Tamoxifen interactions

Tamoxifen (Soltamox, Nolvadex), a selective estrogen receptor modulator has 84 documented interactions across the FDA labels and fact sheets we index: 47 major, 26 moderate, 10 minor, and 1 where a label reports no significant interaction. Each entry below quotes the sentence behind it. This drug page is a starting point, not a verdict for your situation.

Major interactions (47)

  • AmiodaroneantiarrhythmicMajor

    Reserve the combination of amiodarone with other antiarrhythmic therapies that prolong the QTc to patients with life-threatening ventricular arrhythmias who are incompletely responsive to a single agent. (Amiodarone label, Warnings and precautions)

  • Anastrozolearomatase inhibitorMajor

    Anastrozole and letrozole: Should not be used in combination with tamoxifen. (Tamoxifen label, Drug interactions)

  • ApixabananticoagulantMajor

    For women with DCIS and for the reduction in breast cancer incidence in women at high risk, tamoxifen is contraindicated in women who require concomitant warfarin-type anticoagulant therapy or in women with a history of deep vein thrombosis or pulmonary embolus. (Tamoxifen label, Warnings and precautions)

  • AprepitantCYP3A4 inhibitorMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • ArmodafinilCNS stimulantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • Azithromycinmacrolide antibioticMajor

    This risk which can be fatal should be considered in patients with certain cardiovascular disorders including known QT prolongation or history torsades de pointes, those with proarrhythmic conditions, and with other drugs that prolong the QT interval. (Azithromycin label, Warnings and precautions)

  • BosentanCYP3A4 inducerMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • CarbamazepineanticonvulsantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • CenobamateanticonvulsantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • ChloroquineantimalarialMajor

    Tamoxifen: Concomitant use of chloroquine with drugs known to induce retinal toxicity such as tamoxifen is not recommended (see WARNINGS ). (Chloroquine label, Drug interactions)

  • CiprofloxacinfluoroquinoloneMajor

    Avoid use in patients with known prolongation, those with hypokalemia, and with other drugs that prolong the QT interval. (Ciprofloxacin label, Warnings and precautions)

  • ClobazambenzodiazepineMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • DabigatrananticoagulantMajor

    For women with DCIS and for the reduction in breast cancer incidence in women at high risk, tamoxifen is contraindicated in women who require concomitant warfarin-type anticoagulant therapy or in women with a history of deep vein thrombosis or pulmonary embolus. (Tamoxifen label, Warnings and precautions)

  • Deferasiroxiron supplementMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • DexamethasonecorticosteroidMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • DofetilideantiarrhythmicMajor

    Use with Drugs that Prolong QT Interval and Antiarrhythmic Agents The use of dofetilide in conjunction with other drugs that prolong the QT interval has not been studied and is not recommended. (Dofetilide label, Warnings)

  • EdoxabananticoagulantMajor

    For women with DCIS and for the reduction in breast cancer incidence in women at high risk, tamoxifen is contraindicated in women who require concomitant warfarin-type anticoagulant therapy or in women with a history of deep vein thrombosis or pulmonary embolus. (Tamoxifen label, Warnings and precautions)

  • EnoxaparinanticoagulantMajor

    For women with DCIS and for the reduction in breast cancer incidence in women at high risk, tamoxifen is contraindicated in women who require concomitant warfarin-type anticoagulant therapy or in women with a history of deep vein thrombosis or pulmonary embolus. (Tamoxifen label, Warnings and precautions)

  • EslicarbazepineanticonvulsantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • Fluconazoleazole antifungalMajor

    Coadministration of other drugs known to prolong the QT interval and which are metabolized via the enzyme CYP3A4 such as erythromycin, pimozide, and quinidine are contraindicated in patients receiving fluconazole. (Fluconazole label, Contraindications)

  • FondaparinuxanticoagulantMajor

    For women with DCIS and for the reduction in breast cancer incidence in women at high risk, tamoxifen is contraindicated in women who require concomitant warfarin-type anticoagulant therapy or in women with a history of deep vein thrombosis or pulmonary embolus. (Tamoxifen label, Warnings and precautions)

  • FosfomycinantibioticMajor

    Avoid co-administration of CONTEPO with drugs known to prolong the QT interval. (Fosfomycin label, Drug interactions)

  • GriseofulvinantifungalMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • HeparinanticoagulantMajor

    For women with DCIS and for the reduction in breast cancer incidence in women at high risk, tamoxifen is contraindicated in women who require concomitant warfarin-type anticoagulant therapy or in women with a history of deep vein thrombosis or pulmonary embolus. (Tamoxifen label, Warnings and precautions)

  • HydroxychloroquineQT-prolonging drugMajor

    Therefore, PLAQUENIL is not recommended in patients taking other drugs that have the potential to prolong the QT interval. (Hydroxychloroquine label, Warnings and precautions)

  • IloperidoneantipsychoticMajor

    Avoid the use of FANAPT in combination with any other drugs that prolong the QT interval [see Warnings and Precautions (5.3) ] . (Iloperidone label, Drug interactions)

  • Bradycardia may increase the risk of QT prolongation which may lead to severe ventricular arrhythmias, including torsade de pointes, especially in patients with risk factors such as use of QTc prolonging drugs [see Adverse Reactions ( 6.2 )] . (Ivabradine label, Warnings and precautions)

  • Letrozolearomatase inhibitorMajor

    Anastrozole and letrozole: Should not be used in combination with tamoxifen. (Tamoxifen label, Drug interactions)

  • LevofloxacinfluoroquinoloneMajor

    Avoid use in patients with known prolongation, those with hypokalemia, and with other drugs that prolong the QT interval ( 5.11 , 8.5 ) (Levofloxacin label, Warnings and precautions)

  • MirtazapineantidepressantMajor

    Examples diazepam, alprazolam, alcohol Drugs that Prolong QTc Interval Clinical Impact The concomitant use of other drugs which prolong the QTc interval with REMERON/REMERONSolTab, increase the risk of QT prolongation and/or ventricular arrhythmias (e.g., Torsades de Pointes). (Mirtazapine label, Drug interactions)

  • ModafinilCNS stimulantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • OxcarbazepineanticonvulsantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • ParoxetineSSRIMajor

    When tamoxifen is used for the treatment or prevention of breast cancer, weigh the likely benefit of BRISDELLE for treating moderate to severe VMS associated with menopause vs. the risk of possible decreased tamoxifen effectiveness, and consider avoiding the concomitant use of BRISDELLE. (Paroxetine label, Warnings and precautions)

  • PhenobarbitalbarbiturateMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • Phentermine and topiramateCNS stimulantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • PhenytoinanticonvulsantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • PitolisantQT-prolonging drugMajor

    The use of WAKIX should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong the QT interval [see Drug Interactions ( 7.1 )]. (Pitolisant label, Warnings and precautions)

  • PrimidoneanticonvulsantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • PropafenoneantiarrhythmicMajor

    • Avoid use with other antiarrhythmic agents or drugs that prolong the QT interval. (Propafenone label, Warnings and precautions)

  • RifampinantibioticMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • RitonavirantiretroviralMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • RivaroxabananticoagulantMajor

    For women with DCIS and for the reduction in breast cancer incidence in women at high risk, tamoxifen is contraindicated in women who require concomitant warfarin-type anticoagulant therapy or in women with a history of deep vein thrombosis or pulmonary embolus. (Tamoxifen label, Warnings and precautions)

  • SertralineSSRIMajor

    Avoid the concomitant use of drugs known to prolong the QTc interval. (Sertraline label, Drug interactions)

  • TetrabenazineVMAT2 inhibitorMajor

    Certain conditions may increase the risk for torsade de pointes or sudden death such as (1) bradycardia; (2) hypokalemia or hypomagnesemia; (3) concomitant use of other drugs that prolong the QTc interval; and (4) presence of congenital prolongation of the QT interval [see Warnings and Precautions ( 5.8 ), Clinical Pharmacology (12.2) ]. (Tetrabenazine label, Drug interactions)

  • TopiramateanticonvulsantMajor

    Inducers of CYP3A4 Strong CYP3A4 inducers should not be used with tamoxifen. (Tamoxifen label, Drug interactions)

