Itchy skin is something we’ve all dealt with at some point, but if you notice you often get itchy when working out, you probably want to know, “Why do I get itchy when I work out?” This can be irritating and distracting, but it’s not uncommon. For some people, this itchiness happens during the exercise, while other people feel itchy after a workout. Let’s explore why it can happen and what you can do about it.

Understanding Exercise-Induced Itchiness

There are several reasons for feeling itchy when working out, but one of the most common reasons is the expansion of your arteries and capillaries. This is what causes what’s commonly referred to as “runner’s itch.”

Exercise increases your heart rate and blood pressure, which helps your heart deliver more blood and oxygen to your muscles. To accommodate this increase in blood flow, your arteries and capillaries expand, which can push on the surrounding nerve cells, stimulating them and sending signals to your brain. Your brain interprets these signals and, you guessed it, makes you itch.

While this is the most common cause of itching during exercise, other factors can also contribute, including:

• Allergies
• Exercise-induced histamine reaction
• Skin reactions
• Vasculitis

Common Causes of Itching During Exercise

Does it seem like something else is causing you to feel itchy after a workout? Let’s look at other common causes of exercise-induced itchiness.

Allergies

In many cases, itchy skin can be caused by an allergic reaction to something in your environment, on your skin, or even something you’ve ingested. Consider the following allergic reactions to determine what’s causing you to feel itchy when working out. As with any allergy, if any symptoms of anaphylaxis are present, seek medical help immediately.

Contact dermatitis: This occurs when your skin comes into contact with an irritant, such as athletic clothing, a yoga mat, or a new body product. Start by eliminating anything new your skin is in contact with and reintroduce things one at a time to see if you can pinpoint the problem.

Environmental allergies: Pollen, pet dander, perfumes, or even cleaning products may be causing your skin to itch. Consider whether you’re inhaling or touching something in your environment that could be triggering an allergic reaction. Look for hives, too.

Food allergies: If you have food allergies, you may have come into contact with the allergen while exercising. Some people also experience increased food allergy sensitivity during exercise. If you think this might be the culprit, consider keeping a food diary and talking to your gym about potential exposure to allergens.

Non-Allergy Immune Reactions

In some cases, your body’s immune system may respond unusually to exercise. The following non-allergy immune reactions are typically mild, even if they make you feel itchy when working out. However, as with true allergies, it’s important to look out for signs of anaphylaxis.

Histamine response to exercise: Some people’s bodies release histamines, just as they would when an allergen is present. While not a true allergy, research indicates that the body may release histamine to expand your arteries and capillaries further, but it may also prevent fatigue.

Urticaria: This immune reaction occurs as your body temperature rises during exercise. It behaves like an allergic reaction, though it technically isn’t one. Urticaria causes skin symptoms like hives, itching, and redness, though it can also cause headaches, difficulty breathing, stomach cramps, and swelling of the face, tongue, or hands. Stop exercising if you experience these symptoms, and contact your doctor if they don’t resolve within 10 minutes.

Vasculitis: This rash is caused by inflammation of the blood vessels and is frequently due to a combination of heat and exercise. The inflammation of the blood vessel walls restricts blood flow, and the nerves can respond by sending signals to your brain that create pain, burning, or itching.

Skin Reactions

Sometimes, your skin is the cause of your post-workout itchiness. Whether you already have a skin condition or your workout causes a skin reaction, feeling itchy after a workout can be common.

Atopic dermatitis or eczema: If you have a skin condition that already makes your skin feel itchy and irritated, exercise is likely to exacerbate the problem. The change in body temperature and excess sweat can dry out your skin and irritate it further.

Heat rash: If you get overheated, you might end up with a heat rash as a result of sweat that gets trapped in your pores. Heat rash is more likely to occur after exercising in the heat or under tight athletic clothing.

Sensitive skin: Sensitive skin is already prone to itching, and sweat combined with irritation from workout clothes or laundry products can make it worse. Additionally, if you have dry skin, sweat will further dry it out.

Can Dehydration Cause Itchy Skin?

If you’re still wondering, “Why do I get so itchy when I work out?” it might be because you’re dehydrated. Unfortunately, dry skin tends to be itchy, and when your body is dehydrated, exercising only worsens the issue. Dehydrated skin is different from naturally dry skin, which lacks oil. Dehydration, on the other hand, is the lack of water, and that’s due to losing more water than you’re ingesting. In addition to being itchy, dehydrated skin is dull and uneven, and you may notice fine lines are more pronounced. Proper hydration can solve this, but it requires intentionally focusing on drinking enough fluids. Every time you work out, you’ll need to replenish.

It’s also worth noting that any major change in your diet can disrupt your hydration levels or microbiome, leading to a variety of issues, including itchy skin. Even cutting out sugar causes symptoms of sugar withdrawal, and the results of that can include itchy, rashy skin. Focus on balanced nutrition in addition to hydration to help combat itchy skin.

Preventing and Managing Itchy Skin While Working Out

Whether you take steps to prevent or manage the itch (or both!), there’s a lot you can do to treat itchy skin after exercise.

For itching due to the expansion of arteries and capillaries, the good news is that it’s usually worse when you’ve been away from your workouts for a while. The more consistent you are with a workout routine, the less likely you’ll experience this itching during exercise. As your brain gets used to the signals sent by your nerve cells as your capillary walls expand, it learns not to respond with that annoying itching signal. Until then, you can try warm baths with Epsom salts, calamine or hydrocortisone creams to relieve the itch, or even apply a cold pack to itchy areas.

If you think you might be having an allergic reaction, start by eliminating anything you think might be the culprit, and keep a diary of what you eat, wear, and encounter to see if you can identify the source. It’s also a good idea to talk to your gym to see what allergens you might be exposed to, from pet dander to cleaning products to foods. You can also talk to your doctor about using an antihistamine to help manage your allergy symptoms.

Finally, if you think it’s an issue with your skin, make a few changes. First, try to use gentle products made for sensitive skin and change out sweaty clothes right away to reduce itching. Avoid exercising during the hottest times of the day or in bright sun. Make sure you’re properly hydrated at all times, and replenish lost fluids after every workout. Moisturize your skin after bathing to soothe irritated skin and maintain moisture.

The Bottom Line: Is Itchy Skin Something to Worry About?

If you make all the changes above, work out regularly, and still experience significantly itchy skin during workouts, it’s worth checking in with your doctor. In most cases, it’s unlikely to be anything to be seriously concerned about, but there may be additional tests that can help you resolve the problem. As long as you’re not experiencing signs of anaphylaxis, you’ll most likely be able to resolve the problem relatively easily with a few small changes.