What Causes Skin Itching After Your Shower?

The most common cause of skin itching after shower is not the shower - that's just water in moderation, it's pretty harmless. It might surprise you to know that one ingredient used in most shampoo, conditioner, toothpaste, shaving cream, shower gel, and 'soap' is also the most common skin irritant! What? Why? Why would companies make skincare products which include an ingredient that causes skin discomfort? The simplest answer: because the consumer demands it.

The problem of skin itching after shower, at bedtime, and during the winter is pretty common. While the time of day, the relative cleanliness, and the time of year seem unrelated, they are actually mostly caused by the same thing: sodium lauryl sulfate.

The connection and the cause is sodium lauryl sulfate, a chemical derived from coconuts. Now you're thinking I'm a kook, a crunchie, a goofball, or an alarmist. I'm not. Let's disprove these unspoken accusations with a bit of science - then we can move on to the solution and you can stop your skin itching after shower.

The Science
Sodium lauryl sulfate is used in laboratory testing to damage the skin's natural barrier function. One of the most important functions of skin is to keep things out. Things like chemicals, bacteria, and viruses would have unfettered entry into our bodies if it weren't for our skin. When a scientist wants to see what happens if a particular chemical does get in, they reach for sodium lauryl sulfate.

The damaging effect of sodium lauryl sulfate on the skin is objectively measurable - scientists don't ask, "Is your skin itching after shower?" They measure TEWL (trans epidermal water loss) to see how much water the skin is letting out. They also test for erythema, which means skin redness, by measuring the light that is absorbed and reflected. The final common measure is stratum corneum hydration, which measures the hydration of the stratum corneum (a skin layer) by electrical conduction. One study (J Am Acad Dermatol. 1994 Jun;30(6):944-9) showed that the damage caused by sls took 17 days to heal!