Grieve's classic 'A Modern Herbal':

The leaves, bark, flowers and kernels have medicinal virtue. Both the leaves and bark are still employed for their curative powers. They have demulcent, sedative, diuretic and expectorant action. An infusion of 1/2 oz. of the bark or 1 oz. of the dried leaves to a pint of boiling water has been found almost a specific for irritation and congestion of the gastric surfaces. It is also used in whooping cough, ordinary coughs and chronic bronchitis, the dose being from a teaspoonful to a wineglassful as required.

King's American Dispensatory.
by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D., 1898.

Peach leaves in infusion have been recommended in morbid irritability of the bladder and urethra, pertussis, ischuria, hematuria, and nausea, as well as in all inflammations of the stomach and abdomen. They act as a sedative in doses of a tablespoonful every hour or two, of the cold infusion; in larger doses they slightly act upon the bowels, and are said to have been useful in removing worms. Amygdalus is the remedy for irritation and congestion of the gastric surfaces. It is a very valuable agent in gastritis to control the vomiting and allay the extreme irritability of the stomach.

The Dispensatory of the United States of America.
edited by Joseph P. Remington, Horatio C. Wood and others, 1918.

The leaves of the peach are said to be laxative, and have also been used with asserted advantage in whooping cough, irritability of the bladder, etc. The dried leaves may be employed (an ounce to a pint of hot water) in infusion. The flowers of the peach are affirmed to be laxative and vermicidal, in half-fluid-ounce (15 mils) doses when fresh, given in the form of syrup.