What Are 5 Signs of a Food Allergy and How Long Does It Take to Calm Symptoms?

Food allergy symptoms can include trouble breathing, hives, vomiting, itchiness, and swelling. The treatment for food allergies is to completely avoid the food that caused the reaction. There are emergency medications that can help if you accidentally eat a food that you're allergic to.

1. Anaphylaxis 

Anaphylaxis is a severe allergic reaction that can be life-threatening. If you have any of the following symptoms of anaphylaxis, get medical help right now:

• trouble breathing or feeling short of breath
• wheezing
• tightness in your throat or chest
• tingling hands, feet, lips, or scalp
• hoarseness 
• feeling like you have a lump in your throat
• dizziness or feeling like you might faint

2. Skin rashes

An allergic reaction can make your skin flush red and itch. The redness may be in just one area, like your face, or it could spread all over your body. Food allergies can cause itchy rashes, including hives. Hives look like welts, raised bumps, on your skin. They can be red or skin-colored. If they are red, hives will turn white in the middle (blanch) when you press on them.

Some, but not all, people with atopic dermatitis find that certain foods make their eczema flare or suddenly get worse. Atopic dermatitis is a type of eczema, a long-term skin condition that causes itchiness, dry skin, redness, rashes, and scaly patches. Up to 30% of people with atopic dermatitis also have food allergies.

3. Angioedema (swelling)

As a symptom of a food allergy, swelling can occur with or without hives. Swelling without hives is less likely to be itchy, but you may feel a numb or tingly feeling right before the swelling starts. When related to a food allergy, swelling is most common in your face, hands, feet, and genitals.

4. Upset stomach 

Food allergies can cause problems with your digestive system, such as:

• stomach pain or cramping
• bloating
• diarrhea or constipation
• nausea
• vomiting

5. Itchy nose and eyes

If you're sneezing and have teary eyes, you might have allergies from something in the environment, like pollen. But food allergies can also make you sneeze more than you normally do. If you're reacting to something you ate, your nose might be stuffed up, runny, or itchy. Or your eyes may be itchy and watery (have more tears than usual).

Food allergy symptoms usually start within the first few minutes after you put the trigger food (the food that caused the reaction) into your mouth. However, symptoms can start anytime within the first two hours after eating the trigger food. Occasionally, a second reaction will start about 4 to 6 hours after you eat the trigger food. It's important to keep an eye on anyone, especially a young child, who has had an allergic reaction to watch for this second wave of symptoms.

How long the symptoms last can depend on which symptoms you have and the severity of your reaction. Hives, for instance, often disappear within 6 hours.

Your doctor or nurse may tell you to take an antihistamine such as diphenhydramine (Benadryl) to help ease mild food allergy symptoms. Diphenhydramine takes about 15-30 minutes to start helping with symptoms.

If you have chronic symptoms, meaning the problem has gone on for a long time, your doctor may ask you to try an elimination diet to help determine which foods are trigger foods for you. For an elimination diet, you avoid a particular food or foods completely for a period of time and see if your symptoms get better. It typically takes 7 to 14 days to see improvement.

If you have atopic dermatitis that flares because of a food allergy, it may take up to 3 to 4 weeks of avoiding a food trigger to ease your symptoms.

Some children outgrow their allergies, especially to milk, egg, wheat, and soy. In particular, 80% of children with allergies to cow's milk or soy outgrow their allergy by the time they turn 16. Nut and seafood allergies are less likely to go away over time.

Your immune system works to fight off germs that could make you sick. When you have a food allergy, your immune system fights the trigger food as if it were a germ. This causes symptoms like sneezing, watery eyes, and itching as your immune system attacks the food that it sees as an enemy.

Doctors have reported allergic reactions to over 170 different foods. However, there are nine foods that cause 90% of allergic reactions:

• eggs
• dairy (milk and products such as cheese and butter that are made from milk)
• peanuts
• tree nuts (such as almonds, walnuts, and pecans)
• fish
• shellfish (like shrimp, clams, and crab meat)
• wheat
• soy
• sesame

People with asthma, eczema, or hay fever are more likely to develop allergies. Allergic diseases tend to run in families. If you have a family member who has a food allergy, hay fever, asthma, or eczema, you are at a higher risk of developing a food allergy.

Allergies are twice as common in children than in adults, but allergies can start at any age. If allergies go away, they may come back later in life. Stress, smoking or being around second-hand smoke, and changes in hormones sometimes play a part in whether or not you develop allergies or how severe your allergies become.

If you have symptoms related to anaphylaxis, such as difficulty breathing, call 911. If your reaction is severe, even if your symptoms aren't on the anaphylaxis list above, get medical care right away. Severe symptoms include hives all over your body, tongue, or lips that are very swollen or vomiting over and over again.

Even if you are having milder food allergy symptoms, talk with your doctor about what you're experiencing. Some people who have mild reactions to a food later have a more severe reaction, so it's good to have a plan of action in place. If possible, go ahead and see a doctor or nurse while you're having symptoms.