Substances used as astringents are allantoin, bismuth oxide, bismuth subgallate, witch hazel (hamamelis) extract, Peru balsam and zinc oxide.

Astringents coagulate protein in skin and mucous membrane cells to form a superficial protective layer. By reducing the secretion of mucus and intracellular contents from damaged cells, they help relieve local irritation and inflammation. Some astringent substances, such as zinc oxide and bismuth salts, also provide a mechanical protective barrier on the surface of damaged skin. Peru balsam has additional mild antiseptic properties.

Hydrocortisone acetate
Hydrocortisone is a naturally-occurring glucocorticoid secreted by the adrenal cortex and is widely used as a topical anti-inflammatory agent. Its action is thought to be exerted through two mechanisms: stabilisation of lysosomal membranes, reducing the release of inflammatory lytic enzymes; and inhibition of phospholipase A, which reduces the release of arachidonic acid from phospholipids in cell membranes, with a consequent inhibition of prostaglandin synthesis.

Use of haemorrhoidal preparations containing hydrocortisone is subject to restrictions. They should not be used:

• By patients under 18 years of age
• During pregnancy or breastfeeding
• For more than seven days
• In the presence of infected skin lesions
• More than three or four times in 24 hours.