Seasonal Hair Loss: Real or Myth?

Your dog or cat might lose some fur when the weather heats up, but do humans shed hair in the summer? Is seasonal hair loss a real thing?

In short, yes. You might experience seasonal hair loss at certain times of the year. Seasonal changes or habits (like getting less vitamin D in the winter) can affect the hair growth cycle, possibly causing some strands to fall out prematurely. 

Let’s take a look at the research on seasonal hair loss and other reasons why you might be experiencing hair loss.

Seasonal hair shedding refers to losing hair at different times of the year.

Animals like dogs, cats, and cattle naturally shed their fur in the summer to stay cool and grow thicker coats in the winter for warmth. 

Humans don’t follow a strict annual hair-shedding schedule. But certain seasonal factors may still impact your hair growth, including:

• Shifts in temperature

• Changes in humidity 

• Less sunlight during winter

• Seasonal stress (like the holidays)

• Diet changes 

Of course, how much these affect you depends on where you live. Someone in sunny Southern California will notice fewer seasonal changes than someone dealing with Minnesota winters.

To understand seasonal hair shedding, you need to first understand the hair growth cycle.

The Hair Growth Cycle

Depending on which experts you ask, hair grows in three or four phases:

• The anagen phase (growth phase), which can last years  

• The catagen phase, where the follicle transitions to the telogen phase

• The telogen phase, also called the resting phase, when it stops growing 

• The exogen phase, when hair falls out

After the exogen phase, a new hair will start growing out of the follicle, and the growth cycle begins again.

Every single strand of hair is in a slightly different part of this cycle at any given time, which is why you don’t go entirely bald once every few years. 

What Triggers Seasonal Hair Loss?

Every so often, environmental conditions (among other factors) might shift more hair follicles into the resting and shedding phase. This is called telogen effluvium, a temporary type of hair loss caused by a shock to the system.

Though telogen effluvium is usually caused by issues like illness, severe stress, or significant blood loss, it could also be due to changing seasons. Or even seasonal stress. Think: back-to-school, fall flu, or holiday exhaustion.

When Does Hair Shed the Most?

Before we dig into studies, we want to be clear that there’s limited research on seasonal hair loss. And any that does exist is pretty old. 

So, is there a hair loss season in humans? It’s hard to say. Some people may lose hair during warmer times of the year, while others find that the cold triggers excessive hair loss.

Seasonal hair loss is a difficult idea to pin down, though several studies have tried. For instance, one 2009 study looked at hair loss in more than 800 otherwise healthy women and found that:

• Hair growth and loss patterns have seasonal behaviors

• More hairs are in the resting phase of the growth cycle during the summer

• Spring also sees a higher number of resting hair follicles

• The fewest follicles are in the resting phase during the winter

In an even older study from 1991, researchers found evidence that human hair growth might undergo yearly fluctuations.

They tracked hair growth in 14 healthy males for 28 days and found that the proportion of follicles in the anagen (active growth) phase reached a single peak of over 90 percent in March, and fell steadily until September. The number of shed hairs reached a peak around August or September.

Beard growth was lowest in January and February and increased steadily from March to July. Thigh hair growth showed a similar pattern.

Here’s the thing about this second study: It’s tough to come to any firm conclusions with such a small sample size. 

Does Hair Shed More in Summer?

Hair shedding and hair loss are different but similar concepts. Hair loss refers to a decreasing number of hairs on your scalp, whereas shedding refers to hairs falling out of your scalp, which you might find on your hairbrush or pillow. It’s normal to shed about 50–100 hairs per day even if you’re not experiencing hair loss. Losing more than this may be referred to as excessive shedding.

Our furry friends like cats and dogs tend to shed hair in summer and grow more in winter. But is there a shedding season for humans?

It’s hard to say. Some people may lose hair during warmer times of the year, while others find that the cold triggers excessive hair loss. Many people don’t notice a difference at all throughout the year.

Noticing more hair shedding at certain times of the year? It might not be the season to blame. Factors like genetics or underlying medical conditions could be causing what looks like seasonal hair loss. 

Some of the most common causes of hair loss include:

• Male pattern baldness. Male pattern baldness, or male pattern hair loss, is a genetic form of hair loss that usually starts with a receding hairline around your temples before it progresses to hair loss on your crown.

• Alopecia areata. Alopecia areata is an autoimmune condition that causes patchy hair loss on your scalp, beard, or other parts of your body.

