Join an NIH study if you suffer from urticaria from water, sun, pressure, vibration or exercise

Several readers contacted me after a previous posting about jogging causing itching.  The below NIH study may be of interest from people who suffer from this condition and also other urticarias.

A team at NIH led by Dr. Hirsh Komarow is studying physical urticarias caused by water, sun, pressure or vibration (such as caused by exercise or exposure to vibrating tools, etc).  Dr. Komarow is recruiting patients for this study and particularly interested in patients with other family members who are affected as well as severe cases.  The link to the study is available on the clinical site here .  If you are interested or are looking for more information, contact: or (301) 594-2197.

I’m looking forward to seeing the results of this study.

When tarantulas attack…


People often come into the clinic worried about spider bites.  While the majority of these concerns turn out not to be spider bites, it does raise the question of what sorts of medical conditions spiders can cause.  In the United States, tarantulas (shown on the left) are one type of spider that may be found in the wild and as pets.  While tarantulas can bite, a more common form of defense is for the tarantula to throw its hairs at a predator (e.g. at you if it thinks you’re going to attack it!)  These hairs have little barbs and are urticating, meaning they can cause urticaria (a fancy word for hives or wheals).

These little barbed hairs can lodge in the skin and cause wheals or, they can also lodge into the eye.  When they lodge in the eye, these tarantula hairs cause a condition called ophthalmia nodosa.  These barbs in the eye cause the eye to get inflamed and could actually lead to vision loss if severe enough.

Needless to say, if you believe you’ve been attacked by a tarantula, you should probably get checked out.  More on other spiders (e.g. black widow, brown recluse, etc.) in future posts.

“Skin writing” – aka dermatographism/dermographism

An example of dermatographism. courtesy of Wikipedia user R1carver

For some people, scratching the skin leads to raised wheals, demonstrating dermatographism which literally means “skin writing.” Scratching or stroking the skin leads to redness and a wheal of that area. About 5% of the population develops redness and some swelling of scratched areas — this is called simple dermatographism. In symptomatic dermatographism, these areas become itchy as well and the wheals are more prominent. In general, wheals develop about 5-10 minutes after the scratching but sometimes they can develop after a longer period of time. Your doctor can test whether you have dermatographism by gently scratching your skin (

usually your back) and seeing whether a wheal forms.

If you have dermatographism, try to avoid stimuli like scratching which lead to the discomfort. Antihistamines can also offer symptomatic relief.

Does jogging make you itch?

courtesy of Flickr user ceiling
Does jogging make you itch? I remember those mile runs in grade school when my thighs would end up with a strange tingly itchy slightly swollen feeling and covered with faint pink blotches. Turns out that this is a condition called vibratory urticaria. It’s caused by mast cells which get stimulated by vibration to release histamine and other contents. In this case the histamine and contents inside of mast cells leads to itching, swelling and redness. While many people report vibratory urticaria happening with jogging, it can also occur when operating machinery such as lawnmowers, jackhammers, etc. I just have a mild case of vibratory urticaria. Some people can develop more intense swelling or a life-threatening condition called anaphylaxis with exercise. Rise in body temperature itself can also cause urticaria (hives) and occlusion of hair follicles after exercise can cause folliculitis. So there are all sorts of skin conditions that can happen with exercise!