patches of skin, blisters, peeling, or skin or throat swelling.

Tamoxifen can cause symptoms that are also common during menopause, including vaginal dryness. However, this medication can also lead to more vaginal discharge than usual.

Although some differences in vaginal discharge are normal while you’re using tamoxifen, you should tell your doctor about certain changes.

Discharge that looks like cottage cheese and comes with itching or burning may be a sign of a yeast infection. Bloody discharge may be a sign of another medical condition.

Some of tamoxifen’s side effects, including vaginal dryness, fatigue, and nausea, may leave you less interested in sex or make it harder to become aroused or have an orgasm.

One MyBCTeam member shared their experiences with these side effects: “I’ve been on tamoxifen for a year now. [I’m] still having issues with not being able to climax, which is very upsetting.”

Men who take tamoxifen may experience a decreased sex drive and issues such as erectile dysfunction. Usually, these symptoms typically subside once you’re done using this medication.

Tamoxifen may affect your cognitive (thinking and reasoning) abilities.

Some research has found that those who use tamoxifen tend to have memory problems and process information more slowly. This medication may also affect executive function — skills related to planning, focusing, multitasking, and self-control. If your thinking feels a little fuzzy, tamoxifen may be to blame.

While using this hormone therapy, there’s a small chance you may experience:

• Changes to your singing voice
• More facial hair
• Joint pain
• Headaches
• Muscle cramps in your legs, especially at night

Tell your doctor about any new physical or mental changes you notice. You could also have mild liver changes that usually don’t cause any symptoms.

Your doctor can provide medical advice and help determine whether these issues were caused by your treatment plan, your cancer, or other factors.

In rare cases, tamoxifen can cause more severe health problems. Contact a healthcare provider right away if you notice:

• Signs of a blood clot, such as pain, swelling, or coughing up blood
• Trouble breathing or chest pain
• A fever
• Symptoms of stroke, like sudden muscle weakness, confusion, or blurry vision
• Dimmed or cloudy vision, which may be a sign of cataracts or other eye problems
• Yellowing of the skin or eyes, which can signal liver problems
• High calcium levels in people whose breast cancer has spread to the bones — Symptoms may include nausea, vomiting, constipation, thirst, frequent urination, confusion, or weakness.
• Signs of low blood cell counts, such as unusual bruising or bleeding, frequent infections, fever, or extreme tiredness

Tamoxifen can also increase the risk of endometrial (uterine) cancer. This risk is higher in people who are postmenopausal or have taken the drug for many years, but the overall risk remains low.

Side effects can vary from person to person. Some side effects may be scary or unexpected. In many cases, these changes are part of treatment and can be managed with help from your care team.

Tell your doctor about any new or worsening symptoms, especially unusual bleeding, chest pain, trouble breathing, signs of a blood clot, or symptoms that affect your daily life.

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

What has helped you with side effects while taking tamoxifen? Let others know in the comments below.