Thyme oil
Inflammation causes white blood cells to produce elastase, which breaks down elastin, the macromolecule that keeps tissues tight. Enter thymol, a thyme-oil derivative that blocks elastase production.

Methylparaben
Occurring naturally in blueberries, this antifungal agent degrades easily in UV light, forming oxides that can damage skin. Good thing we use this stuff where the sun doesn’t shine.

Phenylephrine HCl
Applied locally, this vasoconstrictor sends a message to your neurons to constrict blood vessels and contract the sphincter. It’s also used in nasal decongestants. We don’t recommend Preparation H for a stuffy nose.

Light mineral oil
Hemorrhoids are swollen and inflamed veins. Friction, as well as periodic contact with, uh, toxic sludge, makes them burn like Catholic guilt. Mineral oil coats the area, reducing friction. It also thins the petrolatum, making the product easier to put on.

Propylparaben
Take benzoic acid, add another -OH group at the bottom and an alkyl group (C3H5 in this case) at the top and you’ve got a paraben, an inexpensive preservative.

Shark liver oil
Harvested from the livers of sharks that live in cold, deep water, this serves as a barrier against contamination and as a lubricant to cut down on friction and keep things, well, moving along smoothly.

Benzoic acid
A simple six-carbon ring attached to a carboxyl (-COOH) group, benzoic acid penetrates microbial cell membranes, killing any creature that might feed on Preparation H’s biological oils and waxes.

Authors: Patrick Di Justo

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