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

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.

Now, if you have ever seen a cockroach scamper across the floor and felt yourself develop a rash, you are not crazy. Although they do not often transmit diseases, cockroaches do have potent antigens that can trigger eczema. These antigens are proteins that when they contact human skin trigger an inflammatory response. The antigens from cockroaches are similar to antigens from dust mites (a notorious instigator of allergy). 

When they contact the skin, the antigens activate a receptor in the skin that causes inflammation. The inflammation also causes an itching sensation and inhibits your skin’s ability to heal. 

It is well known that allergens from cockroaches can make asthma worse. Over 1/3 of of people who live in cities and have asthma are allergic to cockroaches. We also knew that some people develop a rash if a cockroach crawls on their skin. (How some people can sit still while a cockroach crawls on their skin is still unknown to science).

Specifically, cockroaches can trigger a skin condition called atopic dermatitis. Atopic dermatitis is another name for eczema — it is an itchy red rash that develops most often in childhood. In most people, eczema improves with age. Atopic dermatitis develops when the skin’s normal protective barrier is disrupted and the body’s immune response is overly aggressive. The rash from atopic dermatitis is often red and scaly and appears mostly on the neck, folds of the arms and legs, and the face. 

A recent study published in the Journal of Investigative Dermatology studied the effect of cockroach allergens on the skin. They found that both cockroach allergens as well as dust mite allergens caused a breakdown in the protective barrier of the skin after just 3 hours of exposure. By breaching your skin’s exterior defences, the allergens can easily trigger an inflammatory response that leads to a red, itchy rash that can last weeks or more. 

To prevent this eczema trigger, I would suggest you avoid cockroaches.

If it is impossible for you to avoid cockroaches (which is the case in many cities), then keeping your skin protected with a good barrier cream is important. Any ointment (such as Vaseline) or a cream that contains silicone such as Eucerin Intensive Repair Body Creme, can provide a good barrier to prevent allergens from entering your skin and block the triggering of eczema.

Can putting bacteria on your skin actually cure disease? Perhaps.

Eczema (which is also called atopic dermatitis) is a common skin condition. People with eczema have itchy, scaly, dry skin. It often develops in infancy and improves as you get older. Some people with severe eczema have the disease for their whole lives. Atopic dermatitis seems to develop in people because they have both an imperfection in their skin’s barrier and because their immune system is a over-active.

A new way of thinking about eczema, as well as many other diseases, is that there is also an imbalance of bacteria living on your skin. Each of us has literally trillions of bacteria living on our skin as well as in our intestines and respiratory tracts. Whereas we traditionally think of infection from bacteria as causing disease, it seems that some diseases might be the result of loosing normal bacteria. This is why many people take probiotics and eat yogurt for gastrointestinal disorders — eating these bacteria-laden foods and supplements replenish normal bacteria — bacteria that is meant to live with us. These species of bacteria that share our bodies are known as normal flora (sounds like were walking flower gardens, doen’t it?).

Now a study from the United Kingdom has found that applying a cream that contains a non-pathogenic bacteria, Vitrescilla filiformis, to patients who have eczema can actually treat their skin condition. The study, published in the British Journal of Dermatology, found that patients treated with cream with a 5% concentration of the bacteria for 30 days had significantly reduced eczema, itching, and sleeplessness (from scratching at night) as compared to patients who applied a placebo cream that did not contain the bacteria.

The authors speculate that using the bacteria laden cream might work because the heavy concentration of “good” bacteria displaces “bad” or pathogenic bacteria such as Staph aureus. It might also be that restoring the normal flora on your skin helps to calm the immune system, decreasing the eczema in these patients. 

In either case, the results of this study are interesting. I think that in the future we will be reading much more about the importance of mantaining a healthy growth of bacteria on your skin. Of course, this does not mean that next time you hurt yourself, you should “rub some dirt on it,” like Peyton Manning recommends. Dirt has lots of not-so-good bacteria in it that is likely to do more harm then good.

