Soltamox (Tamoxifen) - Oral


Soltamox has the potential to cause life-threatening effects, such as blood clots, stroke, and uterine cancer.

What Is Soltamox?

Soltamox (tamoxifen) is an oral liquid medication, a selective estrogen receptor modulator, used to treat certain types of breast cancer. It can also be used to help prevent breast cancer in women who are at high risk.

Soltamox works by preventing estrogen from attaching to cancer cells in the breast. This only works for cancer that is estrogen-receptor positive (ER+), meaning the cancer uses estrogen to grow.

Soltamox is available in liquid (solution) form.

Drug Facts

Generic Name: Tamoxifen

Brand Name(s): Soltamox

Drug Availability: Prescription

Administration Route:  Oral

Therapeutic Classification: Selective estrogen receptor modulator

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Tamoxifen citrate

Dosage Form(s): Solution

What Is Soltamox Used For?

Soltamox is used to:

  • Treat ER+ breast cancer that is metastatic (grown to areas outside of the breast)
  • Treat early-stage breast ER+ cancer after surgery, chemotherapy, and/or radiation
  • Reduce the risk of developing breast cancer in those who are at high risk
  • Reduce the risk of cancer development in ductal carcinoma in situ (DCIS), a non-invasive or pre-invasive breast cancer, after chemotherapy and radiation

How to Take Soltamox

Take Soltamox as directed by your oncologist. Measure the oral solution with the provided dosing cup. You can take it with or without food.

Although treatment length may vary from person to person, Soltamox is often taken for five to 10 years.


Soltamox should be stored in its original container, which protects it from light. Keep the bottle closed tightly after use.

Soltamox should be stored at room temperature (between 68 F and 77 F) and not in the refrigerator or bathroom. It is only good for three months once opened and should be discarded if opened longer.

Off-Label Uses 

Soltamox is sometimes prescribed off-label for conditions other than breast cancer treatment or cancer reduction. Some of these conditions include:

  • Endometrial cancer
  • Gynecomastia (breast enlargement in males)
  • Male infertility
  • Inducing ovulation as part of infertility treatment
  • Severe breast pain (mastalgia)
  • Ovarian cancer
  • McCune-Albright syndrome (a condition that affects the bones, skin, and hormone-producing tissues in the body)

What Are the Side Effects of Soltamox?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at or 800-FDA-1088.

Common Side Effects 

Some side effects are associated with Soltamox. The most common side effects include:

Severe Side Effects

You may also experience severe side effects from Soltamox. Call your healthcare provider immediately if you have serious side effects. Dial 911 if your symptoms feel life-threatening or if you think you're having a medical emergency. Serious side effects and their symptoms can include the following:

  • Uterine cancer and other uterine problems, such as endometriosis, fibroids, and irregular menstrual cycles
  • Blood clots, which can occur in the legs and travel to the lungs (pulmonary embolism)
  • Stroke
  • Liver dysfunction or liver cancer

Taking tamoxifen doesn't mean you will develop these side effects. However, don't hesitate to contact your oncology care team if you notice any unusual or worsening symptoms. It's always better to communicate new or worsening issues throughout your treatment.

Long-Term Side Effects 

The potential for long-term side effects exists. These are most likely complications of some of the severe symptoms listed above.

Tamoxifen carries a boxed warning (the FDA's strictest safety warning) regarding the potential for an increased risk of uterine malignancies, stroke, and pulmonary embolism.

Tell your healthcare provider if you notice symptoms such as:

  • Irregular menstrual bleeds or abnormal vaginal bleeds
  • Abnormal vaginal discharge
  • Pelvic pain or pressure
  • Sudden chest pain or shortness of breath
  • Coughing up blood
  • Pain, tenderness, or swelling in one or both of your legs
  • Sudden weakness, tingling, or numbness in the face, arm, or legs, especially on one side of the body
  • Sudden confusion or trouble speaking
  • Dizziness or loss of balance or coordination

Report Side Effects

Soltamox may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Soltamox Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (solution, tablets):
    • For breast cancer:
      • Adults—20 to 40 milligrams (mg) per day. Doses greater than 20 mg are given as 2 divided doses per day (morning and evening).
      • Children—Use and dose must be determined by your doctor.
    • For breast cancer as additional treatment:
      • Adults—20 milligrams (mg) per day for 5 to 10 years.
      • Children—Use and dose must be determined by your doctor.
    • For reducing the risk of developing breast cancer in high-risk women:
      • Adults—20 milligrams (mg) per day for 5 years.
      • Children—Use and dose must be determined by your doctor.
    • For reducing the risk of developing invasive breast cancer in women with ductal carcinoma in situ:
      • Adults—20 milligrams (mg) per day for 5 years.
      • Children—Use and dose must be determined by your doctor.


There are no dose modifications for people of various ages taking Soltamox. 

You should not breastfeed during treatment with Soltamox for three months after your last dose. Additionally, you must use effective contraception during and for six months after taking it, as this medication can cause harm to a developing fetus.

Missed Dose

If you miss a dose, take it as soon as you remember. However, if it is closer to the time of your next scheduled dose, skip the missed dose and resume your usual dosing schedule. Do not double up for a missed dose of Soltamox.

Overdose: What Happens If I Take Too Much Soltamox?

Notify your prescribing healthcare provider immediately if you take too much medication. Based on the amount taken, they may offer specific interventions or suggestions for observation.

