From people shunning gluten who may not need to, to those mistakenly skipping the flu shot because of an egg allergy, myths about allergies are common, and sometimes even believed by doctors.
After hearing the same incorrect information over and over, Dr. David Stukus, a pediatric allergist at Nationwide Children's Hospital in Columbus, Ohio, said he decided to investigate where such myths came from, and why they are so prevalent.
"These misperceptions are quite common in the general public —as well as among primary care physicians," Stukus said.
He found there was lack of scientific evidence for many ideas regarding allergies, and a lot of misinformation circulating on the Internet, he said.
"If somebody is investigating on their own, they may be steered in the wrong direction by what seems like a reliable website," Stukus told LiveScience.
Another reason myths persist is that although certain beliefs have been refuted by science, the correct information hasn't yet permeated our culture, said Stukus, who is presenting his findings today (Nov. 7) in Baltimore, at the meeting of the American College of Allergy, Asthma and Immunology.
Here's a look at some of the most common myths about allergies, and the truth behind them.
Allergic to artificial dyes
People attribute many symptoms such as chronic hives or even asthma to being allergic to the artificial coloring used in foods. It's even quite common to blame behavioral problems even ADHD on artificial dye, Stukus said.
However, there is no scientific evidence that artificial dyes cause these symptoms, he said. [ 8 Strange Signs You're Having an Allergic Reaction ]
"A lot of people actually list this as an allergy on their official medical record, which makes it very difficult to prescribe certain medication, and that really alters the effect of therapy they can receive and cause unnecessary cost," Stukus said.
Egg allergy and flu shots
People who are allergic to eggs may think they need to skip the seasonal flu vaccine.
But the truth is that vaccines are safe for people with egg allergies, even though they may contain very low amounts of egg protein because the virus is often grown in hen's eggs.
The safety of flu vaccines for allergic people became an important issue during the 2009 swine flu pandemic.
"Since then, there's been at least 25 well-conducted clinical trials that have shown the vaccines do not contain a significant amount of egg protein, and that they are very safe to give to people with egg allergy," Stukus said.
Seafood allergies and CT scans
There's a misconception that people with seafood allergies are at increased risk for negative reactions to the iodine that is sometimes used as a "radiocontrast agent" during CT scans for better imaging.
As to how this myth began, Stukus said, "this one was created by the medical establishment, about 40 years ago."
In a 1975 study, researchers observed that 15 percent of patients who experienced bad reactions to a radiocontrast agent also reported being allergic to shellfish. The researchers surmised that iodine in both shellfish and the agent may be to blame.
But nearly the same number of patients in the study had reported allergies to other foods, such as milk and eggs. [ 9 Weirdest Allergies ]
"Iodine cannot cause allergy, it's present in our bodies and in table salt," Stukus said. "People allergic to shellfish are allergic to a specific protein," that isn't present in the radiocontrast agents.
And doctors may still be propagating the myth. A 2008 study in the American Journal of Medicine found that nearly 70 percent of radiologists and cardiologists asked their patients about seafood allergies before administrating radiocontrast agents, and many of them altered the procedure for people allergic to shellfish.
Allergenic foods and babies
It is commonly thought that foods such as nuts and fish shouldn't be given to children until 12 months of age, based on guidelines issued in 2000 by the American Academy of Pediatrics.
However, the organization changed its guidelines in 2008 due to lack of evidence, and said children can eat such foods starting at age 6 months (as long as they pose no choking hazard).
"But the guideline that was established 13 years ago is still being followed today by primary care physicians, as well as the general public," Stukus said.
In fact, there's emerging evidence suggesting that early introduction of potentially allergenic foods may be good for children, and promote their tolerance. "Studies are going on trying to prove this. We don't have great evidence on that either but it's accumulating," Stukus said.
However, he noted that the new guidelines may not apply to children in families with a strong history of food allergies.
Being "allergic" to gluten?
Gluten "allergies" don't really exist. It's another wheat protein in bread that some people can be allergic to, Stukus said.
But people can have gluten intolerance, or celiac disease, an autoimmune condition in which eating some foods causes inflammation and various symptoms.
Another gluten problem is called non-celiac gluten sensitivity. "People report symptoms, and have vague complaints, but there's no objective sign, or a diagnostic tool to confirm it," Stukus said.
Unfortunately, there is no such thing as a truly hypoallergenic dog or cat, Stukus said.
In reality all pets secrete some allergens in their saliva, sebaceous glands and perianal glands. (It's not the fur that triggers allergies.)
However, some breeds are less bothersome for allergy sufferers than others.
At-home blood tests
At-home blood tests do not reveal what people are allergic to, Stukus said.
Although such tests might reveal sensitization, people who are sensitized to a certain allergen, such as milk, aren't necessarily allergic.
These screening tests are not reliable and can often lead to misinterpretation, diagnostic confusion and unnecessary dietary elimination, Stukus said.