Many people with allergies also have other health conditions at the same time. These additional health conditions are known as comorbid conditions. It is important that these co-occurring conditions are diagnosed and treated too. This is especially true if 1 condition will make the others worse without treatment.
The most common co-occurring conditions vary depending on the type of allergy. For example, hay fever and food allergies have some overlapping comorbidities but also some very different ones.
The most common co-occuring conditions with respiratory allergies like hay fever (allergic rhinitis) are:1,2
- Asthma
- Eczema (atopic dermatitis)
- Food allergies
- Sinus infection (sinusitis)
- Eye, ear, or throat infections
- Swollen esophagus (eosinophilic esophagitis)
- Enlarged adenoids
- Sleep apnea
- Fatigue
- Learning and concentration problems
The most common co-occuring conditions with food allergies include:3
- Asthma
- Eczema
- Environmental allergies
- Insect sting allergies
- Latex allergy
- Drug allergy
- Chronic hives (urticaria)
Having a food or respiratory allergy means you and your doctor may need to look out for these other conditions.
Asthma
In the United States, more than 25 million people have asthma. Of those, 6 out of 10 have allergic asthma. Allergic asthma is asthma triggered by an allergen like mold, pollen, or pet dander.4
In allergic asthma, your immune system overreacts to a substance because it thinks the substance is harmful, just like with allergies. A doctor can confirm whether you have allergic asthma using skin or blood tests.4
Though allergies and asthma are different conditions, some treatments help with both. This includes:5
- Anti-immunoglobulin (IgE) therapy like Xolair® (omalizumab)
- Allergy shots (immunotherapy)
- Leukotriene receptor antagonists like Singulair® (montelukast sodium)
Eczema
Eczema is a common allergic skin condition. Half of those with moderate to severe eczema also have asthma, hay fever, and food allergies.6
With eczema in infants and children, a rash usually forms on the scalp, knees, elbows, and cheeks. In adults, the rash usually occurs on wrists, elbows, knees, ankles, face, and neck. Eczema is strongly linked with other allergies.6
Eye infection (allergic conjunctivitis)
Allergic conjunctivitis is an eye allergy that usually occurs with hay fever. It is fairly common. Symptoms include:7
- Eye redness
- Itching or burning eyes
- Watering eyes
- Swollen eyelids
- Feeling of dirt in the eye
- Runny nose
- Sinus headache
- Brief episodes of blurry vision
When eyes get red from things like dirt, smoke, or chlorine, this is not allergic conjunctivitis. This is eye irritation. Allergic conjunctivitis is usually caused by allergens getting into the eyes. It may be triggered by dust mites, pet dander, pollen, or mold.7
Allergic conjunctivitis is a different type of eye infection from pink eye. Pink eye may look the same and cause similar symptoms, but it is caused by a virus or bacteria. Pink eye is very contagious. Allergic conjunctivitis is not contagious.7
Sleep apnea
Sleep apnea is a common sleep disorder of people with hay fever and sinus infections. It causes breathing to be interrupted for short periods during sleep. These periods last for at least 10 seconds. Those with sleep apnea often snore loudly or make gasping, choking noises while sleeping.8
Sleep apnea leads to low oxygen levels in the blood and poor quality sleep. Untreated sleep apnea can lead to high blood pressure, heart disease, diabetes, kidney disease, and depression.8
Eosinophilic gastroenteritis
Eosinophilic gastroenteritis is a rare digestive disease. However, it is more common in people who have a family history of allergies, especially food allergies. Eosinophils are white blood cells. Gastroenteritis is inflammation of the gastrointestinal (GI) tract.8
There is generally also an increase in white blood cells in the blood. Other symptoms can include:8,9
- Nausea
- Heartburn
- Trouble swallowing
- Vomiting
- Diarrhea
- Abdominal pain
If you have allergies and other health conditions, talk to your doctor. They can help ensure you get the right treatment for all of your symptoms and conditions.