Why does running make me itch?
Perhaps you’ve had a long shift at the desk, a head-spinning outing with the kids or an extended break from running all together, and now you’re itching to go for a run – metaphorically speaking, of course. But what if you went for a run and developed a literal, physical itch in the process? If this happens, you could be experiencing runner’s itch.
What is runner’s itch?
Runner’s itch – as the term suggests – is an itching sensation that you start to feel during a run, often in the legs and stomach. While runner’s itch usually isn’t harmful or something to be concerned about, this strange side-effect of running can be uncomfortable and annoying to those who suffer the ongoing urges to stop and scratch.
There are various reasons why runner’s itch occurs, and it can especially hinder newer runners or those who are getting back into a running routine. But, thankfully, there are ways to prevent and alleviate it, too.
Here’s what you need to know about runner’s itch, with advice on how to soothe it.
What causes runner’s itch?
The causes of runner’s itch can range from minor inconveniences to more serious health conditions. Although more research is needed to fully understand what triggers this sensation, here are five potential causes.
1. Dry or irritated skin
Both humidity and dryness in the air can lead to runner’s itch.
'If you sweat a lot or if it’s very humid or raining, and your clothes get wet, you run the risk of skin irritation or itchiness,' says Melissa Kendter, C.P.T., a United Endurance Sports Coaching Academy (UESCA) running coach based in Philadelphia.
Braden Romer, Ph.D., an associate professor of exercise science at High Point University in High Point, North Carolina, also points out that hydration is a key factor. 'If you’re not drinking enough water, your skin gets dry and itchy.'
Dry air and dry skin can also commonly cause runner's itch, as the friction generated from running can exacerbate the desire to scratch your skin. In fact, running can aggravate eczema, a group of inflammatory skin conditions that lead to parched skin and itchiness.
'If you’re prone to eczema, exercise might make it worse,' says Minneapolis-based William Roberts, M.D., chief medical officer of the American College of Sports Medicine. 'If you notice a skin rash, talk to your doctor.'
2. Histamine release
When we run – or do any aerobic or endurance exercise – our bodies can generate a localised anaphylactic reaction within the exercised muscle tissues, which causes a histamine release. This was shown by a 2017 study in Exercise and Sport Sciences Reviews, and is believed by Romer to be another cause of runner's itch.
'There’s some research to suggest that the itching may be related to histamine release at the onset of exercise, particularly in higher intensity exercise,' explains Romer. 'If somebody hasn’t been exercising or running for a while, or they haven’t warmed up and jump right into a higher intensity workout, that may trigger a greater histamine release from within the muscle cells.'
This histamine release could then cause that unpleasant itchy feeling when you run.
3. Increased blood flow
When you run, blood flow increases to your tissues, which causes vasodilation – the widening of blood vessels. When your capillaries (your body's smallest blood vessels) widen in this way, it is thought you become more susceptible to the tingling sensation of runner's itch.
'The capillaries start to expand, which may send a triggering response to some of the nerve fibres around that area,' says Romer.
'This can typically happen for newer runners or those getting back into the routine of running, because their bodies aren’t adept at this process,' continues Kendter. 'If your fitness routine has been put on the back burner for some time, you have a higher risk.'
That said, other experts including Roberts doubt that vasodilation could cause itching, and even Romer adds that runner’s itch is not well enough understood to be confidently linked to blood flow. So, more research is needed to fully understand the mechanisms behind this process.
4. Exercise-induced urticaria
In more rare cases, allergic responses to exercise can cause severe symptoms. Exercise-induced urticaria is a rare clinical condition that – as found in a 2022 single case study in Cureus – can cause flushing, itchiness and hives after a workout. A minority of patients can even develop anaphylaxis, which is a severe, life-threatening allergic reaction.
'Exercise-induced anaphylaxis can cause a fast heart rate and potentially the swelling of the throat and blocking of the airways,' says Roberts.
About 30 to 50 percent of exercise-induced anaphylaxis is food dependent, meaning it only occurs with the combination of a specific food and exercise, as shown by another 2017 single case study in Canadian Family Physician.
Many different foods can trigger this reaction, including wheat, shellfish, nuts, tomatoes, peanuts, fish, pork, beef, mushrooms, hazelnuts, eggs, peaches, apples, milk and alcohol.
If you think you’re experiencing urticaria, speak to your doctor. If you know that you suffer from allergies, it’s best to run with another person who knows how to help if you have a reaction. People with severe cases of exercise-induced urticaria may need to avoid certain types of exercise and foods – or, on rare occasions, exercise altogether.
5. Cholinergic Urticaria
Another condition that could cause runner’s itch is cholinergic urticaria, which is again characterised by itching or a stinging pain, redness and bumps.
Think of this as a heat-triggered reaction. Symptoms develop after an increased body temperature has been stimulated repeatedly, such as through exercise, as per a 2023 review in the American Journal of Clinical Dermatology.
'This is also pretty rare,' says Roberts. 'It’s a response to the skin warming that occurs with running.'
Cholinergic urticaria is often associated with serious symptoms like anaphylaxis and severe pain. This condition comes on very quickly and may also involve an antihistamine treatment plan, so speak to your doctor if you have concerns. To confirm whether you’re experiencing cholinergic urticaria, they may conduct testing which could involve raising your body temperature through exercise on a treadmill or stationary bike.
Who is prone to runner’s itch?
Runners who are just starting out, or who haven’t exercised in a while, are more likely to experience everyday runner's itch that isn't related to a more serious medical condition like exercise-induced urticaria or cholinergic urticaria.
'I’ve seen this with athletes who have taken time off,' says Romer. 'My wife also struggles with runner’s itch quite a bit. If she takes some time off from higher intensity runs, especially in the winter, it really gets her for the first few workouts.'
Factors like your age, the dryness of your skin, your hydration levels, your genetics and the climate – particularly desert-like climates with low humidity, or cold climates with heavy wind – can also influence your susceptibility to runner's itch, as well as health conditions like eczema or diabetes.
How can you get rid of runner’s itch?
For many people, runner’s itch will fade away with regular exercise, unless it’s a symptom of a more serious health condition. 'It generally subsides relatively quickly after several workout sessions or by modifying your hydration intake,' says Romer.
Although the first few weeks of running may feel uncomfortable, if you stay consistent and allow your body to adapt to your routine, you’re less likely to experience the itch.
You can also avoid and eliminate runner’s itch by properly easing into your runs. 'Do a good warm up so your body can gradually increase in temperature and the blood can get flowing to the muscles in advance, rather than at a rapid rate during the run itself,' says Kendter.
Staying properly hydrated and using a moisturiser to soothe dry skin can also help. That said, seek medical help if runner’s itch continues for you or if symptoms are severe – for example, if it’s extremely painful, accompanied by a rash or hives, or worsens over time.
'If it becomes a chronic response, where you’re not seeing a diminished response even if you’ve been able to regularly exercise, see a doctor,' says Romer.
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