Beauty writer's dry shampoo trick means she only washes her hair once a week

The secret comes in using it at the right time of day

(Mood Board/REX Shutterstock)

Dry shampoo, the festival fail safe and friend of the greasy fringe, might languish at the bottom of your handbag for hair emergencies.

But a beauty blogger has cast waves online by revealing how the product enables her to wash her hair only once a week – saving precious time and money.

Hair becomes dirty due to the build-up of sebum: an oil which emanates from the sebaceous glands present everywhere except from the palms and the soles of the feet.

The build-up of sebum in the hair enables dirt to cling to it. Dry shampoo works by absorbing the build-up of oil from your hair.

Beth Wischnia of the Brit+Co website writes that she uses dry shampoo at night because it absorbs oil and adds volume to the hair overnight.

She warns that your hair will look “crazy” when you first wake up, but passing a brush through it will leave you with volume and shape.

To try this method, lift your hair up and spray a generous amount onto the roots.

However, dry shampoo shouldn’t entirely replace washing hair regularly.

According to Dr Wilma Bergfeld, a dermatology specialist at the Cleveland Clinic said: “Dry shampooing has its place, but no wet shampooing has no place,” she says.

"Your hair and scalp needs to be washed and rinsed intermittently to keep it clean.”