Medically reviewed by Jill Johnson, FNP
Written by Our Editorial Team
Last updated 10/20/2022
We’ve all seen photos and videos of big, fluffy dogs and cats suddenly reduced to much smaller versions of themselves after falling into a pool or bathtub.
While it’s hilarious to see this happen harmlessly to an animal, for people, it can be a real cause for concern to see your hair lose much of its perceived thickness and volume -- often with visible spaces in your scalp -- after going for a quick swim in the pool.
Wet hair is generally simple to cut, in part because all that volume is reduced to easy-to-manage tendrils, making it easy for a stylist to cut and contour to your face.
But if you’ve ever gotten out of the shower and noticed your head looks a little less lush than its normal appearance, it’s important to remember that you’re not alone.
Your hair doesn’t actually get thinner when it’s wet. However, because your hairs stick together when they’re soaked with water, it’s common for issues such as male pattern baldness to show up -- or at least become more visible -- when your hair is wet.
This means that although wet, thin-looking hair is usually an annoyance, it can also be a useful tool for determining if you’re starting to develop hair shedding.
Below, we’ve explained why your hair generally looks thinner when it’s wet, as well as how wet hair can make detecting the symptoms of hair loss easier.
We’ve also shared several at-home tests that you can use to check for signs of permanent hair loss, as well as the best evidence-based options for preventing hair loss and promoting healthy hair growth.
Wet hair, simply, is matted down. “Matted down” is the common description for what happens when hair gets wet: the strands clump together, making it feel less voluminous and more compact.
This phenomenon is caused by two things. The first is that your normal bouncy and weightless strands of hair suddenly become significantly heavier when they’re exposed to water, as hair is porous and absorbs water quickly.
The second is that the properties of your hair interact with the water, drawing your hairs toward each other in clumps. These clumps occupy less space than the separated hairs, resulting in a perceived loss of coverage of your scalp.
The result of this process is that you look as if you have less hair than you did before getting in the pool or shower, and those hair follicles are indistinguishable from one another due to being clumped together.
Matted down hair has benefits in certain situations. For example, when your hair is wet, it’s far easier for a stylist to trim and shape your hair without losing track of their cuts in a large, poorly defined mass of dry hair strands.
However, when it comes to hair density, matted down hair can be a bit of a shock. Even if your scalp hair is thick and full of life when it’s dry, it’s far from uncommon for it to look severely thin when it’s soaked with water.
To a certain extent, the “thin” look of wet hair is an illusion that’s created, as we covered above, by the effect of your hair sticking together in large, separated strands.
However, when your hair is wet, it can also serve as a great opportunity to take accurate stock of your follicles and see if there are any changes in your hairline, crown or general level of hair thickness and growth.
When your hair is dry, it’s common for its natural texture to conceal some common signs of hair loss, such as a receding hairline or a bald patch near your crown.
For example, if you have hair that’s naturally curly or frizzy and you normally wear it unstyled, it might naturally settle into a position that hides your hairline.
Because your hair clumps together when it’s wet, it can be significantly easier to see bald spots, diffuse thinning, patchy hair loss and other signs of male pattern baldness that might otherwise be covered up by your normally voluminous coif.
This isn’t to say that thinning is dramatically easier to spot when wet. Yes, you may have easier visual access to bald spots or a receding hairline, but to get the best idea of whether your hair is actually thinning, you need to see it in normal (dry) conditions.
Dry hair, after all, is how you look from day to day, unless you’re a professional swimmer. To get the best understanding of your hair’s condition and stay ahead of sudden hair loss, try to look at your hair when it’s wet and dry, preferably under a variety of different lighting conditions.
This is probably a good time to talk about “real” hair loss, as opposed to the trick that water can play on your eyes.
Your hair can thin for a variety of reasons, from severe stress to traction alopecia, a type of hair loss that can develop when tight hairstyles or strong hold styling products pull too firmly on your hair follicles.
However, the most common form of hair loss is male pattern baldness, or androgenetic alopecia -- a form of permanent hair thinning that happens due to a combination of genetic factors and an androgen hormone referred to as dihydrotestosterone (DHT).
Our guide to DHT and hair loss in men goes into more detail about this process, as well as how it can affect your scalp and hair throughout your life.
As you grow older, it’s common for this thinning of hair to become more obvious, resulting in hair that lacks coverage even when it’s completely dry.
It’s also normal for your hair to become physically thinner, less pigmented and slower to grow as you get older. These factors may contribute to some degree of “thinness” even if you don’t have any signs of male pattern baldness.
For most men, this process occurs gradually. Dermatologists and other specialists in pattern hair loss typically use the Norwood Scale to track hair loss as it becomes more severe with age.