  • WarfarinanticoagulantMajor

    SOLTAMOX is contraindicated in patients who require concomitant warfarin therapy or have a history of deep vein thrombosis or pulmonary embolus if the indication for treatment is either reduction of breast cancer incidence in high-risk patients or risk reduction of invasive breast cancer after treatment of DCIS [see Warnings and Precautions (5.2) and Drug Interactions… (Tamoxifen label, Contraindications)

  • ZiprasidoneantipsychoticMajor

    …drugs, ziprasidone is contraindicated: • in patients with a known history of QT prolongation (including congenital long QT syndrome) • in patients with recent acute myocardial infarction • in patients with uncompensated heart failure Pharmacokinetic/pharmacodynamic studies between ziprasidone and other drugs that prolong the QT interval have not been performed. (Ziprasidone label, Contraindications)

Moderate interactions (26)

  • BuprenorphineopioidModerate

    The risk of combining buprenorphine with other QT-prolonging agents is not known. (Buprenorphine label, Warnings and precautions)

  • The risk of combining buprenorphine with other QT-prolonging agents is not known. (Buprenorphine and naloxone label, Warnings and precautions)

  • BupropionantidepressantModerate

    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. (Bupropion label, Drug interactions)

  • CitalopramSSRIModerate

    Avoid use of Citalopram Capsules in patients with congenital long QT syndrome, bradycardia, hypokalemia or hypomagnesemia, recent acute myocardial infarction, or uncompensated heart failure and patients taking other drugs that prolong the QTc interval. (Citalopram label, Warnings and precautions)

  • Conjugated estrogensestrogenModerate

    Hypercalcemia in Patients with Metastatic Breast Cancer As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. (Tamoxifen label, Warnings and precautions)

  • Drospirenone and ethinyl estradioloral contraceptiveModerate

    Hypercalcemia in Patients with Metastatic Breast Cancer As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. (Tamoxifen label, Warnings and precautions)

  • EstradiolestrogenModerate

    Hypercalcemia in Patients with Metastatic Breast Cancer As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. (Tamoxifen label, Warnings and precautions)

  • FentanylopioidModerate

    …prolonged QT interval, 3) treatment with Class 1 and Class III antiarrhythmics, 4) treatment with monoamine oxidase inhibitors (MAOI's), 5) concomitant treatment with other drug products known to prolong the QT interval and 6) electrolyte imbalance, in particular hypokalemia and hypomagnesemia, or concomitant treatment with drugs (e.g., diuretics) that may cause electrolyte… (Fentanyl label, Warnings and precautions)

  • FluoxetineSSRIModerate

    Use with caution in combination with other drugs that prolong the QT interval ( 4.2 , 5.11 , 7.7 , 7.8 ) 7.1 Monoamine Oxidase Inhibitors (MAOI) [See Dosage and Administration ( 2.9 , 2.10 ), Contraindications ( 4.1 ), and Warnings and Precautions ( 5.2 )] . (Fluoxetine label, Drug interactions)

  • Formoterolbeta-adrenergic agonistModerate

    …Antidepressants, QTc Prolonging Drugs Formoterol, as with other beta 2 -agonists, should be administered with extreme caution to patients being treated with monoamine oxidase inhibitors, tricyclic antidepressants, or drugs known to prolong the QTc interval because the effect of adrenergic agonists on the cardiovascular system may be potentiated by these agents. (Formoterol label, Drug interactions)

  • HaloperidolantipsychoticModerate

    Concomitant use of HALDOL DECANOATE with other products that prolong the QTc interval may result in a greater increase in the QTc interval, and adverse reactions associated with QTc interval prolongation, including torsade de pointes, other serious arrythmias, and sudden death [see Warnings and Precautions (5.2) ]. (Haloperidol label, Drug interactions)

  • Levonorgestrel and ethinyl estradioloral contraceptiveModerate

    Hypercalcemia in Patients with Metastatic Breast Cancer As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. (Tamoxifen label, Warnings and precautions)

  • Levothyroxinethyroid hormoneModerate

    Drug-Laboratory Test Interactions There are postmarketing reports of T 4 elevations in postmenopausal patients taking tamoxifen that may be explained by increases in thyroid-binding globulin. (Tamoxifen label, Drug interactions)

  • Liothyroninethyroid hormoneModerate

    Drug-Laboratory Test Interactions There are postmarketing reports of T 4 elevations in postmenopausal patients taking tamoxifen that may be explained by increases in thyroid-binding globulin. (Tamoxifen label, Drug interactions)

