Why does inhaling grass clippings trigger an allergic reaction that causes fatigue?

From the Guidelines

Inhaling grass clippings can trigger allergic reactions causing fatigue because the clippings contain allergens that activate your immune system, leading to an overactive response that requires significant energy and can cause fatigue, as supported by the most recent study on immunotherapy for inhalant allergy 1. When you breathe in these particles, your body releases histamine and other inflammatory chemicals, which can lead to symptoms like sneezing, congestion, and watery eyes. The fatigue occurs because your body diverts resources to fight what it perceives as harmful invaders, even though these grass allergens are actually harmless.

Key Points to Consider

• Allergens in grass clippings can cause an immune response, leading to fatigue and other symptoms 1.
• Wearing a mask while mowing or handling grass, taking antihistamines like cetirizine (10mg daily) or loratadine (10mg daily) before exposure, and showering immediately after yard work can help manage these reactions.
• For severe reactions, prescription nasal corticosteroids like fluticasone (1-2 sprays per nostril daily) may help reduce inflammation, as noted in the guidelines for allergic rhinitis 1.
• Staying hydrated and getting adequate rest can also help your body recover from the energy-depleting effects of the allergic response.

Management Strategies

• Avoid exposure to grass clippings when possible
• Use protective gear like masks when handling grass
• Take antihistamines or use nasal corticosteroids as prescribed
• Shower and change clothes after yard work to remove allergens
• Stay hydrated and get enough rest to help your body recover from allergic reactions, which is crucial in managing fatigue and other symptoms associated with inhalant allergies, as discussed in the context of immunotherapy for inhalant allergy 1.

From the Research

Allergic Reactions to Grass Clippings

• Inhaling grass clippings can trigger an allergic reaction, which may lead to fatigue, among other symptoms 2.
• Allergic rhinitis, a common condition affecting approximately 15% of the US population, occurs when allergens penetrate the nasal passages, inducing an inflammatory response and production of allergen-specific IgE 2.

Symptoms of Allergic Rhinitis

• Common symptoms of allergic rhinitis include nasal congestion, rhinorrhea, postnasal drainage, sneezing, and itching of the eyes, nose, and throat 2.
• Patients with seasonal allergic rhinitis typically exhibit physical examination findings of edematous and pale turbinates, while those with perennial allergic rhinitis have erythematous and inflamed turbinates with serous secretions 2.

Treatment and Management

• First-line treatment for mild intermittent or mild persistent allergic rhinitis may include second-generation H1 antihistamines, such as cetirizine, fexofenadine, desloratadine, or loratadine, or intranasal antihistamines like azelastine or olopatadine 2.
• Patients with persistent moderate to severe allergic rhinitis should be treated initially with an intranasal corticosteroid, either alone or in combination with an intranasal antihistamine 2.

Fatigue as a Symptom

• While the provided studies do not directly address fatigue as a symptom of allergic reactions to grass clippings, they do mention that antihistamines like cetirizine and loratadine can cause somnolence as a side effect 3.
• Cetirizine, in particular, has been associated with strong signals for somnolence, attention disturbance, and other nervous and psychiatric system symptoms 3.