• Traction alopecia. Traction alopecia is hair loss that happens when tight hairstyles or hair accessories pull on hair and damage follicles over time. 

Alopecia Areata and Seasonal Hair Loss

Alopecia areata often causes patchy hair loss that flares up and subsides. Interestingly, flare-ups seem to follow a seasonal pattern.

A 2023 study of 123 children with alopecia areata found that hair loss episodes were most common in the winter (28.1 percent) and least common in summer (21.7 percent).

Why the winter spike? It could be due to lower sunlight exposure — and vitamin D deficiency. Studies show vitamin D deficiency is a risk factor for alopecia areata flare-ups and supplementation might help. 

The American Academy of Dermatology also points to cold temperatures as a potential trigger for this type of hair loss.

Additionally, a 2018 paper published in the Journal of the American Academy of Dermatology looked at seasonal patterns in flare-ups of alopecia areata in over 300 children. It found that flare-ups most often coincided with colder months and happened less frequently in warmer seasons.

The researchers pointed to many unanswered questions about what triggers flare-ups. Also, the study was retrospective, meaning participants reported previous hair loss they experienced. So follow-ups would be needed to see if there was a causal relationship between seasonal changes and shedding — or if it was simply a coincidence.

Learn more about the connection between vitamin D and hair loss. 

Here’s the thing about telogen effluvium: It typically resolves itself. But there are still ways to speed up the regrowth process while promoting healthy hair growth.

When caused by bodily trauma like surgery, chronic stress, or severe illness, telogen effluvium usually sets in two to three months after the event and lasts roughly six months. 

If you have traction alopecia, you may experience hair regrowth once you stop whatever is causing pulling on your hair follicles. 

Hair loss from other causes won’t stop without treatment. Here are a few effective ways to tackle hair loss:

• Try minoxidil. This over-the-counter hair loss treatment can be applied directly to your scalp. It increases blood flow to the area and stimulates hair follicles to enter the anagen phase. You can get minoxidil foam or minoxidil liquid solution online from Hims. It’s an effective, FDA-approved treatment for male pattern baldness. 

• Eat a balanced diet. Nutrient deficiencies can lead to hair loss because your body needs enough nutrients to grow healthy hair cells. So make sure you get plenty of vitamins, minerals, and protein through whole foods.

• Consider hair-growth supplements. Sometimes the simplest way to improve hair care is to watch your diet. If you have a nutrient deficiency you can’t correct with food alone, try a supplement containing nutrients like biotin and vitamin D.

• Be gentle on your hair. Avoid extremely tight hairstyles, constant heat styling, and brushing your hair too often — these can cause breakage and strain your hair follicles, potentially leading to traction alopecia.

• Keep your hair clean. Volumizing shampoo and conditioner might help your hair look and feel thicker. If you’re dealing with flakes, consider our dandruff detox shampoo.

• Corticosteroids. A dermatologist may prescribe you corticosteroids for severe alopecia areata. 

It’s important to talk to a healthcare professional about your hair loss — getting an accurate diagnosis is the first step in taking charge of your hair health.

If you have some hair fall or thinning hair in the summer, it may very well just be due to natural seasonal changes rather than a significant problem or disorder. But only a healthcare professional like a dermatologist can determine the why behind your hair loss.

Here’s what to remember:

• Seasonal hair shedding doesn’t always happen in the summer. Though you might shed more hair in the warmer months, cold weather could trigger hair loss conditions like alopecia areata.

• Treatments are available. Hair loss treatments like topical minoxidil can potentially stimulate hair regrowth. You can also support healthy hair growth by eating a balanced diet and taking supplements.

• Consulting a professional should be your first step. Nothing beats expert medical advice. A healthcare provider can diagnose the cause of your hair loss and suggest treatments.

Seasonal shedding may be nothing to worry about, but it’s still best to talk to a healthcare professional if you have concerns. After all, letting time pass is the worst thing you can do if you’re fighting androgenic alopecia (AKA male pattern baldness).

If you’re seeing signs of hair thinning, we suggest a better-safe-than-sorry approach to treatment. With conditions like alopecia areata, androgenic alopecia, and other types of potentially permanent hair loss, being proactive can mean the difference between saving the hair you have and losing more in the meantime.

We can help you achieve your best head of hair by connecting you with a healthcare provider on our telehealth platform.