# Litharge

**Lithargyrum*, “silver stone”*

**Known today as.** Lead monoxide, a byproduct of refining silver.

Kind: Mineral  
Poisoning: Mercury, arsenic, lead, and antimony (https://thethinkingpress.org/materia-medica/poisons/heavy-metal)  
Toxic: yes

> **Caution.** Poisonous.

## What was it used for?

The base of plasters, above all the diachylon plaster, and of drying ointments.

## What does modern science say?

Poisonous; its plasters were used into the twentieth century.

## Pharmacognosy and toxicology

- **lead oxide**: 

**Mechanism.** As white lead.

**Dose.** Chronic.

**Standing.** No medicinal use; the lead plaster of the pharmacopoeias is gone.

## What did the older authorities say?

**Menecrates.** The diachylon plaster of litharge and oil was credited to Menecrates, physician to the emperor Tiberius.

## Sources

- Dioscorides, *De materia medica* V.
- Needleman, H. (2004). *Annual Review of Medicine* 55.

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*Litharge.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-09-25. The Thinking Press. https://thethinkingpress.org/materia-medica/litharge

Historical description, not medical advice.