Ask Doctor Cory.

Dr. Cory:

Why do we have to take a needle?

Hannah Haile Houston, Texas

Dr. Cory:

I hate shots. Every time I get a shot I squeeze my hand tightly until the shot is over. But now I still have more hepatitis shots left to go. What should I do? Also, what is the purpose of shots? How do they get in my system, and what do they do when they are there?

Meredith Hux Jacksonville, Florida

Dear Hannah and Meredith:

We can't think of anyone who likes getting a shot or being stuck with a needle. However, shots help prevent many serious diseases and sometimes give necessary medications. Unfortunately, our strong digestive juices destroy most vaccines taken by mouth. When a vaccine is given in the form of a shot, it allows the vaccine to get into the bloodstream quickly. There, the vaccine causes your body to build protection against the disease in the future.

Research doctors are coming up with easier ways to give vaccines. They hope a new vaccine that helps prevent influenza, or flu, will be available to the public soon. This vaccine is sprayed into the nose.

The other good thing about vaccines is that as you get older, you don't need as many of them. When you do need a shot, try blowing as if you are blowing bubbles while the shot is being given. Researchers have found that this blowing action makes shots less painful. It also seems to help during other short periods of pain. Try it the next time you have to have a splinter removed.

Dear Dr. Cory:

How come when you eat ice cream too fast, your head starts to hurt for a minute?

Amanda Tomlinson Binghamton, New York

Dear Dr. Cory:

How do you get brain freeze when you drink something cold?

Samantha Sledge Roanoke, North Carolina

Dear Dr. Cory:

What causes a brain freeze? Whenever l eat cold stuff, I get a brain freeze.

Ashley Farmer Chochilla, California

Dear Ashley, Samantha, and Amanda:

The type of headache sometimes known as "brain freeze" is quite common. Often the pain is a stabbing feeling that starts in the middle of the forehead. You can also feel it behind the eye or on the side of the head. The pain rarely lasts for more than two minutes.

Neurologists, doctors who specialize in the care of the nervous system, think it may be related to the nerves in the roof of the mouth. The nerves might be reacting to the sudden cold feeling. Cold normally makes our blood vessels become narrow. When the blood vessels become narrow, less blood is brought to the surface. This keeps the body from losing heat. The sudden cold of ice cream on the roof of the mouth may cause narrowing of the blood vessels in parts of the head. This, in turn, could trigger the headache.

To avoid this feeling, you may want to keep cold foods from touching the back of the roof of your mouth.

Sincerely,

Cory SerVaas, M.D.

Send your health questions To: "Ask Doctor Cory," U*S*Kids, P.O. Box 567, Indianapolis, IN 46206. Or, e-mail your questions to: [e-mail] This column does not replace your doctor's advice.