Food allergies can be frustrating -- even deadly in some cases.

If you're an adult who is allergy-free, you may think that you don't have to worry about food allergies at all.

Unfortunately, this isn't the case.

Most food allergies start in childhood, but they can develop at any point in one's lifetime.

Adults might get an allergy to a food they used to eat without any problem.

And a child might outgrow an allergy only to have it reappear later in life.

According to Mayo Clinic, researchers are unsure of the reasons.

Experts there say the most common food allergies in adults are peanuts and tree nuts, fish and shrimp or lobster.

If you develop an allergy, you have to avoid eating that food.

Some people are at risk for a life-threatening reaction that requires immediate treatment.

Symptoms of an allergic reaction include:

• digestive problems
• hives
• facial swelling
• trouble breathing

And just because in the past you may have found a reaction to be mild -- it doesn't mean it couldn't be more severe in the future.

Consult your doctor to determine what's causing the problem -- and develop a plan to work with it.