  • Lofexidinealpha-adrenergic agonistModerate

    Risk of QT Prolongation : Lofexidine tablets prolong the QT interval. (Lofexidine label, Warnings and precautions)

  • Methimazoleantithyroid drugModerate

    Drug-Laboratory Test Interactions There are postmarketing reports of T 4 elevations in postmenopausal patients taking tamoxifen that may be explained by increases in thyroid-binding globulin. (Tamoxifen label, Drug interactions)

  • MetronidazoleantibioticModerate

    Drugs that Prolong the QT Interval QT prolongation has been reported, particularly when metronidazole was administered with drugs with the potential for prolonging the QT interval. (Metronidazole label, Drug interactions)

  • MoxifloxacinfluoroquinoloneModerate

    Pharmacokinetic studies between moxifloxacin and other drugs that prolong the QT interval such as cisapride, erythromycin, antipsychotics, and tricyclic antidepressants have not been performed. (Moxifloxacin label, Warnings and precautions)

  • Norethindrone and ethinyl estradioloral contraceptiveModerate

    Hypercalcemia in Patients with Metastatic Breast Cancer As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. (Tamoxifen label, Warnings and precautions)

  • Norgestimate and ethinyl estradioloral contraceptiveModerate

    Hypercalcemia in Patients with Metastatic Breast Cancer As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. (Tamoxifen label, Warnings and precautions)

  • PaliperidoneantipsychoticModerate

    …combination with other drugs that are known to prolong QTc including Class 1A (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmic medications, antipsychotic medications (e.g., chlorpromazine, thioridazine), antibiotics (e.g., gatifloxacin, moxifloxacin), or any other class of medications known to prolong the QTc interval. (Paliperidone label, Warnings and precautions)

  • Propylthiouracilantithyroid drugModerate

    Drug-Laboratory Test Interactions There are postmarketing reports of T 4 elevations in postmenopausal patients taking tamoxifen that may be explained by increases in thyroid-binding globulin. (Tamoxifen label, Drug interactions)

  • QuetiapineantipsychoticModerate

    …Class 1A antiarrythmics (e.g., quinidine, procainamide) or Class III antiarrythmics (e.g., amiodarone, sotalol), antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine), antibiotics (e.g., gatifloxacin, moxifloxacin), or any other class of medications known to prolong the QTc interval (e.g., pentamidine, levomethadyl acetate, methadone). (Quetiapine label, Warnings and precautions)

  • Sotalolbeta blockerModerate

    Additive to other QT-prolonging drugs ( 7.1 , 7.2 ) (Sotalol label, Drug interactions)

  • TestosteroneandrogenModerate

    Hypercalcemia in Patients with Metastatic Breast Cancer As with other additive hormonal therapy (estrogens and androgens), hypercalcemia has been reported in some breast cancer patients with bone metastases within a few weeks of starting treatment with tamoxifen. (Tamoxifen label, Warnings and precautions)

  • Umeclidinium and vilanterolanticholinergicModerate

    …like other beta 2 -agonists, should be administered with extreme caution to patients being treated with monoamine oxidase inhibitors, tricyclic antidepressants, or drugs known to prolong the QTc interval or within 2 weeks of discontinuation of such agents, because the effect of adrenergic agonists on the cardiovascular system may be potentiated by these agents. (Umeclidinium and vilanterol label, Drug interactions)

Minor mentions (10)

  • CimetidineH2 blockerMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • DarifenacinanticholinergicMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • DiphenhydramineantihistamineMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • DuloxetineSNRIMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • EverolimusimmunosuppressantMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • ImatinibCYP3A4 inhibitorMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • Mirabegronbeta-adrenergic agonistMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • Naltrexone and bupropionopioid antagonistMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • RanolazineQT-prolonging drugMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

  • TerbinafineantifungalMinor

    Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

No significant interaction reported (1)

  • DesvenlafaxineSNRINo interaction

    …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) ]. (Desvenlafaxine label, Drug interactions)

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Not medical advice. Severity reflects the label's wording, not your circumstances. A "major" flag can be routine under supervision and a "minor" one can matter at high doses. Ask a pharmacist.