Allergy symptoms typically include sneezing, watery eyes, a runny nose, or even a skin rash. Some allergens can even trigger allergic reactions known as anaphylaxis that are medical emergencies.
But can allergies cause a fever? Generally, no. Sometimes, however, allergy symptoms can make you vulnerable to a bacterial or viral infection. And a bacterial or viral infection can lead to a fever, so you can indirectly blame the fever on your allergy.
Your symptoms depend on the cause of the allergy, known as an allergen. When you’re allergic to something, whether it’s dust, peanuts, or something else, your body reacts to the allergen by producing a chemical called a histamine.
Depending on the individual and the particular allergen, symptoms can include:
- runny nose
- itchy or watery eyes
- headache or sinus pain
- sore throat
- post nasal drip
Nausea and diarrhea are common symptoms of certain food allergies. Swelling and skin rash are also signs of an allergic reaction.
Despite its name, hay fever usually doesn’t include a fever. Hay fever, known clinically as allergic rhinitis, is a broad term used to describe an allergy to things in the environment such as pollen, mold spores, and grass.
When an allergic reaction is so severe that your breathing is jeopardized and you lose consciousness or are at risk of losing consciousness, it’s called anaphylaxis. Anaphylaxis is a medical emergency that requires immediate medical attention.
When you develop congestion, regardless of the cause, the buildup of mucus in your sinuses can be a breeding ground for bacteria. When an infection takes hold, you can be hit with a fever that can last for several days.
Congestion can be the result of sinusitis, allergies, or something more serious, such as the flu virus. It’s sometimes hard to know what’s causing your symptoms, because a cold or flu can mimic many of the signs of an allergy.
Discovering exactly what’s causing your symptoms, even if they’re mild, is important. Once you know the cause of your symptoms, you can start an effective treatment plan. And, in the case of an allergy, you can take steps to prevent symptoms or flare-ups in the future.
The key, however, is a proper diagnosis.
If you suspect your symptoms are the result of an allergy, you should see your primary care doctor.
Your doctor may recommend seeing an allergist, a specialist who can perform allergy tests and diagnose the source of your reaction. An allergist can also set up a treatment plan to reduce or prevent your symptoms.
Diagnosing an allergy requires a physical exam. You’ll be asked for a detailed personal medical history. A medical history can help your allergist find a connection between your symptoms and your exposure to the allergen or allergens that may be triggering those symptoms.
Keeping a log of when you have flare-ups can really help your allergist identify a cause. For example, noting when your symptoms appeared and what seasonal changes, if any, were taking place in the same time frame can provide important clues to your doctor.
Your doctor may recommend a skin prick test to help diagnose your allergy. In this test, a tiny amount of an allergen (such as a dust mite or a particular food) is injected just under the skin. Your skin’s reaction reveals whether or not you’re allergic to that particular allergen. Sometimes a blood test is also useful for pinpointing the cause of an allergy.
If an allergy isn’t the problem, an infection may be causing your fever. Conditions such as heat exhaustion can also cause a fever.
Treating a bacterial infection usually involves taking antibiotics to eliminate a fever and other symptoms. A virus usually just needs time to resolve on its own.
Treating an allergy often involves using medications called antihistamines. These over-the-counter medicines block or lessen the amount of histamine your body produces in response to an allergen.
Allergy shots and special types of steroids may also help reduce symptoms from an allergy. If you have seasonal allergies, an annual allergy shot may help you avoid symptoms when your allergens are in bloom.
Fevers tend to be temporary responses to an infection or other cause. Once the underlying cause, such as a cold or flu, is treated, the fever should disappear.
If an allergy frequently seems to lead to a bacterial infection, avoiding contact with those allergens is your best bet to stay healthy.
If allergy shots help you, don’t skip the next one just because you’ve gone through a few pollen seasons without symptoms. Remember that the allergy shot is probably the thing that’s keeping you free of symptoms.
If your allergy is to dust, certain foods, or animal dander, you may need to make adjustments in your home environment and lifestyle. If pollen is the culprit, pay close attention to air quality reports and forecasts for your area.
Managing a fever starts with taking an accurate temperature and knowing when a low-grade fever has advanced to one that requires medical attention.
An oral digital thermometer held under the tongue can get an accurate reading in about 40 seconds. A rectal digital thermometer for babies takes about the same amount of time.
If you have both kinds in your house, be sure to label them clearly and clean them well after each use with soap, cold water, and rubbing alcohol. Be sure to rinse the alcohol off thoroughly.
What’s often called the “normal” body temperature, 98.6° F (37° C), is actually an average body temperature. Normal body temperatures range from about 97° F (36.1° C) to 99° F (37.2° C) and sometimes more.
So, body temperature can vary about a degree higher or lower than 98.6° F without any health concerns. This is true from one person to the next as well as for one person at different times of day among other factors. (For example, your temperature tends to be lower first thing in the morning than it is later in the afternoon.)
If your temperature reaches 100.4° F (38° C) or higher, you have a fever, and it’s likely that you have an infection. You should get medical attention soon to begin treatment.
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A high fever in an infant can be a life-threatening situation. Seek immediate medical attention if your baby’s temperature approaches 102° F (38.9° C).