10 Unusual Allergic Reactions Revealed

Oct. 3, 2008— -- There was redness and itching, some blisters and oozing. Something wasn't right with Dr. Michael Rosenthal's patient, a woman in her mid-50s.

The inflammation around her scalp pointed to some type of allergic reaction, but the patient wasn't sure what had caused it.

"Have you put anything new on your hair or head?" Rosenthal asked her.

She said she had used hair dye, but had discounted the dye as a source of the problem because the symptoms didn't arrive until more than a week after she had colored her hair. But the hair dye turned out to be the culprit.

When you use something new on your body, it might take a week or two to elicit the allergic reaction, explained Rosenthal, vice chairman of academic programs at the department of family and community medicine at Thomas Jefferson University. "Don't think that because you've been using something a long time that it can't be that."

Talk to any physician who treats allergies, and they'll liken their job to that of a police detective. Constantly on the hunt for the unknown offender, an allergy consult often seems more like a witness interrogation featuring a litany of probing questions.

Sometimes, the case is tough to crack, because you can be allergic to just about anything. Some people are even allergic to medications that are used to treat allergies, such as corticosteroids.

Still, seldom are these incidents one-of-a-kind phenomena. Even the most unexpected allergic response is likely to be duplicated in another person, somewhere.

In order to make the job easier for fellow allergy investigators, doctors will publish accounts of rare allergic reactions in medical journals and share their findings at medical conferences and on the Internet.

We've collected 10 of the most unusual allergy stories.

One problem with diagnosing the allergy is the rash could come a week after contact with nickel, so not everyone associates the symptoms with the potentially problematic object, said Jacob.

The number of allergy patients testing positive for a nickel reaction is on the rise in the United States. Many clinicians have attributed the increase, especially in men, to a growing number of ear and other piercings.

About 19 percent of patients with allergic dermatitis are sensitized to nickel, reported the North American Contact Dermatitis Group in data from 2003-2004. The number of such patients was much smaller in 1985-1990 -- about 11 percent.

How does one become sensitized to nickel? As Jacob explains it, for some people the intimate contact between the skin and the nickel used in earrings and ear posts can do the trick.

"In general, the first time you're in contact with nickel, you don't get a rash," said Jacob. But your immune system remembers the metal and eventually, after more exposure, you reach an "elicitation threshold" when "your skin is primed to react."

Jacob says she wants the American Academy of Dermatology to help push forth regulations to limit the amount of nickel in products with prolonged skin contact, just as was done in Europe in the early '90s.
Henna is a normally reddish-brown or greenish-brown vegetable coloring derived from lawsone, an ingredient found in the leaves of the henna shrub. Normal henna rarely causes allergic contact dermatitis, but darker henna containing an added chemical also found in hair dye called p-phenylenediamine, or PPD, can instigate severe skin problems and additional allergies.

In some cases, the tattooed skin of those who are allergic to PPD will swell and blister, with the contours of the bumpy skin conforming to the shape of the original tattoo.

"When they add the black hair dye at significant concentrations … we're seeing people with blistering and scarring to it," said Jacob.

It's not unusual for people who react to black henna to also react to hair dye, sometimes as a result of the black henna encounter.

While PPD in small amounts is still allowed in hair dyes, it has been banned from skin products in the United States since 1938. Still, henna artists hoping to capitalize on the popularity of the black coloring can mix the dangerous paste on their own.

"When you see somebody with a stand that says 'henna,' ask them what color the stain is when the paste comes off the skin," explained Catherine Cartwright-Jones, a retired henna artist and webmaster for the Henna Page. If the stain on your skin is black, "you've got aproblem."
"Even I was skeptical," said Dr. Harvey Leo, a pediatric allergist and immunologist at C.S. Mott Children's Hospital in Ann Arbor, Mich. "Chocolate allergies are really rare," he explained, adding that most reactions to chocolate either are not true allergic reactions or they come as a result of exposure to nuts or milk in the chocolate chunks.

