If you have seasonal allergies, you’re all too familiar with symptoms such as a stuffed-up nose (rhinitis) and itchy eyes.
If you also have irritable bowel syndrome (IBS), you may have noticed that your gastrointestinal symptoms worsen during allergy season.
Research has suggested a causal link between IBS and atopic (allergic) conditions, including allergic rhinitis (hay fever).
Read on to find out how IBS and allergic rhinitis may be connected.
Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder that comes from problems with how your brain and gut work together. IBS is characterized by symptoms such as:
- abdominal pain
While controversial, a subgroup of IBS is referred to by some researchers as
They may also include hives and other allergic skin manifestations. Common IBS symptoms associated with allergic rhinitis are abdominal pain, diarrhea, and gastric discomfort.
A stuffy nose is a common symptom of allergic rhinitis, also known as hay fever.
Common triggers include aeroallergens such as:
- dust mites
- pet dander
Aeroallergens are microscopic particles that reach the respiratory tract through inhalation. They can also reach the gastrointestinal tract through ingestion.
If you’re allergic to these or other substances, your immune system overreacts by releasing histamine when you come in contact with them. This causes symptoms such as:
- nasal congestion (stuffed up nose)
- runny nose
- sinus pain
- itchy or swollen eyes
- itchy or sore throat from a postnasal drip
- difficulty breathing
The connection between IBS, allergies, and allergic symptoms is not completely understood. The role of mast cells, which release histamine, may be a factor.
Mast cells are a type of white blood cell. They’re found throughout the body in connective tissue. Many mast cells are located under the skin. They’re also found in the intestines.
When mast cells detect an allergic substance, they release histamine. This triggers a cascade of symptoms, including a stuffy nose.
In the gastrointestinal tract, mast cells can trigger IBS symptoms when you eat or drink something you’re allergic to. They may also react to aeroallergens that reach the gastrointestinal tract through ingestion.
It’s not known whether allergies worsen IBS or whether IBS worsens allergies. However, several studies have found that a significant percentage of people have both conditions.
A 2020 clinical review found that children with allergies were more likely to have IBS as adults.
If you have IBS and allergic rhinitis, your conditions may be treated with different strategies and medications.
Your doctor will recommend identifying and eliminating your triggers for both conditions:
- For hay fever, this may include staying indoors when pollen counts are high and using a vacuum cleaner with a HEPA filter.
- For IBS, this may mean eliminating IBS trigger foods, such as gluten, dairy, and FODMAPs.
Treatments for hay fever include:
- over-the-counter medications, such as antihistamines and decongestants
- nasal saline irrigation to treat a stuffy nose
- steroid nasal sprays
- eye drops for itching eyes
- allergy shots
Treatments for IBS include:
- over-the-counter medications such as antidiarrheals, laxatives, and fiber supplements
- anticholinergic medications for bowel spasms
- tricyclic antidepressants that reduce pain
- IBS prescription drugs such as linaclotide (Linzess) to alleviate IBS-related constipation
IBS symptoms and hay fever (allergic rhinitis) are connected, though the exact causes and reasons why remain unclear.
Some research indicates a connection between allergies and IBS. People with allergic symptoms, such as a stuffy nose or hives, may also have IBS symptoms. It’s not yet known whether either of these conditions worsens the other.
Both IBS and hay fever can be treated with at-home remedies, lifestyle alterations, and prescription medications.