Woman with brunette long hair blowing in the wind

Truth or Myth: 17 of the Most Common Hair Myths Debunked

Is there really any truth to these old wives' tales?

Whether it’s brushing your hair 100 times before bed or eating your crusts to make your hair go curly, we’ve all heard the stories. But how much truth is there to these old wives’ tales? To help shed some light, we spoke to Charlotte Rogers, Global R&D Representative at Unilever, to find out which of these popular hair myths are actually backed up by science.

1. Rinsing Your Hair in Cold Water Makes It Shiny

True – Kind of!

When you wash your hair, water causes the hair to swell, causing cuticles to partly lift from the hair surface. Using hot or cold water won’t significantly change this swelling process as your hair will still absorb a lot of water.

However, there is evidence that using hot water could cause more removal of conditioning agents in products when rinsing, so a blast of cold water could help.

2. Swimming Pools Can Turn Blonde Hair Green


Sorry blondies, but this one is true! Contrary to popular belief however, it’s not chlorine that causes this. It’s actually caused by copper in the water binding to protein in your hair, causing a chemical reaction that gives hair that green tinge.


Don’t want to wear a swimming cap? Try putting a leave-in conditioner like the TONI&GUY Leave In Conditioner in your hair before you swim – it’ll act as a barrier while also conditioning your strands.

3. Towel Drying Damages Hair


While it might seem like an innocent motion, rubbing your hair with a towel can influence the structure if you’re pulling and twisting the hair too hard, causing the fibres to weaken and snap.

4. Washing Your Hair With Mayonnaise Makes It Shiny


One of the weirder at-home hair treatments we’ve come across is something you’ve probably never thought of putting on your hair before – mayonnaise. Even Blake Lively has admitted to slathering her hair in the condiment before washing it to tackle dryness.

Mayonnaise is said to contain amino acids that make up the protein in our hair. Amino acids can with help strengthening and is the reason why you might see these added to hair products such as conditioners.

But as far as using mayo straight from the fridge to get these benefits, well, the jury is still out.

5. Hair Can Develop Product Immunity From Using the Same Products for Too Long


Hair isn’t alive. And since our hair isn’t alive it can’t develop immunity. If you’re seeing differences in your hair, this is probably due to other factors like pollution particles, damaging UV rays or simply overusing styling products.

TRESemmé Replenish & Cleanse Shampoo Front View


To avoid this happening, try using a clarifying shampoo like the TRESemmé Cleanse & Replenish Deep Cleansing Shampoo in place of your regular shampoo once a week.

6. Washing Your Hair Every Day Dries It Out


Whether you can’t stand the grease or you simply love an indulgent shower, you’ve probably wondered if washing your hair every day is drying out your strands.

Well, the jury is out and it’s inconclusive. Washing your hair can slowly remove structural components such as protein and lipids which help to keep hair strong and healthy. However, there isn’t much evidence to suggest that washing hair every day compared to a few times a week is enough to make a noticeable difference.

7. If You Pull out 1 Grey Hair, 2 Grow in Its Place


If you lose a hair, only one can be produced in its place from the same follicle. This means one grey hair won’t come back as two and we can all sleep a little easier at night now.

However, this doesn’t mean new grey hairs aren’t growing at the same time (sorry!). We have up to 150,000 follicles on our head, so if you’ve found one odds are there will probably be others.

8. Stress Makes Your Hair Fall Out


Alopecia Areata is one of several hair loss conditions. It can cause sudden loss of clumps of hair in different areas of the scalp. This is mostly due to your genetics but the condition can be triggered by severe stress.

This cause of hair loss is complicated and believed to partly be due to restricted oxygen reaching your follicles, meaning they can’t function and grow hair as normal.

9. Wearing Your Hair Tied Too Tight Causes Baldness


As much as we adore ponytails, updos and braids, they all put stress on your hair. The first signs of change are likely to be breakage and split ends, especially in areas where an elastic is tied.

In very severe cases, where the hair is repeatedly pulled back, you can cause what is called traction alopecia. This is where the hair won’t be able to grow from certain follicles as they are so damaged.

10. Lemon Juice Lightens Hair


Lemon juice itself cannot cause your hair to change colour, it needs the sun. It is the acidity in the lemon juice which helps speed up this process.

However, sitting in the sun with lemon in your hair only works for blondes, who may see some lightening of the hair. If you have darker hair it may only turn slightly red.

The science is that UV rays cause internal reactions with the hair, impacting the pigment. UV can also be damaging (eek) breaking down important proteins within your hair, making it weaker.

So, sorry to the fans of using lemon juice in their hair: we’re calling this one a hair myth.

11. Brushing Your Hair Regularly Makes It Shinier


Period dramas often feature ladies having their hair brushed 100 times before bed because the practice has long been touted as the key to super shiny hair.

However, our hair experts did some investigating and discovered that this one is more of a hair myth than truth. In fact, regular brushing can actually cause more hair breakage, leading to split ends and dullness.

Using a shine spray is a much quicker (and more hair-friendly) way of adding shine to your look. The VO5 Tame & Shine Spray gives locks a shiny and polished finish and also contains heat defence for even more mane-protecting benefits.

12. Leaving Conditioner in Overnight Makes It Work Better


Dry hair? Then you’ll be pleased to hear that this one is true! If you really want soft, smooth and all-around swish-worthy hair that doesn’t feel crisp, leave your conditioner on for more than just your quick shower sesh.

13. Eating Your Crusts Makes Your Hair Go Curly


Did your grandparents ever tell you growing up that eating the crusts on your sandwiches would make your hair go curly? This old wives’ tale has been around for generations but sadly hair type is determined by genetics!

Your hair follicles influence how your hair grows, with straight hair growing from straight follicles, while curly hair grows from bent follicles. Different proteins work in different locations of the different follicle types, leading to the different shapes and unfortunately, eating your crusts won’t affect this!

14. Cutting Is the Only Way to ‘Mend’ Split Ends


The only way of mending split ends is to cut them off. But that’s not to say that there aren’t things that can help minimise the look of split ends. For example, particles in conditioners and leave-on treatments can deposit onto the hair fibre, acting like glue to temporary seal split ends and make your hair look healthier.

Handbag-sized and great for touch-ups, VO5 Split End Rescue Balm helps to reduce the look of split ends and smoothes down flyaways.

15. Getting Your Hair Trimmed Regularly Makes It Grow Faster


We’re always told that getting regular trims is the key to making your hair grow faster but how much truth is there to this? We’re sad to say – not a whole lot.

Hair grows from the follicles, so cutting the ends off won’t affect growth rate. But more importantly, how fast your hair grows is pre-determined by your genes, which work in sequence over a hair’s lifecycle and can’t be sped up with scissors (sorry!).

However, cutting the ends of your hair removes split ends which can make your hair look thinner, so while trims may not make your hair longer, they can make it appear fuller and healthier.

16. You Can Go Grey Overnight


Hair greying is a gradual process. It happens because as we age, pigment cells in our follicles stop producing a chemical called melanin. Every time the hair regenerates, you have to reform these pigment-forming cells and they get tired, eventually wearing out.

17. You Can’t Colour Your Hair During Pregnancy


This one is inconclusive. Generally, it’s thought that the chemicals used in dyes are safe to use when pregnant at the levels you need to change hair colour. However, there’s not enough research on this to say for sure either way.

There are precautions you can take, especially in the early stages of pregnancy, when the risk of chemicals harming a child are greater. If you’re doing it yourself, use gloves, make sure you’re in a well-ventilated room and leave the dye on for the minimum time possible.

There are certain chemical hair treatments however that should definitely be avoided when pregnant, including the chemicals used to relax or permanently straighten hair.



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