Can you use human shampoo on dogs?

No. It is recommended to avoid using human shampoo on a dog. The pH of a dogs skin varies between 6.0 to 8.0 with an average pH of 7.0 (neutral). Different breeds can have different skin pH levels. Human skin however ranges from 4.8 to 5.8 (acidic). Even human baby shampoo is up to 150 times too acidic for a dog's skin. Keep reading below to find out why this matters 

Protective layers

A dog's skin is a lot more sensitive than ours. We have 10 to 20 layers of skin cells, dogs average 3 to 5 layers. Their skin is much thinner and lacks the protective layer our skin has. Most of a dog's skin is protected by their coat, ours is not. We have an extra, protective layer called the acid mantle, that dogs don't.

Exposure time

Another factor is exposure time. When we shampoo our head, we don't leave the shampoo in contact with our skin as long as we do when we shampoo a dog's entire body. 

pH, itching & knots

Human shampoo is too harsh for a dog's thinner, more sensitive, less protected skin. This can disrupt the natural pH of the dog's skin, stripping the epidermis, and leave their skin open to bacterial infection and inflammation. It can also cause the coat to become dry and flaky, increasing itching and irritation. This reduces protection from flea bites, strips flea protection products, and drying the coat also makes it more prone to knots and mats. 

A small difference in pH is a big change in real terms. The difference between a pH of 5 and a pH of 6, is 100 times more. That means a pH of 5 is 100 times more acidic than a pH of 6. Johnson and Johnson baby shampoo has a pH of 5.5.