Then again, Peyton has a superbowl ring and I don’t, so maybe you should listen to him.

Tea tree oil is an essential oil that has antiseptic properties. It has been used as a natural antifungal and antibacterial agent. You might have heard that teat tree oil can help treat acne because it kills acne-causing bacteria. However, unlike benzoyl peroxide and retin A, there is not much evidence that tea tree oil is an effective treatment for acne.

There are only two published studies on the use  of tea tree oil for acne. The first was done about 10 years ago in Australia. It showed that 5% tea tree oil is comparable to 5% benzoyl peroxide. The tea tree oil took longer to work, but appeared to be less irritating than the benzoyl peroxide. The second study, which was done in Iran, showed that 5% tea tree oil was more effective than a placebo in treating acne. Comparing tea tree oil  to a placebo, which is essentially comparing it to non-treatment, is not the same thing as comparing it to another acne-fighting treatment. It’s likely that tea tree oil has some effect on acne but it has never been shown to be better than traditional acne therapies.

In contrast to other acne treatments, however, tea tree oil is an increasingly common cause of skin allergies. Like other fragrant oils such as balsam of Peru, tea tree oil can trigger an allergic contact dermatitis in people who are sensitive. This can range from a minor itchy rash to a full scale blistering eruption.

Tea tree oil is also toxic if swallowed. If consumed, even in small doses, it can cause reduced immune function, abdominal pain, diarrhea, drowsiness, confusion, or even, in rare instance, coma.  If applied in the ears, it can lead to hearing loss. It has been shown to be toxic to animals when applied to a large area of skin. Tea tree oil can affect hormones as well. One study published in The New England Journal of Medicine showed that repeated application of topical products containing tea tree oil (and lavender oil) could cause prepubertal gynecomastia, a rare condition resulting in enlarged breast tissue in prepubscent boys. Tea tree oil is not recommended for pregnant or nursing mothers.

Because tea tree oil is a naturally occurring substance, it tends to get good publicity, but it’s probably only an average or below average product for acne. Oftentimes people believe that since tea tree oil is natural, it must be safe and better for you than traditonal acne treatements. It’s not true. Remember, turpentine (a related tree oil that is used to strip paint) is also natural, but it doesn’t mean it’s good for you.

Photo: Shek Graham

Yep, they can. In fact, the unfortunate few people who have this problem can actually risk their lives just by taking a shower.

The allergy is a rare condition called aquagenic urticaria. People who have it develop intensely itchy, even painful hives when their skin comes into contact with water. The itchy wheals or hives develop within minutes of exposure and can persist for hours afterward.

Interestingly, any amount of water can trigger an attack. This means not only a dip in the pool or your morning shower, but also tears, sweat, and even saliva. In severe cases, it can trigger a life-threatening systemic reaction with difficulty breathing and swallowing.

Aquagenic urticaria can sometimes be prevented in these patients by coating their skin with petrolatum (plain vaseline) before exposure to water. It can also been treated with antihistamines such as Benedryl or Zyrtec.

Regular urticaria (hives), in contrast to the aquagenic type, are common. They usually present as very itchy, pink welts that make annular (circle-like) or figurate (number-like) shapes. The rash usually lasts for a few hours and in most people it is temporary. This can be quite difficult to treat and can be an almost unbearable plague for the victim.

