Differentiating between tree, grass, and weed pollen.
Medically reviewed by Dr. Sarah Jenkins, MD, FACAAI
Verified ReviewerBoard Certified Allergist & Immunologist · Clinical Allergy, Asthma & Immunology
Stanford University School of Medicine
Our editorial process: All content on WhatAreAllergies.com is written by medical writers and reviewed by board-certified allergists and immunologists. We follow ACAAI, AAAAI, WAO, and ARIA clinical guidelines. Content is updated on an annual review cycle or when major guidelines change. We do not accept advertising influence on editorial content. Read our editorial policy →
Plants that rely on the wind to distribute their pollen are the primary culprits for allergies. Their pollen is lightweight, buoyant, and produced in massive quantities. Brightly colored flowers pollinated by insects rarely cause allergies.
| Pollen Type | Peak Season |
|---|---|
| Tree Pollen | Early Spring (March - May) |
| Grass Pollen | Late Spring/Summer (May - July) |
| Weed Pollen (Ragweed) | Late Summer/Fall (August - First Frost) |
Medically reviewed guides recommended for you
Dr. Sarah Jenkins, MD, FACAAI
Board Certified Allergist & Immunologist
Clinical Allergy, Asthma & Immunology
Dr. Michael Chen, MD, PhD
Clinical Immunologist & Researcher
Translational Immunology, Biologic Therapies
All contributors hold active board certification in allergy, immunology, or a related specialty. View full credentials →
Sampson HA, et al. "Second symposium on the definition and management of anaphylaxis: Summary report" — Journal of Allergy and Clinical Immunology.
View sourceAmerican College of Allergy, Asthma & Immunology (ACAAI) "Allergy Facts and Figures" — ACAAI Clinical Resources.
View sourceWorld Allergy Organization (WAO) "White Book on Allergy — 2025 Update" — World Allergy Organization.
View sourceNational Institute of Allergy and Infectious Diseases (NIAID) "Clinical Guidelines for the Diagnosis and Management of Food Allergy" — National Institutes of Health.
View sourceMuraro A, et al. "EAACI food allergy and anaphylaxis guidelines: Diagnosis and management of food allergy" — Allergy — European Journal of Allergy and Clinical Immunology.
This content reflects clinical guidelines current as of the last review date shown above. Always consult a qualified healthcare provider for personalized medical advice.