How can you tell if your hair is thinning? There are several ways to check for signs of temporary hair loss or permanent hair thinning, including looking in the mirror, using photos to help you, or using a pull test to assess the severity of your hair shedding.
One of the easiest ways to check for hair loss is to simply look at your hairline, crown and other areas affected by normal hair loss in the mirror. You may notice that your hairline looks ever so slightly higher than it did last year, or that your hair simply appears thinning on top.
Since keeping track of your hair loss solely by eye can be difficult, it usually helps to take photos of yourself, then compare them to see if you’ve shed any hair over the course of six months or a few years.
Make sure to compare photos that are taken in similar lighting conditions, as a downward-facing source of light can often create the appearance of thinning even if you have a full head of hair.
Looking at yourself in the mirror or studying photos can often reveal obvious hair loss. However, hair thinning isn’t just about visuals -- it’s also about that fragility and hair breakage problem that can develop as your hair decreases in diameter as you age.
One self assessment you can do, for example, is to simply look for variations between follicles -- signs that some of your hairs are more coarse than others, or that your hairs simply appear less uniform than before.
There’s also something called the hair pull test, which is as simple as it sounds (and much less painful).
Essentially, a hair pull test is conducted by taking a small handful of hairs (about 50) and gently pulling on them. You’ll want to apply enough pressure to pull on the hairs, but not so much that you experience pain or tug out your hair aggressively.
Some of your hairs will pull away from your scalp naturally, and it’s normal to see approximately 10 percent of the hairs that you pulled detach from your scalp and end up in your hand.
If more than 10 percent of your hairs detach from your scalp during a pull test, it could be a sign that you have a form of hair shedding, such as telogen effluvium.
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Whether you’re certain that you’re starting to lose hair, or simply want to start taking better care of your scalp and hair before the first signs of hair loss present themselves, there are numerous options available to treat thinning hair and promote hair growth.
These include FDA-approved hair loss medications such as finasteride and minoxidil, as well as cosmetic procedures for restoring your hair.
For most men, the most effective way to prevent hair loss from worsening and, in some cases, stimulate new hair growth is to use finasteride and minoxidil.
Finasteride is a prescription medication that works by preventing the conversion of testosterone to DHT. This reduces your DHT levels and stops DHT from miniaturizing your hair follicles and causing hair loss.
Lots of scientific research shows that finasteride can slow down, stop and even reverse pattern hair loss in men.
For example, a study published in the Journal of the American Academy of Dermatology in the late 1990s found that balding men who took finasteride showed a significant increase in overall hair count over the course of two years.
Finasteride is effective, but its results aren’t immediate. You’ll generally need to take finasteride for three to six months before you’ll be able to notice any improvements in your hair’s thickness or significant hair regrowth.
We offer finasteride online, following a consultation with a licensed healthcare provider who will determine if a prescription is appropriate.
Minoxidil is a topical hair loss medication that works by speeding up your hair growth cycle and increasing blood flow to your scalp. It’s available as a liquid solution or topical foam and needs to be applied to your scalp twice a day for optimal results.
Like finasteride, minoxidil is supported by a large volume of scientific evidence, including some studies that show it’s particularly effective when used with finasteride.
For example, one study published in the journal Dermatologic Therapy found that 94.1 percent of men with hereditary hair loss showed improvements after using minoxidil and finasteride for 12 months.
In comparison, 59 percent of the men who used minoxidil by itself and 84.1 percent of the men who only used finasteride also displayed improvements.
When medication on its own isn’t enough, procedures like hair transplant surgery can potentially restore hair to areas of your scalp affected by male pattern baldness, such as your hairline and crown.
This type of procedure can be costly, meaning it’s best considered when you have a significant amount of hair loss that may not fully improve with finasteride and/or minoxidil.
It’s normal for your hair to look slightly thin when it’s wet. This is because the tens of thousands of strands of hair on your head tend to clump together when exposed to moisture, resulting in a larger gap between each group of hairs that reveals more of your scalp.
As such, it’s generally best not to worry too much if you notice that your hair looks thin when it’s wet but normal when it’s dry.
If you think you’re beginning to develop a receding hairline, a bald patch at your crown or more diffuse thinning that affects your entire scalp, it's best to bring your concerns to your healthcare provider.
They’ll be able to let you know if you’re suffering from male pattern baldness, hair shedding or a more serious health issue that’s affecting your scalp and hair follicles.
Interested in getting help for thinning hair right away? We offer a large range of evidence-based hair loss treatments online, including FDA-approved medications for preventing pattern hair loss and stimulating hair growth.
You can also learn more about your options for dealing with noticeable hair loss in our full guide to the best treatments for thinning hair.