Guanethidine has 45 known drug interactions based on U.S. FDA drug labeling data. Of these, 1 are contraindicated combinations that should be avoided entirely. 11 are classified as major interactions requiring close medical supervision. Notable interactions include combinations with Phenelzine Sulfate, Amitriptyline Hydrochloride, Bisoprolol Fumarate. Patients taking Guanethidine 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
- 45
- Contraindicated
- 1
- Major
- 11
- Moderate
- 32
- Minor
- 1
Contraindicated (1)
- Guanethidine + Phenelzine Sulfate— Can produce moderate to severe hypertension due to release of catecholamines. At least two weeks should elapse between M…
Major (11)
- Guanethidine + Amitriptyline Hydrochloride— See WARNINGS section for interaction details with amitriptyline hydrochloride.
- Guanethidine + Bisoprolol Fumarate— Catecholamine-depleting drug that may produce excessive reduction of sympathetic activity when combined with bisoprolol …
- Guanethidine + Bisoprolol Fumarate And Hydrochlorothiazide— Catecholamine-depleting drug that with bisoprolol's beta-adrenergic blocking action may produce excessive reduction of s…
- Guanethidine + Clomipramine Hydrochloride— Tricyclic antidepressants block the pharmacologic effects of guanethidine; such an effect may be anticipated with clomip…
- Guanethidine + Epinephrine— Epinephrine may antagonize neuronal blockade, decreasing antihypertensive effect and requiring increased dosage.
- Guanethidine + Metoprolol Tartrate— Antihypertensive effect may be potentiated by metoprolol, increasing risk of hypotension.
- Guanethidine + Minoxidil— Minoxidil may interact with guanethidine, requiring careful monitoring. See WARNINGS section for detailed interaction in…
- Guanethidine + Nebivolol— Catecholamine-depleting drug; concomitant use may produce excessive reduction of sympathetic activity. Closely monitor p…
- Guanethidine + Nebivolol Hydrochloride— Catecholamine-depleting drug may produce excessive reduction of sympathetic activity when combined with nebivolol's β-bl…
- Guanethidine + Sodium Phosphate, Dibasic, Anhydrous, Potassium Phosphate, Monobasic, And Sodium Phosphate, Monobasic, Monohydrate— Concurrent use with sodium phosphate may result in hypernatremia.
- Guanethidine + Sotalol Hydrochloride— Catecholamine-depleting agent; may produce excessive reduction of resting sympathetic nervous tone, causing hypotension …
Moderate (32)
- Guanethidine + Amphetamine— Gastrointestinal acidifying agent that lowers amphetamine absorption and blood levels, reducing efficacy.
- Guanethidine + Amphetamine Sulfate— Gastrointestinal acidifying agent that lowers amphetamine absorption and blood levels.
- Guanethidine + Clomipramine Hydrochloride Capsules— Tricyclic antidepressants including clomipramine may block the pharmacologic effects of guanethidine.
- Guanethidine + Cyclobenzaprine— Tricyclic antidepressants may block the antihypertensive action of guanethidine.
- Guanethidine + Cyclobenzaprine Hcl Er— Cyclobenzaprine may block the antihypertensive action of guanethidine.
- Guanethidine + Cyclobenzaprine Hydrochloride— Tricyclic antidepressants may block the antihypertensive action of guanethidine.
- Guanethidine + Dextroamphetamine— Gastrointestinal acidifying agent lowers amphetamine absorption and blood levels, reducing efficacy.
- Guanethidine + Dextroamphetamine Saccharate, Amphetamine Aspartate Monohydrate, Dextroamphetamine Sulfate And Amphetamine Sulfate— Acidifying agent that lowers blood levels and efficacy of amphetamines. Dose adjustment may be needed based on clinical …
- Guanethidine + Dextroamphetamine Sulfate— Gastrointestinal acidifying agent that lowers amphetamine absorption and blood levels.
- Guanethidine + Diethylpropion Hydrochloride— Pressor effects are additive; diethylpropion may interfere with antihypertensive efficacy.
- Guanethidine + Ephedrine Sulfate— Ephedrine may inhibit neuron blockage produced by guanethidine, resulting in loss of antihypertensive effectiveness. Mon…
- Guanethidine + Glimepiride— May increase glucose-lowering effect of glimepiride, increasing susceptibility to and/or intensity of hypoglycemia.
- Guanethidine + Glipizide— May mask signs of hypoglycemia in patients taking glipizide.
- Guanethidine + Insulin Aspart Injection— May blunt signs and symptoms of hypoglycemia. Increased frequency of glucose monitoring required.
- Guanethidine + Insulin Aspart-Szjj— May blunt signs and symptoms of hypoglycemia. Increased glucose monitoring may be required.
- Guanethidine + Insulin Degludec— May blunt signs and symptoms of hypoglycemia. Increased glucose monitoring may be required.
- Guanethidine + Insulin Degludec And Liraglutide— May blunt signs and symptoms of hypoglycemia; increased glucose monitoring may be required.
- Guanethidine + Insulin Detemir— May blunt signs and symptoms of hypoglycemia. Increased frequency of glucose monitoring may be required.
- Guanethidine + Insulin Glargine— May blunt signs and symptoms of hypoglycemia; increased glucose monitoring may be required.
- Guanethidine + Insulin Glargine And Lixisenatide— May blunt signs and symptoms of hypoglycemia. Increased frequency of glucose monitoring may be required.
- Guanethidine + Insulin Glargine-Aglr— May blunt signs and symptoms of hypoglycemia. Increased frequency of glucose monitoring may be required.
- Guanethidine + Insulin Glargine-Yfgn— May blunt signs and symptoms of hypoglycemia. Increased glucose monitoring may be required.
- Guanethidine + Insulin Glulisine— May blunt signs and symptoms of hypoglycemia. Increased frequency of glucose monitoring may be required.
- Guanethidine + Insulin Human— May blunt signs and symptoms of hypoglycemia; increased glucose monitoring required.
- Guanethidine + Insulin Icodec-Abae— May blunt signs and symptoms of hypoglycemia. Increased frequency of glucose monitoring required.
- Guanethidine + Insulin Lispro— May blunt signs and symptoms of hypoglycemia; increased glucose monitoring required.
- Guanethidine + Insulin Lispro-Aabc— May blunt signs and symptoms of hypoglycemia. Increased frequency of glucose monitoring may be required.
- Guanethidine + Methamphetamine Hydrochloride— Methamphetamine may decrease the hypotensive effect of guanethidine.
- Guanethidine + Methylphenidate Hydrochloride— Methylphenidate may decrease the hypotensive effect of guanethidine. Use cautiously.
- Guanethidine + Metoprolol— Antihypertensive effect of alpha-adrenergic blocker may be potentiated by metoprolol.
- Guanethidine + Nateglinide— May increase blood-glucose-lowering effect and blunt hypoglycemia symptoms; dose adjustment and monitoring required.
- Guanethidine + Potassium Phosphate, Monobasic And Sodium Phosphate, Monobasic, Anhydrous— Concurrent use with sodium phosphate may result in hypernatremia.
Minor (1)
- Guanethidine + Pindolol— Used together without unexpected adverse interactions in clinical practice.