Hot Water for Itches

We have been writing for many years about a simple remedy that works extremely well. At first, we knew merely that heat could relieve itching. We had no idea why hot water stops itch instantly. Over the last fifteen or twenty years, however, science has provided an explanation on how hot water for itches works.

A Hot Shower for Unexplained Itching:

Q. I’m dealing with intense body itching, especially on my legs. My allergist prescribed hydroxyzine, and that helps somewhat.

The best temporary relief, though, is a hot shower. While somewhat counterintuitive, as health professionals say hot showers dry the skin too much, I find the sensation euphoric for a few seconds. Then the itching subsides for a few hours.

While I’m still seeking an accurate diagnosis of the root cause of the condition, why do hot showers feel so good?

A. Dermatologists have known for decades that uncomfortably hot water can alleviate itching for hours. We found a reference to this remedy in the textbook, Dermatology: Diagnosis and Treatment (1961). (You’ll learn a bit more about that below.)

Ultimately, the doctor needs to diagnose unexplained itching so that the underlying problem can be addressed. In the meantime, hot water can offer temporary relief. Below, we’ll explain how. First, though, we offer a few more testimonials from readers.

Hot Water for Itches Due to Mosquito Bites:

Q. Hot water works for itches! I used the hottest water I could stand for a few seconds on my mosquito bites. It gave much more relief than scratching and lasted for hours. Why isn’t this technique common knowledge?

A. We have been writing about hot water (hot enough to hurt but not so hot as to burn) for itchy bug bites for 36 years. We first learned about this remedy from a 1961 edition of a dermatology textbook. Perhaps it is no longer mentioned in medical school, since dermatologists now have potent corticosteroid creams to ease itching.

Hot water can also be helpful in easing the itch from poison oak or poison ivy. It should never be used for hives, however, as it can make them worse.

A Mosquito Magnet’s Story:

Q. I am a mosquito magnet. The only thing that eases the itch is to put my poor bitten legs under hot running water. Tap water is hot enough.
After I have been out feeding the mosquitoes, I just come in and take a hot shower or an appendage bath and don’t have to suffer more.

A. We first discovered this home remedy for itchy bug bites and mild poison ivy in a dermatology textbook from 1961 (Dermatology: Diagnosis and Treatment, by Sulzberger, M. B., et al.). The hot water (hot enough to be uncomfortable but not hot enough to burn) needs to be applied for just a few seconds to short circuit the nerves that cause itching. The effects can last for a few hours.

We have been using this simple technique ever since we wrote it up in the first edition of The People’s Pharmacy®, back in 1976.

Moderate itching (the sort of thing you get from a mosquito bite or mild case of poison ivy without blisters) often responds to a hot water application. The water needs to be hot enough to be slightly uncomfortable but not so hot that it burns (120-130 degrees Fahrenheit).

If you let the hot water tap run for a few minutes this should be about right. A few seconds’ exposure is all you need to produce several hours of relief.

Hot Water Eases Poison Ivy Itching:

Q. I had poison ivy all over my leg and nothing I tried for it seemed to help much. It may sound crazy, but I noticed that when I got in a hot shower, the hot water felt good on the rash, kind of like I was scratching it.

I found that after putting hot water on it, the poison ivy didn’t itch for a while. So I turned up the heat as hot as I could stand it and held it there as long as I could stand. When I got out, it didn’t itch anymore.

A. Hot water (hot enough to be uncomfortable but not so hot as to burn) can ease itching for hours. It works for poison ivy and insect bites, but not hives.

Another reader shared this experience:

“Your hot water remedy for mosquito bites was amazing! I tried all sorts of anti-itch creams, and none worked as well as a wet towel, 30 seconds in the microwave, and a minute on the bites. I wish I knew about this a long time ago.”

We also heard about a different surprising remedy for poison ivy itching:

“I heard about milk of magnesia last week on the radio program, just as I was having a bad breakout of poison ivy on my legs. As I am very allergic to poison ivy and calamine lotion doesn’t work very well, I was curious to give it a try. Result, it relieved the itching and quickly dried up the oozing sections.”

Hot Water for Itches Is Like Magic:

Many people resort to cortisone cream for bug bites, rashes or other itchy conditions. While it can help, we prefer our favorite home remedy.

Hot water is as close as the kitchen sink. It is surprisingly effective against almost any itch. (The exception is hives; hot water may make that problem worse.)

We first learned about this amazing remedy from a 1961 dermatology textbook. The author recommended very brief exposure to hot water (120 to 130 degrees F). It only takes a second or two to overwhelm the itch sensation from the upper layer of the skin. You can run water over the itchy area straight out of the tap or use a washcloth to cover a place that is hard to reach. The relief may last for a couple of hours.

