Isoniazid has 78 known drug interactions based on U.S. FDA drug labeling data. Of these, 1 are contraindicated combinations that should be avoided entirely. 8 are classified as major interactions requiring close medical supervision. Notable interactions include combinations with Bacillus Calmette-Guerin, Acetaminophen, Carbamazepine. Patients taking Isoniazid should inform their healthcare provider of all current medications — including over-the-counter drugs and supplements — to avoid potentially harmful combinations. Data sourced from OpenFDA and the NIH National Library of Medicine.
- Total
- 78
- Contraindicated
- 1
- Major
- 8
- Moderate
- 68
Contraindicated (1)
- Isoniazid + Bacillus Calmette-Guerin— Antituberculosis drugs should not be used to prevent or treat local irritative toxicities of TICE BCG, as these are not …
Major (8)
- Isoniazid + Acetaminophen— Isoniazid induces P-450IIE1 enzyme, increasing conversion of acetaminophen to toxic metabolites and potentiating hepatot…
- Isoniazid + Carbamazepine— Isoniazid slows metabolism and increases serum levels of carbamazepine, requiring monitoring for toxicity signs and dosa…
- Isoniazid + Insulin Glargine— May decrease blood glucose lowering effect of LANTUS. Dosage increases and increased glucose monitoring may be required.
- Isoniazid + Itraconazole— Potent CYP3A4 enzyme inducer that may decrease itraconazole bioavailability and efficacy. Avoid use 2 weeks before and d…
- Isoniazid + Ketoconazole— Ketoconazole AUC is decreased by up to 88% when combined with isoniazid and rifampin after 5 months of concurrent therap…
- Isoniazid + Phenytoin— Isoniazid may increase serum levels of phenytoin, requiring dosage adjustment to avoid phenytoin intoxication.
- Isoniazid + Rifampin— Concomitant use increases potential for hepatotoxicity. Patients should be monitored closely.
- Isoniazid + Theophylline— Concurrent isoniazid and theophylline administration may cause elevated plasma theophylline levels. Close monitoring and…
Moderate (68)
- Isoniazid + Acarbose— Isoniazid produces hyperglycemia and may lead to loss of blood glucose control in patients receiving Acarbose. Close obs…
- Isoniazid + Acetaminophen, Caffeine, Dihydrocodeine Bitartrate— Increases potential for acetaminophen hepatotoxicity.
- Isoniazid + Alogliptin And Metformin Hydrochloride— May produce hyperglycemia and lead to loss of glycemic control.
- Isoniazid + Alprazolam— Possible drug interaction with alprazolam based on clinical studies in other benzodiazepines. Caution recommended during…
- Isoniazid + Ascorbic Acid, Vitamin A Palmitate, Cholecalciferol, Thiamine Hydrochloride, Riboflavin-5 Phosphate Sodium, Pyridoxine Hydrochloride, Niacinamide, Dexpanthenol, Alpha-Tocopherol Acetate, Vitamin K1, Folic Acid, Biotin, Cyanocobalamin— Concomitant administration may increase pyridoxine requirements.
- Isoniazid + Betamethasone Sodium Phosphate, Betamethasone Acetate, Lidocaine, Iodixanol, Povidine Iodine— Serum concentrations of isoniazid may be decreased by corticosteroids.
- Isoniazid + Carbidopa— May reduce the therapeutic effects of levodopa; patients should be carefully observed for loss of therapeutic response.
- Isoniazid + Carbidopa And Levodopa— May reduce the therapeutic effects of levodopa; patients should be carefully observed for loss of therapeutic response.
- Isoniazid + Carbidopa Tablets— May reduce therapeutic effects of levodopa; patients should be carefully observed for loss of therapeutic response.
- Isoniazid + Carbidopa, Levodopa And Entacapone— May reduce therapeutic effects of levodopa; dose increase may be necessary.
- Isoniazid + Dapagliflozin And Metformin Hydrochloride— Produces hyperglycemia and may lead to loss of glycemic control when used with XIGDUO XR.
