Soltamox (Tamoxifen Citrate) for Breast Cancer

Soltamox (tamoxifen citrate) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat certain adults with breast cancer.

How Soltamox Works and How It’s Taken

Soltamox is an estrogen agonist and antagonist. This means it can block or act like estrogen in different parts of the body. In breast tissue, it competes with estrogen for estrogen receptors. This can reduce signals that help some breast cancer cells grow.

Doctors prescribe Soltamox:

To treat adults with estrogen receptor-positive breast cancer that has spread to other parts of the body
To treat adults with early-stage estrogen receptor-positive breast cancer after initial treatment
To reduce the chance of cancer developing in the other breast during adjuvant treatment
To reduce the risk of invasive breast cancer in adult women with ductal carcinoma in situ (DCIS) after breast surgery and radiation
To reduce the risk of breast cancer in adult women at high risk

Soltamox is an oral solution taken by mouth. Soltamox can be taken with or without food. Your healthcare provider will tell you how much to take, when to take it, and how long to continue treatment.

Typical Dosing for Breast Cancer

For metastatic breast cancer, the recommended dose is 20 to 40 milligrams each day. Doses greater than 20 milligrams per day should be divided into a morning dose and an evening dose.

For early-stage breast cancer after initial treatment, the recommended dose is 20 milligrams each day for five to 10 years. Doses greater than 20 milligrams daily do not provide added clinical benefit.

For DCIS after breast surgery and radiation, the recommended dose is 20 milligrams each day for five years.

For reducing breast cancer incidence in women at high risk, the recommended dose is 20 milligrams each day for five years.

Use the dosing cup that comes with Soltamox to measure each dose. Ask your healthcare provider or pharmacist if you are not sure how to measure it.

Do not stop taking Soltamox without first talking with your healthcare provider.

This information is based on prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.

Soltamox Side Effects

In clinical studies of Soltamox for breast cancer, side effects differed depending on how Soltamox was used.

For adjuvant breast cancer, the most common side effects include:

Hot flashes
Vaginal discharge
Vaginal bleeding
Nausea
Fluid retention

For metastatic breast cancer, the most common side effect is hot flashes.

Serious Side Effects and Warnings

Soltamox can cause serious side effects that may require immediate medical attention. These include:

Uterine malignancies — Malignancies, such as endometrial cancer and uterine sarcoma, can occur.
Stroke — Soltamax can increase the risk of stroke.
Thromboembolic events — Blood clots, including deep vein thrombosis and pulmonary embolism, can occur.
Embryo-fetal toxicity — If taken during pregnancy, the baby may be harmed.
Liver problems — Problems with the liver, including liver cancer and severe liver injury, can occur.
High calcium levels — Hypercalcemia can occur in people with metastatic breast cancer that has spread to the bones.
Hematologic effects — Low blood cell counts, including low platelets, low white blood cells, neutropenia, anemia, and pancytopenia, can occur.
Eye problems — Problems with the eyes, such as corneal changes, retinal vein thrombosis, retinopathy, and cataracts, can occur.
Severe allergic reactions — Allergic reactions can occur, including angioedema.

Get medical help right away if you think you are having a serious reaction.

How To Save on Soltamox

Mayne Pharma, the manufacturer of Soltamox, offers the Soltamox Mayne Pharma Patient Savings Card. Eligible people with commercial insurance may pay as little as $0.

Eligible people whose insurance does not cover Soltamox may pay as little as $60.

To learn more, visit the Soltamox Mayne Pharma Patient Savings Card or call 347-442-7919.

What To Know Before Taking Soltamox

Before starting Soltamox, your doctor will check for pregnancy if you can become pregnant.

Do not take Soltamox if you have had a serious allergic reaction to tamoxifen or any ingredient in Soltamox.

If you have DCIS or are taking Soltamox to reduce your risk of breast cancer, do not take it if you:

Need to take warfarin, a blood thinner
Have had a blood clot in your veins or lungs

Before taking Soltamox, tell your healthcare provider if you:

Have uterine cancer or another problem with your uterus
Have irregular periods, no periods, or abnormal vaginal bleeding
Have or have had a blood clot in your veins or lungs
Have had a stroke
Are pregnant, plan to become pregnant, or are breastfeeding

Tell your doctor about all medicines you take, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements.

Tell your doctor if you have any allergies to tamoxifen citrate or any ingredients in Soltamox.

If you miss a dose of Soltamox, take it when you remember. Then take your next dose at the usual time. If it is almost time for your next dose, skip the missed dose. Do not take two doses at the same time. Call your healthcare provider if you are not sure what to do.

Soltamox can harm your baby if you are pregnant. Use effective nonhormonal birth control during treatment and for two months after your last dose. Do not breastfeed during treatment or for three months after your last dose.

Community FAQs

These answers are fact-checked by our editorial staff.

How effective is Soltamox for breast cancer?

In studies of women with early breast cancer that was estrogen receptor-positive or had unknown estrogen receptor status, about five years of tamoxifen improved 10-year overall survival.

Among women with positive lymph nodes, 61.4 percent were alive at 10 years with tamoxifen, compared with 50.5 percent without it. Among women with negative lymph nodes, 78.9 percent were alive at 10 years with tamoxifen, compared with 73.3 percent without it.

In the ATLAS clinical study, women who continued tamoxifen for a total of 10 years had about a 13 percent lower risk of dying from breast cancer than women who stopped after five years.

Tamoxifen also reduced the yearly rate of cancer in the opposite breast from 7.6 to 3.9 cases per 1,000 people.

Can Soltamox be used with other medicines for breast cancer?

Some medicine combinations should be avoided or are not recommended.

Anastrozole should not be used with Soltamox because the combination did not work better than Soltamox alone. Letrozole is also not recommended with Soltamox because the benefit of using them together has not been established.

Soltamox can interact with warfarin, a blood thinner. Whether it can be used with warfarin depends on why Soltamox is being taken.

Strong CYP3A4 inducers, such as rifampin, can make the body break down Soltamox faster. This may lower the amount of medicine in the body, so these drugs should not be used together.

Strong CYP2D6 inhibitors, such as paroxetine, can block an enzyme the body uses to turn tamoxifen into an active form. This may lower levels of the active form, but the effect on how well treatment works is not clear.

Can Soltamox be used in men for breast cancer?

Yes. Soltamox may be used to treat adult men with estrogen receptor-positive metastatic breast cancer. Metastatic means the cancer has spread to other parts of the body. Soltamox competes with estrogen for estrogen receptors in breast tissue. This can reduce signals that help some breast cancer cells grow. The prescribing information also says tamoxifen is effective for palliative treatment in men with metastatic breast cancer.