Why is silver nitrate used in on medicine?

Silver nitrate is a chemical compound with chemical formula AgNO3. This nitrate of silver is a light-sensitive ingredient in photographic film and is a poisonous, corrosive compound. Silver nitrate crystals can be produced by dissolving silver in nitric acid and evaporating the solution. The compound notably stains skin a greyish or black color that is made visible after exposure to sunlight.



1. AgNO3 Cautery

Silver nitrate(CAS.NO:7761-88-8) can be used in a medical environment as a chemical cauterizing agent and medicinal caustic. A typical applicator is composed of 75% silver nitrate with 25% potassium nitrate. As the silver nitrate contacts with water (in the blood) the compound goes into solution forming nitric acid. The acid subsequently is responsible for the cautery effect. As mentioned above this will typically result in a black or greyish staining of the skin. This staining is caused by the accumulation of the silver and will typically go away as the body rids itself of the mineral.

2. Possible toxicity

1) Silver nitrate when used topically has been noted to cause irritation, redness.

2) The main toxic effect of topical silver nitrate is a generalized gray pigmentation of the skin called argyria. This is very rare with chronic topical use and typically occurs more frequently with chronic systemic absorption. On average, 3.8 grams of silver nitrate given orally can cause argyria to begin to be observed.

3) Silver nitrate is mainly considered a poison with ingestion due to the corrosive nature of the compound. If ingested, silver nitrate can cause potentially fatal gastroenteritis and gastrointestinal bleed. In toxicity studies, 29mg/kg administered to humans via an unknown route caused no fatalities, however 50mg/kg given orally to mice was lethal to 50% of the subjects.


3. Effect

Silver nitrate is a powerful chemical germicide and, on contact with living tissue,

1) "Toughened silver nitrate" and "Lunar caustic" are terms to describe the combination of silver nitrate with potassium nitrate

2) Exposure to light causes the silver in the tip to turn brown, but does not affect its therapeutic action

3) Moisture has a deteriorating effect on the tip (can make it break or loosen from the applicator)

4) Improper use of silver nitrate can cause chemical burns (it is a caustic compound)

* Use in neonates (as on the umbilicus) should be of short duration

*  Do not use in the eyes

4. Indications

1) Skin

*Cauterization of wounds an sluggish ulcers

*Removal of granulation tissue and warts


2) Mucous membranes

*Oral ulcers and apthae

*Control of epistaxis by direct application to hemorrhagic site