Many people have allergies without knowing it. Allergic reactions can be mild, moderate, or severe. Allergic reactions aren't always consistent, but they can get worse over time. Insider spoke with Dr. Purvi Parikh — an allergist, immunologist, and spokesperson for Allergy and Asthma Network — to learn the signs of an allergic reaction. Visit Insider's homepage for more stories like this.
Allergic reactions account for 200,000 visits to US emergency rooms every year, according to the Asthma and Allergy Foundation of America. Often times this is due to the fact that some people aren't aware they are allergic to something until they have an asthma attack or anaphylaxis, a life-threatening allergic reaction. Allergies happen when the immune system overreacts to a particular substance. After exposure to an allergen, the body stacks up its defense system by producing a chemical called histamine. Whether the trigger is in pet dander, peanut butter, or a bee sting, these histamines cause people with allergies to experience a wide range of symptoms. "You can take two people who have the same exact allergy, and one can be very severe while one can be very mild," says Dr. Parikh, allergist and asthma associate of Murray Hill in New York City. So how can you tell if you're allergic to something in the first place? The only way you can be 100% certain is by getting an allergy test, but until that happens, it's important to be mindful of the signs of a possible reaction so that you can be prepared if one occurs unexpectedly.Itching, rash, and hives are also common symptoms of contact dermatitis.
Contact dermatitis is a type of allergic reaction that appears on the skin several hours after physical contact with an allergen. According to Cleveland Clinic, everyday items like sunscreen, perfumes, jewelry, and cosmetics are known to cause this reaction in people who are allergic. In many cases, the rash or hives will begin at the exact spot where the allergen first touched your body, though it can spread to other places. For instance, if you're allergic to the gold in your necklace, you're probably going to experience some itchiness and redness near your neck. Likewise, if you are allergic to the additives in your leather belt, you'll probably feel itchiness around your abdomen. Contact dermatitis reactions aren't typically as severe or life-threatening as allergic reactions to a food or drug can be. However, they can still interfere with your life, which is why an allergy test can be helpful to avoid potentially serious reactions in the future. If you experience itching, welts, or hives after eating certain foods, you may have a food allergy.
"Almost all allergies are associated with some type of skin symptom, especially food allergies," Dr. Parikh told Insider. "This can be anything from itching in your skin, your tongue, and your throat, to hives, eczema or redness." Eczema is red, itchy inflamed skin, whereas hives are raised welts that appear in clusters. Dr. Parikh said it's important to note that the presence of skin-related symptoms (like a rash) is one of the biggest differences between food allergies and food intolerances. This is because allergies activate your entire immune system, whereas an intolerance may only affect certain areas like digestion. "There are skin symptoms in almost 90% of allergic reactions to food," Dr. Parikh told Insider. In other words, while something like lactose intolerance may cause you to experience symptoms such as gas or bloating, you probably won't develop hives if you drink a small amount of milk. On the other hand, if you have a hazelnut allergy and take even a bite of some chocolate hazelnut toast, you may expect to develop welts all over your face, arms, stomach, and legs. Skin reactions to food can occur as soon as a few minutes after eating the allergen, though sometimes they can take hours to appear. And to make matters more complicated, sometimes you won't experience severe hives the first time or even every time you interact with the food, says Dr. Parikh. "Sometimes a reaction can get worse the more you keep eating it," she said. "Because food allergies are more likely to cause the more dangerous, anaphylactic reactions, we still tell people with mild reactions to avoid that particular food. We can't predict when it will be severe versus not." This is why it's a good idea to visit your doctor even if you experience mild symptoms after eating. Watery eyes are often a defining symptom of an allergic reaction.
Do your eyes well up every time you're around your neighbor's cat? Chances are it's not because you're emotional. Pet dander is one of many allergens that are known to cause allergic reactions in the form of itchy, watery eyes. Other substances like the ingredients in your contact lens solution or even the perfume in an air freshener can cause you to rub your lids and reach for the eye drops. Watery eyes are often a sign that other symptoms you have — like a runny nose — are allergy-related. The good news is allergists can conduct a special skin test to let you know exactly what your triggers are. They can also give you a special shot which can make your allergy symptoms less severe. You might have an allergy if you're coughing, wheezing, and experiencing other asthma symptoms.
"People may not realize asthma symptoms can be a sign of a reaction, too," says Dr. Parikh. "If you have itchy skin, and you're also wheezing or coughing, this could be a sign that you're having not only a reaction to a particular food, but a more serious one." You may associate wheezing (a whistling sound upon breathing in and out) with allergic rhinitis symptoms, which aren't life-threatening. These allergies occur in an estimated 78% of people who are asthma patients. But this type of reaction doesn't only happen with allergies you inhale like pollen, dust mites, or dander. In fact, you can have asthmatic symptoms within minutes of eating foods you might be allergic to or after being bitten by an insect. Sometimes it can even be a sign of anaphylaxis. "People who already have underlying asthma — whether it's caused by pollen or exercise-induced asthma — are at risk for having more deadly reactions to foods," Dr. Parikh told Insider. "There have been food allergy-related deaths because people didn't know their asthma was a sign to use their epinephrine auto-injector." This is why it's critical to get an allergy test if you already have asthma, regardless of how severe your condition is. Itchy mouth and throat can be a sign of both food allergies and seasonal allergies.
When histamines are activated in the nasal passages, it triggers congestion. This can cause excess mucus to drain into the back of your throat, which creates an uncomfortable tickling sensation. In addition, inhaling allergens can irritate the lining of the throat. And it's not just airborne allergies that cause this type of reaction. According to the Mayo Clinic, food allergies are known to cause swelling and itchiness inside the mouth, too. Some people may not experience this symptom every time they eat the food that's tied to an allergy. For example, people who have oral allergy syndrome are known to experience reactions to raw fruit or vegetables, but only during specific times of the year. Whether your reactions are mild or severe, you should still avoid triggers, says Dr. Parikh. A severe food or drug reaction can cause swelling throughout your entire body.
Histamines can cause multiple areas of your body to swell. This type of reaction can occur visibly on the skin as well as places you can't see, like inside the throat. Dr. Parikh says that tongue swelling and breathing problems are both signs of a moderate-to-severe allergic reaction to food. Swelling inside the throat should not be taken lightly because if left untreated, it can completely block a person's airway and make it impossible to breathe. Vomiting, diarrhea, and severe stomach cramps can indicate an allergic reaction to a food or drug.
Most of us associate throwing up with viral gastroenteritis (aka the stomach flu), but sometimes severe stomach symptoms are actually a sign you're experiencing a reaction to a particular food or drug you've ingested. "People may not realize severe stomach cramps, vomiting, or diarrhea that is accompanied by skin symptoms are signs of a severe allergic reaction to foods," Dr. Parikh told Insider. "Vomiting is actually a trigger to use an emergency epinephrine pen." Some serious allergic reactions can cause lightheadedness.
"Dizziness and loss of consciousness are warning signs that you're having a more serious reaction," said Dr. Parikh. This is common in severe allergies to food like peanuts, tree nuts, and eggs, as well as bee stings and spider bites. When the body releases a large number of histamines in response to an allergen, it causes the blood vessels to widen. This can lead to a sudden, dramatic drop in blood pressure, which can send you into a dizzy spell and even cause you to faint. If this happens to you (or your child), you should seek emergency medical attention, regardless of whether there is visible evidence of an allergic reaction like hives. The American Academy of Allergy, Asthma & Immunology notes that life-threatening anaphylaxis can still occur without a person experiencing skin symptoms.
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