narrow therapeutic index, consider monitoring for therapeutic effect.vemurafenibvemurafenib decreases levels of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Concomitant use of vemurafenib with agents with narrow therapeutic windows is not recommended as vemurafenib may alter their concentrations. If coadministration cannot be avoided, use caution and consider dose reduction of concomitant CYP1A2 substrate drug.verapamilverapamil will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.verapamil will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.voriconazolevoriconazole will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.zafirlukastzafirlukast will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.zileutonzileuton will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Minor (29)acetazolamideacetazolamide will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.amiodaroneamiodarone increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.anastrozoleanastrozole will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cetirizinetheophylline increases levels of cetirizine by decreasing elimination. Minor/Significance Unknown.cilostazoltheophylline increases levels of cilostazol by decreasing metabolism. Minor/Significance Unknown.clarithromycinclarithromycin increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.clinafloxacinclinafloxacin increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.cyclophosphamidecyclophosphamide will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dexlansoprazoledexlansoprazole increases toxicity of theophylline by Other (see comment). Minor/Significance Unknown. Comment: Prolonged use of proton pump inhibitors can cause hypochlorhydria, which in turn causes peristalsis in small intestine to increase and peristalsis in the proximal colon to decrease; monitor for toxicity.disulfiramdisulfiram increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.elderberryelderberry increases effects of theophylline by decreasing metabolism. Minor/Significance Unknown.esomeprazoleesomeprazole increases toxicity of theophylline by Other (see comment). Minor/Significance Unknown. Comment: Prolonged use of proton pump inhibitors can cause hypochlorhydria, which in turn causes peristalsis in small intestine to increase and peristalsis in the proximal colon to decrease; monitor for toxicity.lansoprazolelansoprazole increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.lansoprazole increases toxicity of theophylline by Other (see comment). Minor/Significance Unknown. Comment: Prolonged use of proton pump inhibitors can cause hypochlorhydria, which in turn causes peristalsis in small intestine to increase and peristalsis in the proximal colon to decrease; monitor for toxicity.larotrectiniblarotrectinib will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.levocetirizinetheophylline increases levels of levocetirizine by decreasing elimination. Minor/Significance Unknown.levothyroxinelevothyroxine decreases levels of theophylline by increasing elimination. Minor/Significance Unknown.liothyronineliothyronine decreases levels of theophylline by increasing elimination. Minor/Significance Unknown.lithiumtheophylline decreases levels of lithium by increasing renal clearance. Minor/Significance Unknown.omeprazoleomeprazole will decrease the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.omeprazole increases toxicity of theophylline by Other (see comment). Minor/Significance Unknown. Comment: Prolonged use of proton pump inhibitors can cause hypochlorhydria, which in turn causes peristalsis in small intestine to increase and peristalsis in the proximal colon to decrease; monitor for toxicity.pentoxifyllinepentoxifylline increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.phytoestrogensphytoestrogens increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.phytoestrogens increases levels of theophylline by decreasing elimination. Minor/Significance Unknown.propafenonepropafenone increases levels of theophylline by decreasing renal clearance. Minor/Significance Unknown.pyrantel pamoatepyrantel pamoate increases levels of theophylline by unspecified interaction mechanism. Minor/Significance Unknown.pyridoxinetheophylline decreases levels of pyridoxine by altering metabolism. Minor/Significance Unknown.pyridoxine (Antidote)theophylline decreases levels of pyridoxine (Antidote) by altering metabolism. Minor/Significance Unknown.ribociclibribociclib will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.thyroid desiccatedthyroid desiccated decreases levels of theophylline by increasing elimination. Minor/Significance Unknown.ticlopidineticlopidine increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.zafirlukasttheophylline decreases levels of zafirlukast by unknown mechanism. Minor/Significance Unknown.abametapirSerious - Use Alternative (2)abametapir will increase the level or effect of theophylline 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. abametapir will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP1A2 substrates. If not feasible, avoid use of abametapir.acebutololMonitor Closely (1)acebutolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.acetazolamideMinor (1)acetazolamide will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.activated charcoalMonitor Closely (1)activated charcoal decreases levels of theophylline by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.adenosineMonitor Closely (1)theophylline decreases effects of adenosine by pharmacodynamic antagonism. Use Caution/Monitor.allopurinolSerious - Use Alternative (1)allopurinol increases levels of theophylline by decreasing metabolism. Avoid or Use Alternate Drug.amifampridineMonitor Closely (1)theophylline increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.amiodaroneMinor (1)amiodarone increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.amobarbitalMonitor Closely (2)amobarbital will decrease the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. amobarbital will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.anastrozoleMinor (1)anastrozole will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.apalutamideSerious - Use Alternative (1)apalutamide will decrease the level or effect of theophylline 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.aprepitantMonitor Closely (1)aprepitant will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.armodafinilMonitor Closely (2)armodafinil will decrease the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. armodafinil will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.artemether/lumefantrineMonitor Closely (1)artemether/lumefantrine will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.atazanavirMonitor Closely (1)atazanavir will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.atenololMonitor Closely (1)atenolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.betaxololMonitor Closely (1)betaxolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.bisoprololMonitor Closely (1)bisoprolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.blinatumomabMonitor Closely (1)blinatumomab increases levels of theophylline by decreasing metabolism. Modify Therapy/Monitor Closely. Treatment initiation causes transient release of cytokines that may suppress CYP450 enzymes; highest drug-drug interaction risk is during the first 9 days of the first cycle and the first 2 days of the 2nd cycle in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index.bosentanMonitor Closely (1)bosentan will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.bremelanotideSerious - Use Alternative (1)bremelanotide will decrease the level or effect of theophylline by Other (see comment). Avoid or Use Alternate Drug. Bremelanotide may slow gastric emptying and potentially reduces the rate and extent of absorption of concomitantly administered oral medications. Avoid use when taking any oral drug that is dependent on threshold concentrations for efficacy. Interactions listed are representative examples and do not include all possible clinical examples.brodalumabMonitor Closely (1)brodalumab, theophylline. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, brodalumab could normalize the formation of CYP450 enzymes. Upon initiation or discontinuation of brodalumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.budesonideMonitor Closely (1)budesonide will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.bupropionSerious - Use Alternative (1)theophylline increases toxicity of bupropion by unspecified interaction mechanism. Avoid or Use Alternate Drug. May lower seizure threshold; keep bupropion dose as low as possible.butabarbitalMonitor Closely (2)butabarbital will decrease the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. butabarbital will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.butalbitalMonitor Closely (2)butalbital will decrease the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. butalbital will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cannabidiolMonitor Closely (1)cannabidiol, theophylline. affecting hepatic enzyme CYP1A2 metabolism. Modify Therapy/Monitor Closely. Owing to the potential for both CYP1A2 induction and inhibition with the coadministration of CYP1A2 substrates and cannabidiol, consider reducing dosage adjustment of CYP1A2 substrates as clinically appropriate.carbamazepineMonitor Closely (1)carbamazepine will decrease the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (2)carbamazepine will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. theophylline decreases levels of carbamazepine by increasing metabolism. Avoid or Use Alternate Drug.carvedilolMonitor Closely (1)carvedilol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.celiprololMonitor Closely (1)celiprolol, theophylline. Other (see comment). Use Caution/Monitor. Comment: Beta blockers (esp. non selective) antagonize theophylline effects, while at the same time increasing theophylline levels and toxicity (mechanism: decreased theophylline metabolism). Smoking increases risk of interaction.cenobamateMonitor Closely (2)cenobamate, theophylline. Either increases effects of the other by sedation. Use Caution/Monitor. cenobamate will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.ceritinibSerious - Use Alternative (1)ceritinib increases levels of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concurrent use of CYP3A substrates known to have narrow therapeutic indices or substrates primarily metabolized by CYP3A during treatment with ceritinib; if use of these medications is unavoidable, consider dose.cetirizineMinor (1)theophylline increases levels of cetirizine by decreasing elimination. Minor/Significance Unknown.cigarette smokingMonitor Closely (1)cigarette smoking will decrease the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.cilostazolMinor (1)theophylline increases levels of cilostazol by decreasing metabolism. Minor/Significance Unknown.cimetidineMonitor Closely (1)cimetidine will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)cimetidine will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.ciprofloxacinSerious - Use Alternative (2)ciprofloxacin will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. Concomitant use of theophylline and ciprofloxacin has decreased theophylline clearance and increased plasma levels and symptoms of toxicity. Serious and fatal reactions have included cardiac arrest, seizure, status epilepticus, and respiratory failure. If concomitant use cannot be avoided, monitor theophylline levels and adjust dosage as needed. ciprofloxacin will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Concomitant use of theophylline and ciprofloxacin has decreased theophylline clearance and increased plasma levels and symptoms of toxicity. Serious and fatal reactions have included cardiac arrest, seizure, status epilepticus, and respiratory failure. If concomitant use cannot be avoided, monitor theophylline levels and adjust dosage as needed.clarithromycinSerious - Use Alternative (1)clarithromycin will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)clarithromycin increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.clinafloxacinMinor (1)clinafloxacin increases levels of theophylline by decreasing metabolism. Minor/Significance Unknown.cobicistatMonitor Closely (1)cobicistat will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.conivaptanMonitor Closely (1)conivaptan will increase the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cortisoneMonitor Closely (1)cortisone will decrease the level or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.crizotinibMonitor Closely (1)crizotinib increases levels