Cross Reactivity

An in-depth knowledge of allergen cross-reactivity is imperative when selecting allergens for immunotherapy. Because limiting the number of allergens in a vaccine preparation may be necessary to achieve the optimal therapeutic dose for each allergen, the cross-reactivity of clinically relevant allergens should be taken into account when making allergen selections. When cross-reactivity between pollens is substantial, selection of a single pollen within the cross-reactive genus or subfamily may suffice.

The recognition of distinct antigens by the same IgE antibody, cross-reactivity is demonstrable by in vivo and in vitro tests, and clinically manifests as reactions caused by antigens homologous to different species.

Led by resident botanist Dan Mork, we’ve put together a handy reference chart identifying known patterns of allergen cross-reactivity. View below or download and print.


Timothy 0831

Redtop 0777

Bent Grass, Colonial
Koeler’s Grass
Oats, Common Wild
Oatgrass, Tall

Bent Grass
Bluegrass, Kentucky & Canada

Canary Grass
Reed Canary Grass

Orchard Grass 0718

Cheat Brome
Blue Bunchgrass
Wheatgrass, Crested
Giant Wild Ryegrass
Rye, Cultivated
Rye, Alkali

Perennial Ryegrass 0787

Quack Grass
Ryegrass, Italian

Bermuda Grass 0537

Gamma Grass, Blue
Salt Grass

Johnson Grass 1745

Sorghum, Common Cultivated
Sudan Grass


Dock/Sorrel Mix 1517

Dock, Bitter
Dock, Yellow
Sheep Sorrel

Plantain, English 2213

Plantain, Narrowleaf
Plantain, Broadleaf

Lambs Quarters 1787


Ragweed Mix (Giant, Short & Western) 2318

Giant Ragweed 2294

Short Ragweed 2297

Ragweed, Slender


Western Ragweed 2309

Beach Bur
Ragweed, Bur/Rabbit Bush
Ragweed, Canyon
Ragweed, Desert
Ragweed, False
Ragweed, Silver

Kochia 1781

Mexican Tea
Jerusalem Oak

Carelessweed/Pigweed Mix 1301

Pigweed, Spiny
Waterhemp, Western
Prostrate Pigweed

Scale, Wing 2483

Iodine Bush
Winter Fat

Sage, Mugwort 2414

Sage, Wormwood
Sage, Coast
Sage, Fringe
Sage, Pasture
Sage, Tarregon/Green


Acacia, Golden 1007

Acacia, Bailey’s

Alder, Red 1019

Alder, Mountain
Alder, Sitka
Alder, White

Ash, White 1061

Ash, Arizona
Ash, Green
Ash, Oregon

Birch Mix 1169

Birch, Cherry
Birch, Paper
Birch, River/Red
Birch, Spring
Birch, White
Birch, Yellow
Chesnut, American
Hazelnut, American
Hazelnut, European
Hornbeam, American

Boxelder/Maple Mix 1214

Chesnut, Horse
Maple, Coast
Maple, Red
Maple, Soft Silver
Maple, Sugar

Cedar, Mountain 1337

Arborvitae, Oriental
Cedar, Giant/Western Red
Cedar, Incense
Cedar, Japanese
Cedar, Rocky Mountain
Juniper, California
Juniper, Chinese
Juniper, One-seed
Juniper, Pinchot
Juniper, Utah
Juniper, Western

Cypress, Arizona 1451

Cedar, Port Orford
Cypress, Italian
Cypress, Monterey

Cottonwood 1436

Cottonwood, Black
Cottonwood, Fremont
Poplar, Balsam
Poplar, Lombardy
Poplar, White

Oak Mix 2036

Oak, Arizona, Gambel
Oak, Arizona Scrub
Oak, Blackjack
Oak, Bur
Oak, California Black
Oak, California Scrub
Oak, Coast Live
Oak, Englemann
Oak, Garry/Oregon
Oak, Holly
Oak, Interior Live
Oak, Post
Oak, Swamp/Pin
Oak, Valley
Oak, Virginia Live
Oak, Water

Elm, America 1541

Elm, Chinese 1547

Elm, Fall-Blooming

Elm, Siberian
Elm, Slippery

Pecan 2099

Hickory, Shellbark
Hickory White

Pine Mix (LY) 2204

Pine, Austrian
Pine, Digger
Pine, Loblolly
Pine, Monterey
Pine, Pinyon
Pine, Red
Pine, Shortleaf
Pine, Virginia Scrub
Pine, Eastern White
Pine, Western White

Sycamore, American 2564

Sycamore, Mapleleaf
Sycamore, Western

Walnut, Black 2627

Walnut, Arizona
Walnut, Hind’s California Black
Walnut, English

Willow, Black 2678

Willow, Arroyo
Willow, Pussy
Willow, Red
Willow, Yellow


This guide illustrates the cross reactive qualities of some grasses, weeds, and trees from the HollisterStier pollen allergen lines. If you have more questions on cross reactivity please contact our customer service center to be connected with our botantist. To make identifying the correct HollisterStier product, the item number of the allergen is provided to reference when posing questions or placing orders.

To use the guide please note that the allergens listed in column 1 can be used to treat allergies to any of the listings in columns 2 and 3. In column 2 the allergens noted with teal arrows direct you to the groups within column 3 that can also be treated using that particular extract.

See full prescribing information for complete boxed warning.

  • Intended for use only by licensed healthcare provider experienced in administering Non-Standardized Allergenic Extracts and trained to provide immediate emergency treatment in the even of a life threatening reaction.
  • Non-Standardized Allergenic Extracts can cause serious systemic reactions, including anaphylactic shock and death.
  • Do not inject intravenously.
  • Initial dose for immunotherapy must be individualized based on the degree of sensitivity of the patient.
  • Observe patients for at least 30 minutes following administration.
  • Immunotherapy may not be suitable for patients with medical conditions that reduce their ability to withstand a systemic reaction.
  • Non-Standardized Allergenic Extracts can cause serious systemic reactions, including anaphylactic shock and death, especially in patients who have severe or steroid-dependent asthma, cardiovascular disease, or in patients who use beta blockers.
  • Local reactions at the injection site include: erythema, swelling pruritus, tenderness and pain.
  • Systemic reactions include: generalized skin erythema, urticaria, pruritus, angioedema, rhinitis, wheezing, laryngeal edema, and hypotension.