tamoxifen
Brand names: Nolvadex
Tamoxifen (Soltamox) is a medicine that can treat breast cancer. It can also lower the chance of getting breast cancer in some people.
Drug Pricing (NADAC)
Generic Price
$0.12/unit
Generic Available
Yes (4 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine is used to treat breast cancer that has spread in adults.
Common side effects
Hot flashes, Mood changes, Vaginal discharge
Key warnings
Tamoxifen can cause serious and life-threatening problems, including cancer of the uterus, stroke, and blood clots in the lungs.
How It Works
Tamoxifen belongs to a class of drugs called Selective Estrogen Receptor Modulators (SERMs). It works by blocking the effects of estrogen in breast tissue. This can help to stop the growth of breast cancer cells.
How to Take It
Take this medicine exactly as your doctor tells you. For metastatic breast cancer, the usual dose is 20 to 40 mg per day. If you take more than 20 mg a day, divide the dose into two, taking one in the morning and one in the evening. For other uses, the usual dose is 20 mg per day for 5-10 years.
Pregnancy & Breastfeeding
Tamoxifen can harm an unborn baby. If you are a woman who could become pregnant, your doctor will perform a pregnancy test before you start taking tamoxifen. Use effective birth control while taking tamoxifen and for several months after your last dose. Do not breastfeed while taking this medicine.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store at room temperature, away from light, and do not freeze or refrigerate. Discard any unused portion after 3 months of first opening the bottle.
Side Effects (from patient reports)
Based on 2,638 FDA adverse event reports.
Serious Warnings
Tamoxifen can cause serious and life-threatening problems, including cancer of the uterus, stroke, and blood clots in the lungs. Some cases have been fatal. Talk to your doctor about the risks and benefits of taking tamoxifen, especially if you are at high risk for breast cancer or have DCIS. For most people already diagnosed with breast cancer, the benefits of tamoxifen outweigh the risks.
Known Drug Interactions
( 7.1 ) Warfarin: Do not use in patients taking tamoxifen for DCIS and for reduction in breast cancer incidence in women at high risk. Warfarin A marked increase in anticoagulant effect may occur when tamoxifen is used in combination with warfarin. Closely monitor coagulation indices in patients who are taking tamoxifen for either the treatment of metastatic breast cancer or as adjuvant therapy who require concomitant use of warfarin [see Contraindications (4) ] .
Mechanism: Tamoxifen increases the blood-thinning effects of warfarin, which can lead to a much higher risk of dangerous bleeding.
What to do: Avoid using these together if you are taking tamoxifen for cancer prevention, or have your doctor check your blood clotting levels very often.
7 DRUG INTERACTIONS Tamoxifen: Do not use in combination with anastrozole. No additional benefit seen over tamoxifen monotherapy ( 7.1 , 14.1 ). 7.1 Tamoxifen Co-administration of anastrozole and tamoxifen in breast cancer patients reduced anastrozole plasma concentration by 27%.
Mechanism: Tamoxifen lowers the amount of anastrozole in your blood, which may make the treatment less effective against cancer. Research also shows that taking both drugs together provides no extra benefit compared to taking just one.
What to do: Do not use these two drugs at the same time. Your doctor will usually have you take only one of these medications for your treatment.
7 DRUG INTERACTIONS Anastrozole and letrozole: Should not be used in combination with tamoxifen. Letrozole The concomitant use of letrozole with tamoxifen is not recommended because the efficacy of the combination in the adjuvant treatment of breast cancer has not been established. Tamoxifen reduced the plasma concentration of letrozole by 38% when these drugs were co-administered [see Clinical Pharmacology (12.3) ].
Mechanism: Tamoxifen lowers the amount of letrozole in your blood, and it is not known if taking both together helps treat cancer effectively.
What to do: You should avoid using these two medications at the same time.
Drugs that require metabolic activation by CYP2D6 to be effective (e.g., tamoxifen), theoretically could have reduced efficacy when administered concomitantly with inhibitors of CYP2D6 such as bupropion.
Mechanism: Bupropion prevents tamoxifen from being changed into its active form, which could make the tamoxifen less effective at treating cancer.
What to do: Your doctor may suggest a different medication that does not interfere with how tamoxifen works.
Examples desipramine, atomoxetine, dextromethorphan, metoprolol, nebivolol, perphenazine, tolterodine 7.2 Drugs Having No Clinically Important Interactions with PRISTIQ Based on pharmacokinetic studies, no dosage adjustment is required for drugs that are mainly metabolized by CYP3A4 (e.g., midazolam), or for drugs that are metabolized by both CYP2D6 and CYP3A4 (e.g., tamoxifen, aripiprazole), when administered concomitantly with PRISTIQ [see Clinical Pharmacology (12.3) ].
Mechanism: Desvenlafaxine does not change the way the body breaks down tamoxifen.
What to do: These medications can be used together without changing your dosage.
Common Questions
What should I do if I experience abnormal vaginal bleeding?
Can I take anastrozole or letrozole with tamoxifen?
What should I do if I am taking warfarin?
How long should I take tamoxifen?
What are the signs of a blood clot?
Can tamoxifen affect my liver?
What if I am already taking other medications?
How will I know if the medicine is working?
What should I do if I experience hot flashes?
Is there anything else I should avoid while taking tamoxifen?
What are the common side effects of tamoxifen?
Does tamoxifen interact with other medications?
What drug class is tamoxifen?
Is tamoxifen safe during pregnancy?
Related Medications in Selective Estrogen Receptor Modulator (SERM)
Other drugs grouped near tamoxifen — same-class peers and common alternatives.
abiraterone
Zytiga
Abiraterone (Zytiga) is a medicine used with prednisone to treat prostate cancer that has spread.
Compare with tamoxifen →
anastrozole
Arimidex
Anastrozole is a medicine used to treat breast cancer in women after menopause.
Compare with tamoxifen →
bazedoxifene/conjugated estrogens
Duavee
Duavee is a combination medicine containing estrogen and a drug that blocks estrogen in some parts of the body.
Compare with tamoxifen →
cabergoline
Dostinex
Cabergoline is a medicine that helps lower the amount of prolactin in your body.
Compare with tamoxifen →
clomiphene
Clomid, Serophene
Clomiphene citrate is a medicine that helps women ovulate.
Compare with tamoxifen →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
Related Health & Safety Data
🩺 Find a Doctor
Search prescribers for Selective Estrogen Receptor Modulator (SERM)
🏨 Hospital Quality
CMS hospital ratings, safety scores & patient outcomes
💊 Supplement Data
NIH DSLD — check supplement ingredients & label claims
🍽️ Food Safety Alerts
FDA recalls, inspections & outbreak investigations
⚠️ Product Recalls
FDA, CPSC & NHTSA recall search
💉 Procedure Costs
Medicare procedure pricing for 9,297 procedures
Save on tamoxifen
Compare prices and find discounts at pharmacies near you. Free coupons can save up to 80% on prescriptions.
Disclosure: This link may earn us a commission at no extra cost to you. See our terms.
What the FDA Data Shows for tamoxifen
The FDA label for tamoxifen (sold under brand names such as Nolvadex) classifies it as a prescription-only medication in the Selective Estrogen Receptor Modulator (SERM) class. This medicine is used to treat breast cancer that has spread in adults. Official labeling lists 6 commonly reported side effects, including Hot flashes, Mood changes, Vaginal discharge.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 2,638 voluntary reports. The database also lists 10 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated major severity. NADAC pricing from CMS shows a generic unit cost of $0.12.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: November 29, 2021
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages