Around 60% of the human body is made up of water [1], and everyone knows water is essential to life. Not drinking enough fluids can cause a wide range of health symptoms, but can dehydration cause hair loss?
Well-known brands sell a huge range of products focused on adding moisture to tresses and preventing hair loss. While dehydration isn’t usually the main cause of hair loss or dehydrated hair, it can be a contributing factor. In this article, we’ll explore:
In simple terms, dehydration occurs when the body loses more water than it takes in. This causes a fluid imbalance, which affects normal body processes, such as kidney and brain function [2].
Dehydration can be caused by not drinking enough fluids or by excessive water loss through sweating, urination, vomiting, or diarrhoea. You’re more likely to get dehydrated during very hot weather or during intense exercise.
People taking certain medications, such as diuretics or laxatives, are more likely to become dehydrated. Some medical conditions can also put you at a higher risk, including diabetes [3].
Common symptoms of dehydration include a dry mouth, lightheadedness, headache, and fatigue. If dehydration becomes more severe, you may develop a higher heart rate, low blood pressure, and you might become confused [4].
At present, there is no research specifically on hair loss and dehydration. However, research on surrounding topics gives us some clues that dehydration may cause hair loss.
Research shows your body releases more of a hormone called vasopressin when you’re dehydrated. Increased vasopressin triggers harmful oxidative stress, damaging cells and tissues [5].
Oxidative stress has been identified as playing a key role in the ageing process of hair [6]. Oxidative stress increases in the body as we get older, damaging hair follicle cells, which causes hair greying, slower hair growth, and hair loss [6].
In vitro research does not always translate to real-life findings, and the studies had small sample sizes. However, if dehydration increases oxidative stress, and oxidative stress can cause some types of alopecia, that suggests that dehydration may indirectly be linked to hair loss. If you have hair loss, there’s likely to be another main cause.
While there are no specific studies on dehydration and hair loss, water is important for healthy hair. Drinking enough water improves blood circulation in your body [10], which helps with transporting nutrients to hair follicles.
When you’re dehydrated, you may have limited blood vessel function and higher blood pressure [10]. This can have a negative impact on your heart health by increasing nerve activity and reducing blood flow [10], limiting your supply of nutrients to hair follicles.
Water content plays an important role in the appearance and general health of your hair [11]. Water makes up around 15% of human hair [12], so drinking enough water to keep this topped up is essential. It’s also best to steer clear of chemical treatments, which can damage your hair fibres and reduce their water content [13].
How much water you drink affects skin health, including the skin on your scalp. 64% of your skin [14] is made up of water, which helps it to act as a protective barrier against infections.
Drinking plenty of water can improve skin health and elasticity [15], and you’re less likely to experience flare-ups of conditions like seborrheic dermatitis when your skin is well-hydrated [16]. As conditions like seborrheic dermatitis can cause hair loss [17], staying hydrated can indirectly protect you against hair loss by reducing your risk of flare-ups.
Dehydration is not the most common cause of hair loss. If you’re looking for the reason your hair is falling out, one of these other conditions may be behind it.
Androgenetic alopecia, known as male or female pattern baldness, is the most common cause of hair loss. It affects up to 50% of women and 80% of men at some point in their life [18].
Men often experience temple hair loss and a receding hairline, progressing to a bald spot on the crown, loss of hair on top of the head and, in some cases, complete baldness. Women are more likely to experience diffuse thinning.
Autoimmune conditions like alopecia areata, lupus, and Hashimoto’s disease can cause hair loss. In these conditions, white blood cells attack hair follicles, damaging them and leading to hair shedding.
Stress and anxiety can contribute to hair loss by worsening androgenetic alopecia or triggering telogen effluvium [19]. Telogen effluvium causes hair to temporarily enter the resting (telogen) phase of the hair growth cycle, causing shedding. The diagram below shows the different phases of the hair growth cycle.
Menopause, pregnancy, thyroid disorders and other hormonal imbalances can lead to hair loss [20]. Hormonal conditions like polycystic ovary syndrome (PCOS) can cause hair loss in some women but excessive hair growth in others [21].
Very tight hairstyles such as braids, cornrows, buns and tight ponytails can cause hair loss. Prolonged tension on hair follicles can damage them, causing a type of hair loss called traction alopecia [22].
Research shows certain mineral and vitamin deficiencies can cause hair loss. Nutrient deficiencies that can cause hair shedding include iron, zinc, selenium, multiple B vitamins and more [23]. Interestingly, excessively high levels of vitamin A may also cause hair loss [23].
Hair loss from chemotherapy is well-known, but other medications can cause hair loss as well. These include anticoagulants, antithyroid drugs, lithium, antidepressants, gout medication, and more [24].
There are many other factors that can cause hair loss. These include radiation therapy, infections like scalp folliculitis, seborrheic dermatitis, and others. Learn more about different types of hair loss in the article below.
Your hair can become dehydrated — meaning that it doesn’t receive or retain enough moisture — and systemic dehydration can be a factor in some cases [25]. When it lacks moisture, your hair may be dry, frizzy and dull.
Very dry hair may be more prone to breakage, leading to split ends and even hair loss. Here are some of the most common causes of dry hair.
Excessive heat can dry out your strands [26], including heat from straighteners, curling irons, or holding a hairdryer too close to your hair. Dyeing or chemically treating your hair can also cause dryness, as can harsher types of shampoo [27].
Environmental factors can also affect how dry your hair is. In general, sunlight is not good for your hair — excessive sun exposure can cause dry hair [28], which breaks off easily and feels rough or coarse. Other environmental factors, such as chlorine found in swimming pools, can also dry out your hair [29].
Some medical conditions can affect your hair’s ability to retain moisture. Eating disorders like anorexia nervosa can cause malnutrition, leading to dry, brittle hair [30] and hair loss, among other symptoms. Other medical conditions, such as thyroid disorders, can also cause dry hair, brittleness, and thyroid hair loss [31].
Drinking enough water is important for so many aspects of your health, including your hair. Most people should drink 6-8 cups or glasses of water every day [32] — if you struggle with this, here are some tips to stay hydrated.
Struggling with hair loss? Our expert trichologists can help. Dehydration is not the most likely cause, and these hair doctors can identify the reason your hair is falling out.
Using diagnostic trichology tests like hair loss blood tests or a hair pull test, they can diagnose your symptoms and create a personalised treatment plan. Depending on the cause of your hair shedding, you may be a candidate for a natural-looking hair transplant.
A hair transplant is permanent and can give you thick, healthy hair for years to come. Book a free consultation to get started.
Minimising heat styling, using a conditioner or shampoo for dry hair, and protecting your hair from sun and harsh chemicals can help prevent dryness. If your hair is dry because of an underlying medical condition, it will likely not improve until the condition resolves or is addressed.
Dehydration may cause a dry scalp or disrupt the flow of nutrients to your hair follicles. If you have hair loss linked to dehydration, your scalp may appear dry and flaky. Dehydrated hair will appear dry, dull, and more prone to breakage.
Drinking more water may help with hair loss if it’s linked to dehydration in the first place. Also, if you have conditions like seborrheic dermatitis that cause hair loss, you’re more likely to experience flares when dehydrated — so staying well-hydrated can help to prevent this.
Fixing dehydrated hair may take anything from a few weeks to a few months, depending on the extent of dehydration and the changes you make. Drinking plenty of water, using hydrating hair products, and avoiding heat styling and chemical treatments can help to speed up the process.
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