Food Allergy, or Something Else?

Medically Reviewed by Carmelita Swiner, MD on November 30, 2022
3 min read

It’s pretty common to have a reaction to a certain food, but in most cases it’s an intolerance rather than a true allergy. Why does it matter? Although they may have similar symptoms, a food allergy can be more serious.

These clues can help you figure out if it is an allergy or intolerance. A doctor can help you know for sure.

Food Allergy:

  • Usually comes on suddenly
  • Small amount of food can trigger
  • Happens every time you eat the food
  • Can be life-threatening

Food Intolerance:

  • Usually comes on gradually
  • May only happen when you eat a lot of the food
  • May only happen if you eat the food often
  • Is not life-threatening

A food allergy and an intolerance both can cause:

When a food irritates your stomach or your body can't properly digest it, that’s an intolerance. You may have these symptoms:

A food allergy happens when your immune system mistakes something in food as harmful and attacks it. It can affect your whole body, not just your stomach. Symptoms may include:

These triggers cause about 90% of food allergies:

The most common food intolerance is lactose intolerance. It happens when people can’t digest lactose, a sugar found in milk and dairy. Another kind of intolerance is being sensitive to sulfites or other food additives. Sulfites can trigger asthma attacks in some people.

What about a gluten allergy? While celiac disease -- a long-lasting digestive condition that’s triggered by eating gluten -- does involve the immune system, it doesn’t cause life-threatening symptoms.

Your doctor can find out if you have an allergy or intolerance. These things may help:

  • Keep a diary of the foods you eat and the symptoms you have.
  • Stop eating some foods to help figure out which one is causing symptoms.
  • Have allergy tests done.

If you have a food allergy, you'll need to stop eating the food altogether. If you have a food intolerance, you’ll need to avoid or cut back on that food in your diet. For lactose intolerance, you can look for lactose-free milk or take a lactase enzyme supplement.

With a food allergy, you could be at risk for anaphylaxis, a life-threatening reaction. Ask your doctor if you need to carry epinephrine shots (AdreniclickAuvi-QEpiPen, a generic, or Symjepi) which you could give yourself in an emergency. If so, always carry two injections with you.

  • Learn which foods -- and how much -- cause you to have symptoms. Either avoid the food or only have as much as you can without triggering symptoms.
  • When you eat out, ask your server about how your meal will be prepared. It may not always be clear from the menu whether some dishes contain problem foods.
  • Learn to read food labels and check the ingredients for trigger foods. Don't forget to check condiments and seasonings. They may have MSG or another additive that can cause symptoms.