Why Hot Water Helps:

Doctors did not understand the mechanism for this approach until fairly recently, though. Now we know that transient receptor potential (TRP) channels are essential in the perception of itch (Allergology International, Jan. 2017).  These same channels found on nerve cells are crucial for sensing temperature. Overwhelming those nerve cells with heat can interfere with their ability to transmit itch for quite some time. You do need to be careful not to use water so hot it will harm your skin.

How Hot Water Stops Itch:

How does hot water work? Nobody knew it back in the 1960s, but nerves have specialized receptor channels to detect heat and cold (Temperature, April 29, 2019). These transient receptor potential (TRP) channels play a role in many functions within the body. They also respond to a number of chemicals, such as capsaicin, the hot stuff in hot peppers (Nature, Oct. 23, 1997). We suspect that  TRPV1 is key in this case (International Journal of Molecular Sciences, June 23, 2020). Other research confirmed that TRP channels moderate itch (Neuroscience Bulletin, Feb. 2018).

Even though the dermatologists of yore didn’t know the names of these receptors, they suspected that hot water could short-circuit the neuronal itch reflex. Heat overloads the nerve network so effectively that the urge to scratch is abolished for hours. Relief usually comes within seconds.

Here is what some of our readers have to say about hot water for itches:

“Oh my gosh, hot water on a severe itch brings marvelous relief for a few seconds and then the itch stays away for hours. It’s an addicting feeling. I have a rash right now, and I am actually looking forward to when it starts to itch again so I can use the hot water trick. It’s kind of embarrassing how good it feels, almost like you should be somewhere very private when you do it.”

Another reader harkens back several decades:

“I learned about the hot water method from my mom, a practical nurse, back in the 1970s. She said the hospital where she worked was experimenting with this method to treat patients with severe itching. I have used the hot water method successfully for flea, mosquito and poison ivy itch.”

Finally, a third reader has a complex regimen:

“When I get a mosquito bite, the intense itching lasts for several days. Prescription cortisone creams or oral antihistamines don’t seem to help.

“I use a combination strategy. Hot water is my first choice because it is fast and effective. The water has to be almost hot enough to hurt, but not to the point that it could burn. The Bite Helper [a device that generates heat to apply to a spot on the skin] is useful, but I go through lots of batteries fast!

“Finally, if these first two options aren’t convenient, I use a one-two punch with topical creams. I first apply Biofreeze gel, which has 4% menthol. After a minute or two, as I feel it start to cool and tingle at the bite site, I then apply Benadryl camphor gel with 0.45% camphor. That provides instant relief from even the most intense itch, due to the cooling sensation of the two gels.”

Menthol activates the TRPM8 channel (Journal of Investigative Dermatology, June 2018) and calms itch. (By the way, readers report that Vicks VapoRub, with its menthol and camphor, calms the itch of mosquito bites.)

Many people have reported that camphor is helpful. Like menthol, camphor also activates TRPM8 (Chemical Senses, Sep. 2013). Consequently, we’re not surprised this formula would work. Sometimes it takes decades to find out why an old-fashioned remedy actually works. Now you know how hot water stops itch!

Hot Water for Itches May Also Ease Pain:

Q. Let me add to a recent article describing the benefits of applying a hot water compress to subdue severe itching. I suffer with terrible and prolonged itching from fire ant bites (usually bitten when fishing in the South).

Several years ago, while suffering dreadfully from the itching of about 30 concentrated fire ant bites, I jumped into the shower, adjusted the water to as hot as I could stand, and using my hand-held pulsating shower head, ran it up and down the affected area on my leg. Amazingly, the itching stopped and I never had to chance the consequences of possible infection and scarring that might result from unabated scratching.

I believe that this method of relieving severe itching may be even better than the hot compress application. Not only does the hot water alleviate the itching, but the pulsating water also safely satisfies the urge to scratch.

A. Brief exposure to hot water (a few seconds) can ease itching from bug bites or mild poison ivy. The hot water interrupts the itch signal from nerve endings for a few hours. Do not use hot water for hives, however, as it could make matters worse.

Another reader agrees with this approach:

“Why haven’t you written about an effective remedy for alleviating the agony of poison ivy, mosquito or fire ant bites? Simply run water, as warm as you can stand, over the affected area for a few seconds. The itching and torment is wonderfully relieved for many hours, even overnight. This treatment can be repeated as necessary.

“Several weeks ago, I got nine fire ant bites on my foot. Applying warm water within ten minutes completely eliminated the symptoms. Of course, care should be taken to avoid scalding.”

In his dermatology textbook (Dermatology: Diagnosis and Treatment) from 1961, Dr. M. B. Sulzberger wrote that the water should be quite hot (about 120 degrees F). If it is not hot enough, warm water could aggravate itching. A few seconds under hot running water or a hot washcloth can stop itching for several hours. To be sure, anyone using this technique must take care not to burn the skin.