of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.insulin degludec/insulin aspartlevonorgestrel oral decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.insulin inhaledlevonorgestrel oral decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.istradefyllineistradefylline will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.ivosidenibivosidenib will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ivosidenib may decrease the concentrations of hormonal contraceptives, consider alternative methods of contraception in patients receiving ivosidenib. lamotriginelevonorgestrel oral will decrease the level or effect of lamotrigine by increasing hepatic clearance. Use Caution/Monitor. Combination oral contraceptives have been shown to significantly decrease plasma concentrations of lamotrigine, likely due to induction of lamotrigine glucuronidation.lenacapavirlenacapavir will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.liraglutidelevonorgestrel oral decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.maraviroclevonorgestrel oral increases levels of maraviroc by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.metforminlevonorgestrel oral decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.mifepristonemifepristone decreases effects of levonorgestrel oral by pharmacodynamic antagonism. Use Caution/Monitor. Backup contraceptive method recommended.mitotanemitotane decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.mycophenolatemycophenolate decreases levels of levonorgestrel oral by unspecified interaction mechanism. Use Caution/Monitor. Consider additional birth control methods during mycophenolate administration.nafcillinnafcillin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nevirapinenevirapine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.oxcarbazepineoxcarbazepine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.pentobarbitalpentobarbital decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.phenobarbitalphenobarbital decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.phenytoinphenytoin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.pitolisantpitolisant will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Pitolisant is a borderline/weak inducer of CYP3A4. Monitor sensitive CYP3A4 substrates for reduced effectiveness if coadministered.primidoneprimidone decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ribociclibribociclib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifabutinrifabutin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifampinrifampin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifapentinerifapentine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rucaparibrucaparib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.secobarbitalsecobarbital will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.siltuximabsiltuximab, levonorgestrel oral. Other (see comment). Use Caution/Monitor. Comment: CYP450 activity in the liver is down regulated by infection and inflammation stimuli including cytokines (eg, IL-6); inhibition of IL-6 by siltuximab may restore CYP450 enzymatic activity; caution if coadministered with CYP substrates that have a narrow therapeutic index.St John's WortSt John's Wort decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.stiripentolstiripentol, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.tazemetostattazemetostat will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.tecovirimattecovirimat will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.teriflunomideteriflunomide increases levels of levonorgestrel oral by unknown mechanism. Use Caution/Monitor.tesamorelintesamorelin will decrease the level or effect of levonorgestrel oral by altering metabolism. Use Caution/Monitor. Use alternative contraceptiontopiramatetopiramate decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.valoctocogene roxaparvoveclevonorgestrel oral and valoctocogene roxaparvovec both increase Other (see comment). Use Caution/Monitor. Medications that may cause hepatotoxicity when combined with valoctogene roxaparvovec may potentiate the risk of elevated liver enzymes. Closely monitor these medications and consider alternative medications in case of potential drug interactions.Minor (6)acetazolamideacetazolamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.anastrozoleanastrozole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cyclophosphamidecyclophosphamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.enasidenibenasidenib, levonorgestrel oral. unknown mechanism. Minor/Significance Unknown. Coadministration of enasidenib may increase or decrease the concentrations of combined hormonal contraceptives. Clinical significance of this interaction is unknown.larotrectiniblarotrectinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.levoketoconazolelevoketoconazole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.abametapirSerious - Use Alternative (1)abametapir will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.acetazolamideMinor (1)acetazolamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.albiglutideMonitor Closely (1)levonorgestrel oral decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.amobarbitalMonitor Closely (1)amobarbital will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.anastrozoleMinor (1)anastrozole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.antithrombin alfaSerious - Use Alternative (1)levonorgestrel oral, antithrombin alfa. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.antithrombin IIISerious - Use Alternative (1)levonorgestrel oral, antithrombin III. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.apalutamideSerious - Use Alternative (1)apalutamide will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.argatrobanSerious - Use Alternative (1)levonorgestrel oral, argatroban. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.atazanavirMonitor Closely (1)atazanavir, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Atazanavir may increase or decrease levels of levonorgestrel oral. Use alternatives if available. .belzutifanSerious - Use Alternative (1)belzutifan will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of belzutifan with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective nonhormonal contraception. Based on animal studies, belzutifan can cause fetal harm.bemiparinSerious - Use Alternative (1)levonorgestrel oral, bemiparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.bivalirudinSerious - Use Alternative (1)levonorgestrel oral, bivalirudin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.bosentanMonitor Closely (1)bosentan decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.brigatinibSerious - Use Alternative (1)brigatinib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Brigatinib induces CYP3A4 in vitro. Coadministration of hormonal contraceptives with brigatinib can result in decreased concentrations and loss of efficacy. Brigatinib can cause fetal harm. Women should use an effective nonhormonal method of contraception during treatment and for at least 4 months after the last brigatinib dose.calaspargase pegolSerious - Use Alternative (1)calaspargase pegol, levonorgestrel oral. unknown mechanism. Avoid or Use Alternate Drug. Due to the potential for an indirect interaction between calaspargase pegol and oral contraceptives, concomitant use of these drugs is not recommended. Use another non-oral contraceptive method for females of childbearing potential.carbamazepineMonitor Closely (1)carbamazepine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cenobamateMonitor Closely (2)cenobamate will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate. cenobamate will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Advise women to use additional or alternative non-hormonal birth control when concomitantly using cenobamate with oral contraceptives.ceritinibMonitor Closely (1)ceritinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.clobazamMonitor Closely (1)clobazam will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clobazam is a weak CYP3A4 inducer; effectiveness of hormonal contraceptives may be diminished when given concurrently with clobazam. Additional non-hormonal forms of contraception are recommended.crofelemerMonitor Closely (1)crofelemer increases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.cyclophosphamideMinor (1)cyclophosphamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cyclosporineMonitor Closely (1)levonorgestrel oral, cyclosporine. Either increases levels of the other by decreasing metabolism. Use Caution/Monitor. Combined oral contraceptives containing EE may inhibit the metabolism and increase plasma concentrations of cyclosporine.dabrafenibMonitor Closely (1)dabrafenib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.dalteparinSerious - Use Alternative (1)levonorgestrel oral, dalteparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.dexamethasoneMonitor Closely (1)dexamethasone decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.efavirenzMonitor Closely (1)efavirenz decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.elagolixMonitor Closely (1)elagolix decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.Serious - Use Alternative (1)levonorgestrel oral decreases effects of elagolix by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Based on the mechanism of action of elagolix, estrogen-containing contraceptives are expected to reduce elagolix efficacy. Effects of progestin-only contraceptives on the efficacy of elagolix is unknown. Advise women to use nonhormonal contraceptives during treatment with elagolix and for 1 week after discontinuing elagolix.enasidenibMinor (1)enasidenib, levonorgestrel oral. unknown mechanism. Minor/Significance Unknown. Coadministration of enasidenib may increase or decrease the concentrations of combined hormonal contraceptives. Clinical significance of this interaction is unknown.encorafenibMonitor Closely (1)encorafenib, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.enoxaparinSerious - Use Alternative (1)levonorgestrel oral, enoxaparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.enzalutamideMonitor Closely (1)enzalutamide decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.eslicarbazepine acetateSerious - Use Alternative (1)eslicarbazepine acetate will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional or alternative nonhormonal birth control.etravirineMonitor Closely (1)etravirine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.exenatide injectable solutionMonitor Closely (1)levonorgestrel oral, exenatide injectable solution. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before