MADISON, Wis. -- The simple buzz of a bee can scatter a summer crowd but for people with bee allergies, that fear is justified.

Following the death of man in Eau Claire last week because of a bee sting, some doctors are warning people to know recognize the difference between a common sting and a fatal allergic reaction.

Michael Heifetz is just one of many people who is deathly allergic to bee stings. Heifetz said that he wasn't always allergic and had been stung before that without any atypical reaction.

But as he learned, a bee allergy can suddenly develop. Heifetz discovered his about six years ago when he was attacked by a bee hive and began to have trouble breathing, WISC-TV reported.

He immediately went to the hospital, where he was admitted with anaphylaxis shock.

Since now is the time of the year when bees are the most aggressive, doctors said it's important to be able to tell the difference between a typical bee sting and a deadly allergic reaction.

"A normal person who did not have an allergy to a bee sting would have a local reason and would have pain, swelling, redness at the site," said Dr. Christian Rickman.

A person with an allergy would react differently, he said

"They'd have problems breathing or swallowing, would have real low blood pressure, could pass out and ultimately unfortunately sometimes people die of bee stings," said Rickman.

That danger is why it's important to be prepared and always carry at least one Epi-pen, health officials said.

An Epi-pen is essentially a personal life-line that anyone can inject into their own thigh. It is small enough to fit in a pocket, which is important because it needs to go everywhere with an allergic person.

"It has to be with me here at a pool, on the golf course, at a baseball game, at a picnic," said Heifetz. "Even the most routine activities, it's with me all the time."

Although an Epi-pen can stop the allergic reaction, a trip to the ER may still be a good idea because the medication can wear off.

Bee desensitization shots can help for people allergic to stings. The shots need to be taken every four to six weeks for three to five years, but even with the shots, doctors still advise patients to carry an Epi-pen, just to be safe.