What Happens if I Overdose on Soltamox?

If you think you or someone else may have overdosed on Soltamox, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Soltamox, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Do not use this medicine together with blood thinners (eg, warfarin).

Your doctor will give you a pregnancy test before you use this medicine to make sure you are not pregnant. Using this medicine while you are pregnant can harm your unborn baby. Birth control pills may not work as well to prevent pregnancy when used with this medicine. Use another form of birth control (eg, condoms, spermicide) along with your pills during treatment and for 2 months after the last dose. If you think you have become pregnant while using the medicine, tell your doctor right away.

This medicine may increase your risk for other cancers, including endometrium, liver, or uterus cancer. Tell your doctor if you have any changes in your menstrual period, such as irregular menstrual periods or no menstrual periods, or abnormal vaginal bleeding. It is important for women to have regular gynecologic check-ups while using this medicine. Talk to your doctor if you have concerns.

This medicine may increase your risk of developing blood clots. Check with your doctor right away if you have swelling and pain in your arms, legs, or stomach, chest pain, shortness of breath, loss of sensation, confusion, or problems with muscle control or speech.

This medicine may lower the number of some types of blood cells in your body. Because of this, you may bleed or get infections more easily. To help with these problems, avoid being near people who are sick or have infections. Wash your hands often. Stay away from rough sports or other situations where you could be bruised, cut, or injured. Brush and floss your teeth gently. Be careful when using sharp objects, including razors and fingernail clippers.

Check with your doctor right away if blurred vision, difficulty with reading, or any other change in vision occurs during or after treatment. Your doctor may want your eyes be checked by an ophthalmologist (eye doctor).

Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Soltamox?

You should not take Soltamox if you:

  • Are allergic to tamoxifen or any of the ingredients in Soltamox
  • Have DCIS or a high risk of breast cancer and must also take Jantoven (warfarin) or have a history of thrombosis or pulmonary embolism
  • Are pregnant (use effective birth control during treatment and for six months after your last dose)

What Other Medications Interact With Soltamox?

Before starting treatment, tell your healthcare provider about any other medicines you take or plan to take, including over-the-counter (OTC) nonprescription products, vitamins, herbs, supplements, and plant-based medicines.

Soltamox can interact with other medications. It should not be taken with the following:

Talk with your pharmacist or healthcare provider for more detailed information about medication interactions with Soltamox.

What Medications Are Similar?

Another available selective estrogen receptor modulator is Evista (raloxifene). Evista is not commonly used for breast cancer treatment. Instead, it is most often used to treat osteoporosis in women who have gone through menopause.

Frequently Asked Questions

  • How does Soltamox work?

    In ER+ breast cancer, Soltamox works by blocking the estrogen from attaching to the cancer cell. This way, the cancer is unable to access estrogen to grow. 

  • What drugs should not be taken with Soltamox?

    Some medications should not be taken with Soltamox. These medications include warfarin, letrozole, anastrozole, fluoxetine, and St. John's wort, among others. Ask your healthcare team for a complete list of potential drug interactions.

  • What are the side effects of Soltamox?

    Common side effects of Soltamox include hot flashes, mood swings, vaginal discharge and bleeding, nausea, and fluid retention. The more severe side effects of Soltamox include liver dysfunction, endometrial cancer, and blood clots.

How Can I Stay Healthy While Taking Soltamox?

Talk to your healthcare team about the potential side effects of your treatment. Often, if you have invasive breast cancer, the clinical benefits of tamoxifen are greater than the risks. Ask your healthcare team what symptoms to watch for to identify if your side effects become severe.

While undergoing cancer treatment, you can take charge of other aspects of your health. Eating a healthy diet and exercising as your body allows can help you feel better and reduce stress. Importantly, give yourself time to rest and recover. Don't hesitate to reach out to family, friends, or a support group to help you cope with your diagnosis.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. Food and Drug Administration. Soltamox label.

  2. Emons G, Mustea A, Tempfer C. Tamoxifen and endometrial cancer: a janus-headed drug. Cancers (Basel). 2020;12(9):2535. doi:10.3390/cancers12092535

  3. Wibowo E, Pollock PA, Hollis N, et al. Tamoxifen in men: a review of adverse events. Andrology. 2016;4(5):776-788. doi:10.1111/andr.12197

  4. Chua ME, Escusa KG, Luna S, et al. Revisiting oestrogen antagonists (clomiphene or tamoxifen) as medical empiric therapy for idiopathic male infertility: a meta-analysis. Andrology. 2013;1(5):749-757. doi:10.1111/j.2047-2927.2013.00107.x

  5. Dhaliwal LK, Suri V, Gupta KR, et al. Tamoxifen: an alternative to clomiphene in women with polycystic ovary syndrome. J Hum Reprod Sci. 2011;4(2):76-79. doi:10.4103/0974-1208.86085

  6. Singh DD, Dharanipragada K, D S, Manikandan S. Oral versus topical tamoxifen in cyclical mastalgia-a randomized controlled trial. Breast J. 2020;26(4):743-747. doi:10.1111/tbj.13674

  7. Prescribers' Digital Reference. Tamoxifen citrate - drug summary.

  8. American Cancer Society. Tamoxifen and raloxifene for lowering breast cancer risk.

By Julie Scott, MSN, ANP-BC, AOCNP
Julie is an Adult Nurse Practitioner with oncology certification and a healthcare freelance writer with an interest in educating patients and the healthcare community.