Much to my frustration, there are many things that can trigger urticaria in patients, including:

• Medications
• Foods
• Food Additives (especially yellow food dye)
• Infections
• Emotional stress
• Menthol
• Some cancers
• Airborne elements (pollen, dust mites, aerosols, molds)
• Alcohol

Some urticarias are caused by physical triggers. They’re called physical urticaria (easy test answer). They include:

• Dermatographism – physical scratching of the skin that results in welts
• Cold urticaria – exposed areas of skin, such as hands and face develop hives in cold weather
• Heat urticaria – occurs within 5 minutes of exposer to high temperatures
• Solar urticaria – caused by sunlight
• Pressure urticaria – hives result 3 to 12 hours after prolonged pressure on the skin
• Exercise urticaria – hives develop 5 to 30 minutes after beginning exercise
• Vibratory urticaria – just like it sounds.
• And lastly, aquagenic urticaria

You might also like: Toasted Skin Syndrome

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An excellent study done several years ago published the the Journal of the American Academy of Dermatology showed that although 10-15% of people with dermatitis (an itchy skin rash) blame laundry detergent, less than 1% of patients who were tested actually had an allergy to detergent.

Most people who have an itchy rash don’t really have an allergy at all; there are many causes of itching, including dry skin, medications, bug infestations, etc. Therefore, the percentage of people with an itchy rash who are actually allergic to their laundry detergent is probably much less than 1%.

Of course, there are some people who do have an allergy to some component in their detergent such as the fragrance or bleaching agent, but this is rare.

So, before you chuck all your laundry detergents and change to a fragrance free or an “all natural” product to stop your itching, remember that this is unlikely the cause of your rash.

Instead, invest in a good moisturizer and apply copiously and often. If the problem persists, see your physician.

In particular, chronic hand dermatitis has been associated with eating foods high in nickel in patients with a known allergy. If you are allergic to nickel and have a chronic rash, especially of your hands, then consider a nickel-free diet. Try to avoid:

• Chocolate
• Potatoes
• Salmon
• Nuts and Legumes (beans, lentils)
• Any canned food or canned fruit
• Hot water from the tap
• Anything acidic (like tomatoes) cooked in a stainless steel pan
• Leafy green vegetables

The patch test showed he was 3+ positive (that’s very positive) for carba mix, compounds used in the manufacturing or rubber. “That’s impossible,” he said. “Why?” I asked. “Because I’ve worked in a tire store my whole life,” he replied.

It is a pervasive misconception that if you have been using a product like a lotion, or been in contact with something like rubber, or even taken a medication like aspirin for a long time that you cannot be allergic to it. That’s false. You can become allergic to it.

In order to be allergic to something, like rubber, you must have been exposed to it or to something very similar to it. You cannot be allergic to something you have never been exposed to. My patient was exposed to rubber without problem for years, but then suddenly his immune system targeted it, leading to his allergy. Although it is most common to develop an allergy to something that you have been exposed to recently, the allergy can develop after prolonged exposure.

The immune system is fantastically complex. It manages to determine what is foreign and harmful to you with almost flawless accuracy, but sometimes it gets it wrong. The times when it responds inappropriately to harmless chemicals in your environment is what keeps me in business.

Photo credit: Eric Castro

Nickel allergies continues to rise in young people, especially in girls; this is attributable to widespread ear and body piercings and to wearing inexpensive jewelry.

If you have an allergy to nickel, then you know it is seemingly everywhere — on belt buckles, jean snaps, jewelry, keys, cell phones, even medical devices like orthopedic hardware and vascular stents. Ironically, there isn’t much nickel in a nickel, but still enough to cause minor dermatitis on your hands or your upper thighs, especially in that uncle who always jingles the change in his pocket.

Nickel can also be found in foods such as nuts, chocolate, and fish. Eating foods high in nickel, if you have an allergy, can lead to hand dermatitis (I’ll publish a complete list of high nickel foods in a later post).

If you have an itchy rash below the belly button (from snaps and belt buckles), on your ears or face (from a cell phone or earrings), or on your wrists and fingers (from watches or jewelry), then you might have allergic contact dermatitis to nickel. In some people, the rash can become widespread, even in places where the skin has not come in contact with the nickel. This is called an id reaction.

If you think you have an allergy to nickel, then make an appointment with your dermatologist. He or she can give you a patch test to determine exactly what you are allergic to and can prescribe a topical steroid to calm your rash.