Methylisothiazolinone (MIT) is a cause of allergic contact dermatitis, an inflammatory reaction that can happen on the scalp and skin if you’re allergic.
Around 10 percent of the UK population are thought to be suffering from allergic reactions due to MIT allergy, but it’s a very common ingredient in shampoos and conditioners.
Dr Lee said: “In acute dermatitis, the skin look reds, swollen and often blistered.
“It can feel hot, itchy and burning, sometimes the blisters burst and the area may be wet and oozy.
“If dermatitis becomes chronic, there may be recurrent bouts of dry, itchy skin, or soreness.”
Sodium lauryl sulphate
Sodium lauryl sulphate is the stuff which makes your shampoo lather into a foam, but you should always try to find a sulfate-free shampoo where possible.
There’s lots of misinformation about sulfates being carcinogenic – sulfates don’t cause cancer, but they aren’t harmless.
This chemical is typically used as a cleaning agent in household cleaners and detergents as well as shampoos so they get the job done, but they also cause skin irritation and damage hair follicles.
The ingredient is too strong for lots of people and should be avoided if you have sensitive skin or a condition such as eczema, rosacea or contact dermatitis.
Sulfate shampoo can cause redness, skin rashes, inflammation, itchiness or hives in people who are sensitive to it.