Can Allergies Cause Fever A Comprehensive Guide


can allergies cause fever

People can develop allergies at any age, though they often begin in childhood. Genetics and environment also play an important role.

How Can Allergies Cause Fever?

Allergies themselves don’t directly cause fever. Fever happens when the body’s immune system responds to infectious invaders like bacteria and viruses. So how can allergies lead to a fever? Here are the main ways:

  • Sinus Infection: Chronic allergies can cause sinus inflammation and congestion. This provides the ideal breeding ground for bacteria, leading to a bacterial sinus infection which causes fever.
  • Respiratory Infection: Allergic asthma or inflammation makes the lungs more vulnerable to viruses and bacteria. A respiratory infection like bronchitis may occur, spurring a fever.
  • Body’s Confused Response: Sometimes the body mistakes allergy cells and proteins for harmful invaders. This prompts an exaggerated immune reaction and inflammation that raises the body’s temperature.
  • Vasomotor Rhinitis: This allergy-triggered condition causes blood vessel swelling in the nose. The swelling prevents heat from escaping the body easily, leading to a mild fever.

When to Suspect an Allergy-Related Fever

Wondering if your fever could be linked to allergies? Consider these signs:

  • Fever is low-grade (less than 101°F)
  • Onset of fever coincides with allergy symptoms like nasal congestion or cough
  • Symptoms worsen with allergen exposure, like going outside or sleeping in a dusty room
  • You have a history of seasonal or perennial allergies
  • Fever lasts only a few days and resolves without treatment

If the fever pattern keeps syncing up with your allergy flares, allergies could very well be the culprit. Keep a symptom diary to help connect the dots.

Other Causes of Fever to Rule Out

While allergies can occasionally cause fevers, more serious infections need to be ruled out too. These include:

  • Flu
  • COVID-19
  • Strep throat
  • Ear infections
  • Urinary tract infections
  • Pneumonia
  • Mastoiditis
  • Meningitis

The flu, COVID, and bacterial infections often lead to high, persistent fevers over 101-102°F, along with body aches and chills. Seek medical care promptly if you have these red flags to get proper diagnosis and treatment. Don’t assume it’s just allergies.

Telling the difference between allergy and infection fevers isn’t always straightforward. Doctors perform physical exams and tests like throat cultures and x-rays to pinpoint the exact cause. But some overlap in allergy and infection symptoms does exist.

Role of Antihistamines and Allergy Medications

Antihistamines like Zyrtec, Allegra, and Claritin can provide relief from various allergy issues. By blocking histamine activity, they tackle:

  • Sneezing and nasal discharge
  • Itchy/watery eyes and throat
  • Hives and skin flushing

So can antihistamines also treat allergic fevers by calming inflammation levels? Possibly, yes. But don’t rely solely on over-the-counter antihistamines to manage allergy-related fevers. Their fever-reducing powers are limited compared to actual fever medications like acetaminophen or ibuprofen.

Lifestyle Measures to Control Allergy Fevers

Aside from medications, these self-care tips can help tackle allergy-related fevers:

  • Use air filters and vacuum regularly to limit dust mites
  • Wash bedding weekly in hot water to reduce allergens
  • Wear a mask outside during high pollen counts
  • Schedule allergy shots for relevant sensitivities
  • Rinse pollen out of hair after spending time outdoors
  • Take showers and change clothes after reactions
  • Stay hydrated and get enough sleep

Implementing some prevention strategies offsets the cascade effect from allergies to worsening symptoms like possible fevers.

When to See a Doctor

Consult your doctor if any of the following apply:

  • Fever higher than 101-102°F
  • Fever lasts over 3 days without improvement
  • Severe headache, body aches, dizziness, or swollen lymph nodes
  • Breathing difficulties or chest pain
  • Symptoms significantly interfere with daily function

Make an appointment sooner if the fever seems related to an acute infection rather than just allergies. Prompt diagnosis and treatment help prevent complications.


While allergies themselves do not directly cause fevers, they can sometimes lead to secondary issues like sinus infections, respiratory infections, and confused immune signaling that prompts a low-grade fever reaction. The fever serves as the body’s response to perceived inflammation and invaders.


Can allergies directly cause a fever?

No, allergies themselves don’t directly spark fevers. They cause issues like congestion and inflammation. Secondary complications like sinus infections, respiratory infections, or confused immune signaling then trigger a low-grade fever.

Why do my allergies keep causing fevers?

If your allergies frequently lead to fevers, you may not be controlling allergy symptoms adequately or avoiding triggers properly. Chronic unchecked allergies create prime conditions for secondary bacterial or viral infections to take hold, spurring a fever response.

How high of a fever can allergies cause?

Allergy-related fevers are usually low-grade, less than 101°F. Higher, more persistent fevers above this suggest an underlying infection that requires accurate diagnosis and medical treatment.

Can I take anything for an allergy fever?

Yes, over-the-counter antihistamines can provide mild fever relief by controlling allergy inflammation levels. Allergy nasal sprays help too. Additionally use OTC fever reducers like acetaminophen or ibuprofen for optimal temperature control.

When should I worry about an allergy fever?

Consult your doctor promptly if allergy fevers exceed 101-102°F or last over 3 days without improvement. Also seek timely care for symptoms like severe headache, body aches, breathing problems, or anything interfering with normal function. Don’t dismiss fevers as just allergies.

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