Grieve’s classic ‘A Modern Herbal’:

Both the dark and the pale Catechu are employed in medicine, the former is more astringent, the latter, being sweeter, is less disagreeable.

It depends almost entirely for its virtues upon the tannic acid it contains and is hence employed as an astringent to overcome relaxation of mucous membranes in general.

An infusion can be employed to stop nosebleeding, and is also employed as an injection for uterine haemorrhage, leucorrhoea and gonorrhoea.

Externally, it is applied in the form of powder, to boils, ulcers and cutaneous eruptions, and also used for the same purposes mixed with other ingredients, in an ointment.

A small piece, held in the mouth and allowed slowly to dissolve, is an excellent remedy in relaxation of the uvula and simple pharyngitis.

In powder, applied to spongy gums, it often proves of use and has been recommended as a dentifrice with powdered charcoal, myrrh, etc.

The pharmaceutical preparations are: Powdered Catechu, dose 5 to 15 grains; Compound Powder of Catechu, B.P., dose 10 to 40 grains; Tincture of Catechu, B.P., dose 1/2 to 1 drachm; Comp. Tincture, U.S.P., dose 1 drachm. Catechu Lozenges are also official preparations in both the British and United States Pharmacopoeias.

King's American Dispensatory, 1898:

Catechu possesses strong astringent properties. It is used for arresting mucous discharges when excessive, for removing relaxation or congestion of mucous membranes, and for checking hemorrhages.

In chronic diarrhoea, chronic catarrh, colliquative diarrhoea, and chronic dysentery, it has proved beneficial, especially when combined with opium. As a local application, it is a valuable agent for removing cynanche tonsillaris, aphthous ulcerations of the mouth, elongation of the uvula, and relaxation and congestion of the mucous membrane of the fauces, especially of the kind to which public singers are subject; it is also useful in congestion, tenderness and sponginess of the gums, particularly when the result of mercurial ptyalism.

Powdered catechu may be given in a dose of from 5 to 20 grains, or more, repeated as often as required; it may be administered in pill form, in syrup, or in gum mucilage. The dose of the tincture is from 20 minims to 1/2 fluid ounce.

American Materia Medica (Ellingwood), 1919:

A tonic astringent indicated in diarrheas where the discharges are serous, very watery in character-large fluid discharges, with mucus. It will relieve intestinal hemorrhage, when the above diarrheas are present, and the mucous membranes are relaxed, and out of tone. If combined with stimulant tonics or aromatics it is more serviceable. With special uterine tonics, it will be found advantageous in menorrhagia.