- Isoniazid + Depo-Medrol, Lidocaine, Isopropyl Alcohol— Serum concentrations of isoniazid may be decreased by corticosteroids.
- Isoniazid + Dexamethasone— Serum concentrations of isoniazid may be decreased by dexamethasone.
- Isoniazid + Dexamethasone 1.5 Mg— Serum concentrations of isoniazid may be decreased when used with dexamethasone.
- Isoniazid + Dexamethasone Intensol— Serum concentrations of isoniazid may be decreased by dexamethasone.
- Isoniazid + Disulfiram— Patients should be observed for unsteady gait or marked changes in mental status. Disulfiram should be discontinued if s…
- Isoniazid + Empagliflozin, Metformin Hydrochloride— May produce hyperglycemia and lead to loss of glycemic control; monitor closely.
- Isoniazid + Ertugliflozin And Metformin Hydrochloride— May produce hyperglycemia and lead to loss of glycemic control; close monitoring recommended.
- Isoniazid + Estazolam— Significant CYP3A inhibitor; estazolam should be used with caution and appropriate dosage reduction may be needed.
- Isoniazid + Folic Acid— Isoniazid reduces folate utilization through metabolic disruption.
- Isoniazid + Foscarbidopa/Foslevodopa— May reduce the effectiveness of foslevodopa. Monitor patients for worsening Parkinson's symptoms.
- Isoniazid + Fosphenytoin Sodium— May increase phenytoin serum levels; monitoring of phenytoin levels recommended.
- Isoniazid + Glibenclamide— Isoniazid may produce hyperglycemia and lead to loss of control of glyburide. Patients should be closely observed for lo…
- Isoniazid + Glimepiride— May reduce glucose-lowering effect of glimepiride, leading to worsening glycemic control.
- Isoniazid + Glipizide— Isoniazid may produce hyperglycemia and lead to loss of glycemic control. Patient should be observed closely for loss of…
- Isoniazid + Glipizide And Metformin Hydrochloride— Isoniazid may produce hyperglycemia and lead to loss of blood glucose control. Patient should be closely observed for lo…
- Isoniazid + Glyburide And Metformin Hydrochloride— Isoniazid tends to produce hyperglycemia and may lead to loss of blood glucose control. Close observation required.
- Isoniazid + Hydrocortisone Acetate— Serum concentrations of isoniazid may be decreased by corticosteroids.
- Isoniazid + Hydrocortisone Sodium Succinate— Serum concentrations of isoniazid may be decreased when used with corticosteroids.
- Isoniazid + Insulin Aspart Injection— May decrease the blood glucose lowering effect. Dose adjustment and increased glucose monitoring required.
- Isoniazid + Insulin Aspart-Szjj— May decrease blood glucose lowering effect. Dose adjustment and increased glucose monitoring may be required.
- Isoniazid + Insulin Degludec— May decrease blood glucose lowering effect. Dosage increases and increased glucose monitoring may be required.
- Isoniazid + Insulin Degludec And Liraglutide— May decrease blood glucose-lowering effect; dosage increases and increased glucose monitoring may be required.
- Isoniazid + Insulin Detemir— May decrease blood glucose lowering effect of insulin detemir. Dosage increases and increased glucose monitoring may be …
- Isoniazid + Insulin Glargine And Lixisenatide— May decrease the blood glucose lowering effect. Dose increases and increased glucose monitoring may be required.
- Isoniazid + Insulin Glargine-Aglr— May decrease blood glucose lowering effect. Dosage increases and increased glucose monitoring may be required.
- Isoniazid + Insulin Glargine-Yfgn— May decrease blood glucose lowering effect. Dosage increases and increased glucose monitoring may be required.
- Isoniazid + Insulin Glulisine— May decrease blood glucose lowering effect. Dose adjustment and increased glucose monitoring may be required.
- Isoniazid + Insulin Human— May decrease blood glucose lowering effect; dose adjustment and increased glucose monitoring may be required.
- Isoniazid + Insulin Icodec-Abae— May decrease blood glucose lowering effect of Awiqli. Dose increases and increased glucose monitoring may be required.