However, after some persistence by Paciocco, a skin test and a food challenge showed Gabriele, indeed, hadthe allergy.

"I was shocked because I love chocolate," said Paciocco. "And I felt bad. He can't have a chocolatebar?"

In the end, both parent and doctor agreed persistence paid off in confirming an unusual and potentially dangerous allergy.

"I don't think patients should be afraid to challenge their doctor," said Leo.

"Dr. Leo and I have a really good relationship, so I feel really comfortable with him," added Paciocco. "You should always listen to that intuition."
Most often reported with running or jogging, the exercise-allergic person might get hives, swelling, trouble breathing, low blood pressure, itching, nausea, a headache or wheezing.

Because some of the symptoms occur commonly during normal exercise, some people with exercise-induced anaphylaxis might not realize they have the problem.

In addition, for some people, the reaction only comes when exercise is combined with a certain food. Casalenoted several early reports of exercise-induced anaphylaxis from people who ate celery before they exercised.

"They could exercise, they were fine. They could eat celery, they were fine. They eat celery, then they exercise -- then they have an anaphylactic reaction," said Casale, who studied the phenomenon in the 1980s.

As is typical with most allergic reactions, the symptoms of exercise-induced anaphylaxis result from chemicals -- including histamines -- that are released by mast cells in the body. But Casale said researchers have yet to figure out why exercise, or the food/exercise combination, triggers the mast cells to act.

Still, doctors say there are ways for the afflicted to exercise and stay safe. You can exercise with a buddy, carrying adrenaline, and in the case of those with food triggers, avoid meals for two to four hours before and after exercise, Casale suggested.
"If you put an ice cube on somebody that has cold urticaria, they're going to have a big welt right where the ice cube was," said Casale. And it's not just the cold. "It could be heat, could be sunlight. It could be vibration. It could be pressure."

In fact, some cases of heat-induced hives might be confused with exercise-induced anaphylaxis because exercise can raise body temperature.

Casale found the two could be distinguished for diagnosis by either heating the patient using a warming blanket or placing the patient's hand or leg in hot water. Only those with heat urticaria will develop hives.

An even smaller number of people with the condition may be diagnosed with aquagenic urticaria, meaning they are allergic to water.

"I actually saw a patient probably six or seven years ago. We put water on her and, boy, she just broke out in hives where the water hit her," said Casale, although he thought the reaction might have been provoked more so by the temperature of the water than the water itself.

There's no treatment for physical urticaria and "we still don't have a really good clue as to how [the hives] come about," said Casale. "These syndromes aren't extremely common and they're very difficult to study."
"I think most people, when they think of anaphylaxis or allergic reactions, they're thinking about insects like wasps and bees," said John Klotz, an entomologist at the University of California, Riverside. But these caterpillars exemplify the range of creatures out there that don't need to sting you to cause a reaction.

Klotz is publishing a review of reports on dozens of animals and insects, including the hairy caterpillars, that can cause a severe allergic response.

"I thought it would be a good way of heightening awareness of the problem," he said.

Deemed as forest pests in Europe, the processionary caterpillars -- named as such because they form long lines when heading into or out of their nests -- have been implicated in numerous individual and group incidents.

See Video Of Drastic Measures to Control Processionary Caterpillars in Europe

In June 2004, more than 40 people who were sitting under an infested oak tree in the region of Saarland in Southwest Germany were sickened by the caterpillars although only a few actually touched them.

"Someone could inhale them [the hairs] or ingest them, and in some cases they could penetrate the skin," said Klotz. Some children have been hospitalized after eating the creatures. "A lot of times they'll pick up something furry and curious like a caterpillar, and you know, sometimes ingest them, just out of curiosity."
"In the area where this thing is going on, tick bites are much more common than people realize," said Platts-Mills.

The ongoing research is being closely followed by other allergists intrigued by the findings.