Black dog with shampoo
© Pixabay

Can a dog be washed with human shampoo?

By Nick Whittle Author

Updated on the

Picture the scene: you find yourself with a spare evening and plan to devote it to washing your dog. You scour the doggy cupboard for everything you need but realise you have run out of dog shampoo. What do you do? Can you actually wash your dog with human shampoo?

In truth, yes, but only as a last resort. Ideally washing your dog with human shampoo even once a year is too much, and there are two reasons to avoid its use:
1) There are many more chemicals in human shampoo than in dog shampoo 
2) human shampoo is more alkaline than dog shampoo.

There is a third reason for avoiding human shampoo: a dog’s skin is a fraction of the thickness of human skin and is more prone to nasty infections. Human shampoo washes off the dog’s protective layer of oil and leaves her vulnerable to things like skin irritations, infections, psoriasis and wet eczema.

What’s the difference between dog and human shampoo?

Aside from the chemical ingredients (more on this later), human shampoo has an alkaline nature. Something which is alkaline is the opposite of acidic. Human skin is more acidic than canine skin and we use alkaline detergents to clean our bodies because the two together cancel each other out, leaving our skin neutral.

Even for us, cleaning with the wrong product or over cleaning can make our skin poorly. That’s why when people wash too much, especially people who are obsessed with their cleanliness, they find their skin becomes irritated.

Dog shampoo is more neutral to start with so won’t be as abrasive as our soaps. Most good dog shampoos also contain a hypoallergenic formula that prevents too much damage to the natural oils that waterproof the dog’s coat.

Symptoms of washing a dog with human shampoo

Dogs can have negative (and sometimes severe) reactions to human shampoos and other products such as shower gel and soap. But on occasion even some of the cheaper dog shampoos can cause problems.

Clinical signs of a reaction to a product include irritated and inflammed skin, swellings and sores. What's more, ingestion of human shampoo can cause vomiting and anorexia. If you notice these symptoms, re-wash your dog just with warm water and monitor her condition over the next 48 hours.

Often symptoms associated with atopic dermatitis and allergies such as incessant scratching, rubbing and licking can worsen with time if untreated. The most commonly affected areas of a dog include:

  • Wrists
  • Ankles
  • Toes
  • Ears
  • Muzzle
  • Underarms
  • Groin
Symptoms associated with atopic dermatitis can worsen with time if untreated. © Shutterstock

What’s human shampoo got in it?

We add things to our soaps: additives, colourings and perfumes are put in almost every cleaning product, and most of the time they are all artificially made: chemicals are combined to make things either smell nice or look good. In essence, most commercial shampoos are just a concoction of surfactant chemicals (most of which on their own are toxic), distilled water and glycerine.

Let’s have a look at the bad stuff found in human shampoo (and some dog shampoos) that can be toxic to your dog’s skin and her insides.

  • Artificial colour: Mostly petroleum derivatives, artificial colours are made up of so many chemicals that is almost impossible to know exactly what you’re applying to your dog’s body.
  • Artificial fragrances: Again mostly petroleum derivatives are used in the process; including benzene and toluene, which are both carcinogenic.
  • Cocamide: Chemically altered derivative of coconut oil, but has been linked to some cancers in humans.
  • Cocamidopropyl Betaine: As above, but with added toxins which effect the immune system.
  • Isopropyl alcohol: A petroleum derivative that can cause digestive burns if ingested and respiratory irritation; also known to be toxic to the liver and nervous system.
  • Methylchloroisothiazolinone: Known as a carcinogen and toxin, this chemical acts as a preservative.
  • Mineral Oil: Another petroleum derivative that can ‘suffocate’ your dog’s skin.
  • Formaldehyde: A well-known fluid for embalming dead people; this affects the nervous system.
  • Parabens: Added to shampoo as a preservative, parabens are considered liable to disrupt hormone balance. Dogs with elevated oestrogen are more susceptible to some cancers.
  • Polyethylene glycol: Used as a solvent in shampoos, polyethylene glycol is thought to wreak havoc of a dog’s digestive, nervous and immune systems.
  • Sodium laureth sulphate: Known to be a carcinogen, laureth sulphate is part of the detergent mechanism of the shampoo.
The artificial colours of shampoo are made up of petroleum derivatives. © Pixabay

If the above list isn’t reason enough to avoid washing your dog with human shampoo what is? But beware: some commercial dog shampoos contain similar ingredients. Beware of products that claim to be full of natural ingredients too; many of these are still packed with artificial fragrances and colours.

It is hard to find a dog shampoo that does not contain some of the detergents of the human sort; some 'gentle' dog soaps are so gentle that they do not clean the dog as well as we want.

Want to know how your dog’s skin will react to a certain shampoo? Why not patch test it first. Use some water and a small amount of shampoo, mix it into your palm and rub it on one part of the dog’s body, wash it through and leave it for a week to see what reaction (if any) there is.

Once you are confident that you have found the right product for your dog you shouldn’t have to worry about her having an allergic reaction. As always, vigilance is a key component of caring for a dog.

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