- Isoniazid + Insulin Lispro— May decrease blood glucose lowering effect; dose adjustment and increased glucose monitoring required.
- Isoniazid + Insulin Lispro-Aabc— May decrease blood glucose lowering effect. Dose increases and increased glucose monitoring may be required.
- Isoniazid + Kenalog— Serum concentrations of isoniazid may be decreased by corticosteroids.
- Isoniazid + Levodopa— Isoniazid may reduce the effectiveness of levodopa. Monitor patients for worsening Parkinson's symptoms.
- Isoniazid + Linagliptin And Metformin Hydrochloride— Isoniazid may produce hyperglycemia and lead to loss of glycemic control. Close monitoring of glycemic control is recomm…
- Isoniazid + Marcaine, Lidocaine, Kenalog, Povidone Iodine— Serum concentrations of isoniazid may be decreased by corticosteroids.
- Isoniazid + Metformin— Produces hyperglycemia and may lead to loss of glycemic control when used with metformin.
- Isoniazid + Metformin Er 500 Mg— May produce hyperglycemia and lead to loss of glycemic control. Monitor patient closely for loss of blood glucose contro…
- Isoniazid + Metformin Hydrochloride— Drugs that produce hyperglycemia and may lead to loss of glycemic control; monitor blood glucose.
- Isoniazid + Metformin Hydrochloride Extended-Release Tablets— May produce hyperglycemia and lead to loss of glycemic control during metformin therapy; monitor blood glucose.
- Isoniazid + Metformin Hydrochloride Tablet— May produce hyperglycemia and lead to loss of glycemic control when used with metformin.
- Isoniazid + Methylprednisolone— Serum concentrations of isoniazid may be decreased when used with corticosteroids.
- Isoniazid + Methylprednisolone Acetate— Serum concentrations of isoniazid may be decreased when used with corticosteroids.
- Isoniazid + Methylprednisolone Acetate, Lidocaine Hydrochloride, Povidine Iodine, Isopropyl Alcohol— Serum concentrations of isoniazid may be decreased when used concomitantly with corticosteroids.
- Isoniazid + Methylprednisolone Sodium Succinate— Serum concentrations of isoniazid may be decreased when used with corticosteroids.
- Isoniazid + Multiple Vitamins Injection— Concomitant administration may increase pyridoxine requirements.
- Isoniazid + Nimodipine— Moderate CYP3A4 inhibitor that may increase nimodipine plasma concentration and blood pressure lowering effect. Blood pr…
- Isoniazid + Phenytoin Sodium— May increase phenytoin serum levels; monitoring of phenytoin levels recommended.
- Isoniazid + Prednisolone Sodium Phosphate— Serum concentrations of isoniazid may be decreased by corticosteroid co-administration.
- Isoniazid + Prednisone— Serum concentrations of isoniazid may be decreased by concurrent corticosteroid use.
- Isoniazid + Propranolol Hydrochloride— CYP1A2 substrate/inhibitor that may increase blood levels and/or toxicity of propranolol.
- Isoniazid + Repaglinide— May decrease blood glucose lowering effect of repaglinide. Dose increases and increased glucose monitoring may be requir…
- Isoniazid + Safinamide Mesylate— Has monoamine oxidase inhibiting activity; monitor for hypertension and reaction to dietary tyramine.
- Isoniazid + Sitagliptin And Metformin Hydrochloride— May produce hyperglycemia and lead to loss of glycemic control. Monitor blood glucose closely during concomitant use.
- Isoniazid + Triamcinolone Acetonide— Serum concentrations of isoniazid may be decreased by corticosteroids.
- Isoniazid + Triamcinolone Acetonide Extended-Release Injectable Suspension— Serum concentrations of isoniazid may be decreased with concurrent corticosteroid use.
- Isoniazid + Triazolam— Coadministration increased maximum plasma concentration by 20%, decreased clearance by 42%, and increased half-life by 3…
- Isoniazid + Valproate— Isoniazid may increase plasma levels of valproate. Plasma valproate concentration should be monitored and dosage adjustm…