The Dermatology Blog

Hives are itchy pink blotches that develop on your skin. They come up quickly, are extremely itchy, then disappear without a trace in minutes to hours. Many things trigger hives including foods, medicines, and sometimes exercise.

Exercise-induced hives (or urticaria) develop when your skin warms during exercise. Once your skin reaches a certain temperature, itchy welts suddenly bloom. The hives favor your stomach, back, or chest but can occur anywhere. One thing is for certain: They always intensify into a maddening itch.

Eating cheese, seafood, celery, or wheat within a few hours of starting exercise can trigger an outbreak. People who have exercise-induced hives also sometimes react when they take medications such as aspirin, ibuprofen, or naproxen before exercising.

In some people, exercise-induced hives occur when they exercise in cold weather. This often happens when they jog in cold weather, ski, or swim in the ocean (especially here in California where the water is always chilly).

If you’re exercising and you develop an itchy red rash, then stop exercising. If the hives don’t go away within 15 minutes, then stop your workout. Avoid eating cheese, celery, seafood, or wheat  for 4 hours before your workout. Similarly, avoid aspirin or ibuprophen for 4 to 6 hours before exercising. Taking antihistamines such as Benedryl or Zyrtec an hour before exercising may help block an outbreak. Antihistamines also hasten the resolution if taken immediately when the rash occurs.

In rare cases, exercise-induced hives cause swelling of the throat, difficultly breathing, and even death. If you develop swelling of your mouth or throat, or difficulty breathing or swallowing, then seek immediate medical help. Patients with high-risk allergic reactions should carry an epi-pen at all times and should never exercise alone.

Photo: Ernst Moeksis

There are some lucky people who don’t get poison ivy or oak. If you’re like me, you do. Here are some poison plant pointers:

Ivy block cream prevents poison ivy or oak, but only if it is applied 15 minutes before exposure. It doesn’t work after you’ve been exposed.

The intensely itchy, sometimes frighteningly-bubbly rash is an allergic reaction to oil, urishiol, found on poison ivy, oak and sumac plants.

You can wash off the oil with soap and water. Do not use laundry detergent, alcohol, or expensive poison ivy soap — any ordinary bar of soap will wash off the oil. However, the oil is quickly absorbed into your skin, like olive oil into nice piece of Italian bread, so time is of the essence. Once the oil is absorbed in your skin, you cannot get it out no matter what you use.

• You can wash off 50% of the oil within 10 minutes
• You can wash off 10% of the oil within in 30 minutes
• After 1 hour, no amount of washing will make any difference. Nothing will prevent the soon to be rash.

Whatever you do, don’t touch your groin in the first hour or so. You could end up in the hospital; I’ve seen it.

After one hour, you cannot spread poison ivy to someone else. Scratching or breaking the water blisters does not spread the poison ivy or the rash.

The rash lasts for 2 weeks, sometimes less if it is not severe. No cream or treatment, however expensive, can shorten the duration. The rash must run its course.

Once your arms and face turn into wet tapioca pudding, use a drying astringent like Domboro soaks to dry it out.

Once the blistering dries up, apply a topical steroid like hydrocortisone 1% cream or anti-itching lotions like topical Calamine or Benadryl. Cool baths with collodial oatmeal will also help. Super hot showers will relieve the itching, but only temporarily, and in the end, only makes it worse.

If you have a severe case of poison ivy, defined by your mother doesn’t recognize you or you are unable to sit, stand, or lie down, then see a dermatologist for prescription drugs to help.

Photo: Jim Frazier (flickr)

Post by Dr. Benabio, copyright The Derm Blog 2009.

Eczema or atopic dermatitis is a common skin disorder seen mostly in children. It is characterized by a red, scaly, itchy rash that can occur on the face, neck, arms, legs, and sometimes the trunk.

We have known for some time now that eczema, also called atopic dermatitis, is also associated with asthma and allergic rhinitis (hay fever). At least 50% of children with severe eczema also develop asthma. Research from the Washington University School of Medicine might shed light on why these diseases go together.

The research, published in the journal PLoS, found that in mice, eczema-damaged skin produced a substance called thymic stromal lymphopoietin (TSLP). TSLP is a signal to the body that the skin has been damaged. When TSLP circulates through the blood, it elicits a powerful immune response. As such, TSLP is your skin’s way of warning you that its protective barrier has been breached and that backup defenses are needed to keep you protected.

Similar to your skin, your lungs are in direct contact with your environment as well, although we don’t often think of it that way. Like skin, lungs are exposed to the air with all its potential pathogens such as bacteria and viruses. It is not hard to see how an inflammatory disease that affects the skin might also affect the lungs. This is exactly what researchers found — when TSLP from the damaged skin traveled in the bloodstream to the mice’s lungs, it triggered inflammation in the lungs (similar to an asthma attack in humans). The researchers believe that TSLP is the link between eczema and asthma.

Ideally, if a drug was developed that blocked the production of TSLP, this might be a way to prevent people with eczema from developing asthma later in life. It also suggests that minimizing damage to the skin can help limit production of TSLP and improve both eczema and asthma.

Photo: Penreyes (flickr)

Cockroaches tend to get a bad rap. As repulsive an animal as they are to many people, the disease that they inflict on us is minimal compared to other insects like mosquitoes or fleas. In fact, although most dermatology books have whole chapters on insects that cause skin diseases, the infamous cockroach is rarely mentioned. Read more…

Despite its association with passion, love, and vibrancy the color red is not what most people want to see on their faces when they look in the mirror. Redness on your face develops from inflammation and from dilated tiny blood vessels right at the surface of your skin. Sometimes the redness can be sudden, whereas other times it can develop slowly over many years. Here are five things your should know about facial redness and what to do about it. Read more…