Guanethidine
Guanethidine is an antihypertensive medication that works by depleting norepinephrine from nerve endings, reducing the ability of sympathetic nerves to maintain vascular tone. It was historically used for treating moderate to severe hypertension, though it has largely been replaced by more modern agents with better side effect profiles.
Guanethidine is an older antihypertensive that lowers blood pressure by reducing sympathetic nervous system activity.
Key facts at a glance
- ATC
- C02CC02
- RxNorm
- 5036
- Generic
- Guanethidine
- Class
- atc-c02
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- ophthalmic, oral
- Forms
- solution, tablet
- Regions
- US, EU, CN, JP
- Monitoring
- —
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Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Primarily used for managing moderate to severe hypertension when other treatments are inadequate. It may also have been used in certain cases of glaucoma and catecholamine-secreting tumors.
Guanethidine inhibits norepinephrine release from sympathetic nerve terminals by interfering with the vesicular storage and transport of catecholamines. This leads to decreased peripheral vascular resistance and reduced blood pressure.
Due to its side effect profile including orthostatic hypotension, diarrhea, and sexual dysfunction, guanethidine is rarely used today. It may interact with tricyclic antidepressants, MAO inhibitors, and sympathomimetic amines. Not recommended for use in patients with pheochromocytoma or heart failure.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy