Hackberry Allergy Shots: The Family-Reassigned Plains Aeroallergen
Hackberry (Celtis occidentalis) is the botanical oddity of US allergy panels: APG IV phylogeny moved it from Ulmaceae into Cannabaceae — the same family as Cannabis sativa — yet most SCIT prescriptions still group it with elms. Legacy cross-sensitization with elm persists clinically, but cross-reactivity with cannabis or hops is not documented. No IUIS-named allergen and no SCIT RCT exist for any Celtis species.
About Curex’s SCIT program
Curex’s at-home allergy shots (SCIT) are coming soon and focus on the most common environmental allergens:
- • Pollens — tree, grass, weed & ragweed
- • Pet dander — cat & dog
- • Dust mites
- • Molds — Alternaria & mold mix
Hackberryis covered here for general education and may not be part of Curex’s current treatment set. Join the waitlist and our care team will help confirm your options.
Hackberry Allergy Immunotherapy: How It Works
Allergy immunotherapy is the only long-term treatment that re-trains the immune system to stop overreacting to hackberry — rather than just masking symptoms with antihistamines or steroids. By gradually exposing the body to controlled doses of hackberry allergen, immunotherapy shifts the underlying allergic response and produces relief that often outlasts treatment by 7–10 years.
There are two evidence-based forms of hackberry immunotherapy used today, both built on the same desensitization principle but delivered very differently.
of sustained relief after a complete immunotherapy course — the only allergy treatment with proven long-term effect after stopping.
Allergy Shots (SCIT)
Weekly injections of hackberry extract in a clinic, escalating over 3–6 months until a maintenance dose is reached. Continued monthly for 3–5 years. Longest clinical track record for hackberry allergy.
- Strongest evidence base for severe and polysensitized patients
- Covered by most insurance plans
- Requires 50–100+ in-person clinic visits across the full course
- Or at home with no clinic visits— Curex’s Virtual Shot Room model delivers the same SCIT program with live video supervision by trained Curex clinical staff for the first injection from each new vial or concentration and restarts after gaps or reactions.
Allergy Drops / Tablets (SLIT)
Daily drops or dissolvable tablets containing hackberry extract, held under the tongue at home. Same desensitization principle, delivered without injections. WHO-recognized as an effective form of allergy immunotherapy since 2001.
- Taken at home — no weekly clinic trips, no needles
- Lower systemic reaction rate than allergy shots
- Curex offers prescription hackberry immunotherapy drops with allergist oversight
The rest of this page goes deep on allergen-specific immunotherapy with shots — protocol, efficacy data, side effects, and cost. If you’d rather skip the clinic and treat hackberry allergy with at-home drops, see how Curex sublingual immunotherapy compares below.
What is Hackberry?
The biology, taxonomy, and clinical fingerprint of Hackberry — the foundation of how SCIT targets it.
Hackberry is a widespread Great Plains and Texas hardwood reclassified from elm family (Ulmaceae) to hemp family (Cannabaceae) by APG IV in 2016 — an important botanical distinction without clinical cross-reactivity to cannabis.
- Scientific name
- Celtis occidentalis
- Family
- Cannabaceae (formerly Ulmaceae)Hemp family (reclassified 2016)
- Type
- Tree pollen — wind-pollinated deciduous hardwood
- Native to
- Eastern and central US to the northern Great Plains
- Allergen proteins
- No formally named IUIS allergen for Celtis occidentalis as of May 2026
- Particle size
- ~25–30 µm, wind-pollinated
- Avoidance difficulty
- Very difficult
How Hackberry Allergy Presents
Symptoms by body system — useful for distinguishing Hackberry sensitivity from overlapping allergies and infections.
Respiratory
- Sneezing and rhinorrhea during the April–May hackberry pollen window across the Great Plains
- Nasal congestion coinciding with spring hackberry pollen release in Texas and Midwest
- Post-nasal drip worsening outdoors in April and May
- Allergic asthma exacerbation during the spring pollen peak in Plains cities
- Cough from inhaled hackberry pollen on windy spring days
Ocular
- Watery, itchy eyes during April–May hackberry pollen season
- Conjunctival injection on high-count Plains spring days
- Contact lens intolerance coinciding with hackberry pollen peak
- Periorbital edema in highly sensitized individuals
Dermal
- Atopic dermatitis flares during spring hackberry pollen season
- Contact urticaria from handling hackberry foliage (rare)
- Facial flushing in heavily sensitized patients during peak exposure
Systemic
- Fatigue and reduced concentration during the April–May hackberry pollen window
- Sleep disruption from nasal congestion coinciding with spring pollen peak
- Generalized malaise in patients co-sensitized to hackberry, oak, and spring grasses
- Headache from sustained spring sinus congestion
Hackberry is the tree we keep prescribing as 'elm' even though the taxonomists moved it next to cannabis a decade ago. Clinically the elm cross-reactivity holds — but if your panel is positive for hackberry alone and negative for elm, the elm mix is not covering you at all.
When & Where Hackberry Peaks
Allergen intensity by month and by state. Useful for timing SCIT start dates and travel planning.
12-Month Intensity
Peak: April–May across the Great Plains and Texas — a spring window coinciding with oak and early grass pollination· ~6–8 weeks of pollen season
US Exposure Map
8 high-intensity statesExposure intensity by state (text version)
- ME:
- Low
- VT:
- Low
- NH:
- Low
- WA:
- Low
- MT:
- Low
- ND:
- Moderate
- MN:
- Moderate
- WI:
- Moderate
- MI:
- Moderate
- NY:
- Low
- MA:
- Low
- OR:
- Low
- ID:
- Low
- WY:
- Low
- SD:
- Moderate
- IA:
- High
- IL:
- High
- IN:
- High
- OH:
- Moderate
- PA:
- Low
- NJ:
- Low
- CT:
- Low
- RI:
- Low
- CA:
- Low
- NV:
- Low
- UT:
- Low
- CO:
- Low
- NE:
- High
- MO:
- High
- KY:
- Moderate
- WV:
- Low
- VA:
- Low
- MD:
- Low
- DE:
- Low
- AZ:
- Low
- NM:
- Low
- KS:
- High
- AR:
- Moderate
- TN:
- Moderate
- NC:
- Low
- SC:
- Low
- OK:
- High
- LA:
- Moderate
- MS:
- Moderate
- AL:
- Moderate
- GA:
- Low
- TX:
- High
- FL:
- Low
- AK:
- Low
- HI:
- Low
What Hackberry Cross-Reacts With
Patients sensitized to one allergen often react to others sharing similar proteins. This map shows the documented molecular overlaps.
Hackberry cross-sensitization follows the legacy Ulmaceae grouping — modest shared epitopes with elms — but no clinically meaningful cross-reactivity with Cannabis sativa or Humulus lupulus (hops) has been documented despite the shared Cannabaceae family assignment.
Is SCIT Right for Your Hackberry Allergy?
Answer five questions to assess whether hackberry allergy shots are indicated for your spring Great Plains rhinitis.
How severe are your spring (April–May) allergy symptoms in the Great Plains or Texas?
The Hackberry SCIT Protocol
Hackberry SCIT uses a non-standardized extract calibrated individually, typically mixed alongside elm extracts in Plains region allergy practices that recognize both as clinically relevant spring aeroallergens.
Starting from the most dilute hackberry extract, the allergist escalates to the maintenance dose over 6–8 months. Build-up ideally completes before the April hackberry pollen onset. With Curex, the first injection from each new vial or concentration is supervised live in the Virtual Shot Room by trained Curex clinical staff, and a prescribed epinephrine auto-injector is confirmed on hand.
Ongoing maintenance injections continue through successive spring hackberry seasons. With Curex these are administered at home, with changes to a new vial or concentration supervised live in the Virtual Shot Room and a prescribed epinephrine auto-injector confirmed on hand. Annual symptom tracking helps assess improvement.
After a successful course, durable symptom relief that extends beyond the injection period is the goal, consistent with broader non-standardized tree SCIT evidence.
Extract Concentration Ladder
You progress through each vial during build-up. Concentration increases ~10x per step.
What the Research Shows for Hackberry SCIT
No randomized controlled trial has been published for hackberry SCIT. Clinical evidence is extrapolated from regional aerobiology data, limited cross-sensitization studies, and the broader non-standardized tree SCIT evidence base.
- Regional clinical significance as Great Plains aeroallergen45%Levetin E. Aerobiology of pollen and pollen antigens. Clin Allergy Immunol. 2004;18:97–121 — regional importance cited
- Estimated benefit from non-standardized tree SCIT (extrapolated framework)48%Cox L et al., J Allergy Clin Immunol 2011;127:S1–S55 — Practice Parameter Third Update
- Plains pollen-integral increase 1990–2018 (climate trend context)21%Anderegg et al., PNAS 2021;118(7):e2013284118
Hackberry SCIT lacks dedicated efficacy evidence. The APG IV Cannabaceae reclassification (2016) and the absence of any IUIS-named allergen make hackberry one of the most under-characterized important US tree aeroallergens. Clinical prescribing follows the AAAAI/ACAAI Practice Parameter for confirmed sensitization with inadequate pharmacotherapy response; separate hackberry testing before prescribing prevents relying on elm-mix cross-protection that may be incomplete.
Ready to skip the surprise bills?
At-home allergy shots (SCIT) are designed by board-certified allergists. See the listed SCIT plan rate in our pricing record and request a quote for eligibility, initiation and total care costs.
- MD-ledBoard-certified allergists
- QuoteTotal care estimate
- 50K+Patients treated
- HSA/FSAEligible
Hackberry SCIT Side Effects
Hackberry SCIT side effects are consistent with non-standardized inhalant tree extract immunotherapy; local reactions are most common and serious systemic events are rare.
Local reactions
4 documented| Reaction | Rate | Severity |
|---|---|---|
Injection-site erythema and swelling Most common; typically resolves within a few hours | Rate 25–50% | Mild |
Injection-site pruritus Localized itching; cold compress provides relief | Rate 20–35% | Mild |
Large local reaction Swelling >5 cm; may require dose adjustment before next visit | Rate 5–10% | Moderate |
Delayed local soreness Induration appearing 4–8 hours post-injection; self-limited | Rate 5–8% | Mild |
Systemic reactions
4 documented| Reaction | Rate | Severity |
|---|---|---|
Rhinitis or conjunctivitis flare Transient nasal or eye symptom exacerbation; resolves spontaneously | Rate 0.5–1% | Mild |
Urticaria Hives beyond injection site; requires clinical evaluation | Rate 0.1–0.3% | Moderate |
Mild bronchospasm Managed in-clinic; baseline asthma control assessment required before each injection | Rate 0.1–0.2% | Moderate |
Anaphylaxis Extremely rare; Curex supervises the first injection from each new vial or concentration live in the Virtual Shot Room with a prescribed epinephrine auto-injector confirmed on hand | Rate <0.01% | Severe |
SCIT carries a real safety record when proper protocols are followed and epinephrine is available. Curex preserves that record at home with a USP <797> serum, a Virtual Shot Room–supervised the first injection from each new vial or concentration, a prescribed epinephrine auto-injector confirmed on hand, and gradual allergist-overseen escalation.
SCIT vs Alternatives for Hackberry
Spring allergy management for hackberry-sensitized patients includes targeted pharmacotherapy, avoidance (limited for a widespread native woodland tree), sublingual immunotherapy, and SCIT.
| Criterion | At-Home SCIT (Curex)Best | SLIT drops/tablets | Avoidance | Medications |
|---|---|---|---|---|
| Effectiveness | Moderate (no RCT) | Comparable (extrapolated) | Very limited outdoors | Good short-term control |
| 5-yr cost | $3,500–$9,000 | Daily drops (varies by pharmacy) | Low | $500–$2,000/yr |
| Duration | 3–5 years | 3–5 years | Ongoing | Lifelong |
| Convenience | At-home self-injection; weekly → monthly | Daily drops at home | Very difficult — native tree | Daily pill/spray |
| Safety | Very safe | Very safe | Excellent | Generally safe |
| Lasting effect | Yes, years post-tx | Yes, years post-tx | No | No — returns off meds |
At-Home SCIT (Curex)Best
SLIT drops/tablets
Avoidance
Medications
For confirmed hackberry sensitization with multi-season spring symptoms, SCIT offers the most durable long-term benefit. Curex now delivers that SCIT as an at-home allergy shot with pricing confirmed in a current program quote: a hackberry serum compounded under USP <797>, with the first injection from each new vial or concentration supervised live in the Virtual Shot Room, a prescribed epinephrine auto-injector confirmed on hand, and allergist-overseen escalation — so patients who cannot manage weekly clinic visits can still pursue Plains spring allergen immunotherapy.
What Hackberry SCIT Actually Costs
Most major US insurers cover hackberry SCIT under standard allergy benefits when prescribed by a board-certified allergist with documented positive sensitization; in Plains states where hackberry is a recognized regional aeroallergen, prior authorization is typically straightforward with a spring allergic rhinitis diagnosis. Curex at-home IgE testing identifies specific hackberry sensitization before allergist consultations, eliminating the need for an initial skin-test visit.
Cost range varies by deductible, co-insurance, and clinic.
Verify these codes with your insurer to confirm coverage.
See the listed Environmental Allergy Shots Plan rate, commercial terms dated 2026-10-12; consultations are included without copay. Confirm availability, eligibility, other included services, testing, any in-person care, insurance responsibility and billing cadence in your written quote before enrolling.
Join the waitlistStop guessing about your hackberry allergy. Get a plan.
Take Curex’s 3-minute allergy quiz. A board-certified allergist will review your symptoms and recommend the right immunotherapy path for you — shots or drops.
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Hackberry SCIT — Frequently Asked
Quick answers to the questions patients ask most before starting treatment.
Hackberry (Celtis occidentalis) was reclassified from Ulmaceae (elm family) to Cannabaceae (hemp/cannabis family) by the Angiosperm Phylogeny Group IV in 2016, based on molecular phylogenetic evidence. This places it in the same family as Cannabis sativa (marijuana), Humulus lupulus (hops), and Celtis other species. However, the practical clinical implication for allergy is minimal — no published study has documented clinically meaningful IgE cross-reactivity between Celtis pollen and Cannabis or Humulus pollen in US allergy patients (Stokes et al., Ann Allergy Asthma Immunol 2018 cannabis allergy review found no Celtis cross-reactivity data). The Cannabaceae family assignment is a botanical classification based on shared evolutionary ancestry, not on shared allergy-relevant proteins.
Not reliably. The elm mix was designed around Ulmus species, which belong to Ulmaceae — a family that no longer includes Celtis. While legacy cross-sensitization between hackberry and elm pollen has been reported in observational allergy panel data, this cross-reactivity is moderate, not complete. A patient who is IgE-positive to hackberry but not to individual elm species may not be adequately covered by a standard elm mix prescription. A board-certified allergist can order species-specific IgE testing to both Celtis occidentalis and individual Ulmus species, then determine whether a separate hackberry extract or a combined approach is more appropriate. The assumption that 'elm mix covers hackberry' should be verified rather than assumed.
Hackberry is an important spring aeroallergen across the Great Plains states (Nebraska, Kansas, Iowa, South Dakota, North Dakota, Missouri), Oklahoma, Texas, and extending through Illinois and Indiana. It is a widespread upland and riparian hardwood in these regions, often growing along creek banks, roadsides, and disturbed edges where wind dispersal is effective. Pollen monitoring stations in Tulsa, Oklahoma City, and Dallas have documented hackberry as a contributor to spring tree-pollen counts in April–May. Beyond the Great Plains, hackberry is present but less clinically prominent in the Eastern US. Patients living in Plains cities with heavy deciduous woodlands should have hackberry included in their spring tree-pollen IgE panel.
Spring allergy medications (antihistamines, nasal corticosteroids, leukotriene antagonists) effectively suppress hackberry pollen symptoms during the April–May season but provide no lasting immune modification — symptoms return each spring at the same or increasing severity as sensitization progresses. Hackberry SCIT aims to retrain the immune system to tolerate the pollen protein, with the goal of durable symptom reduction that persists after completing the 3–5 year course. The trade-off is the clinic visit schedule (weekly for 6–8 months, then monthly) versus the convenience of daily pills. For patients with moderate-to-severe spring symptoms that are inadequately controlled by medications, or for those wishing to avoid long-term daily drug costs, SCIT is a reasonable alternative to consider.
Yes — Plains region allergists typically combine hackberry with other spring tree allergens (elm, oak, maple, ash, poplar) in a multi-allergen vial protocol, rather than prescribing separate injections for each species. The AAAAI/ACAAI Practice Parameter (Cox 2011; Greenhawt 2023) supports multi-allergen mixes for confirmed sensitizations, with concentration adjustments when combining multiple extracts in a single vial. Because hackberry cross-reactivity with elm is moderate rather than complete, your allergist may include both hackberry extract and elm extract in the spring vial at appropriate concentrations. The specific mix design depends on your sensitization panel results and regional exposure pattern.
Hackberry is common throughout the Great Plains, Texas, Oklahoma, Missouri, Illinois, Iowa, and the middle Mississippi Valley, where it grows as a medium-to-large shade tree in upland forests, riparian corridors, and disturbed urban edges. In Texas, it is common along creek drainages and as a yard or street tree. It can be identified by its distinctive warty-corky bark, asymmetrical leaf base, and small black berries (known as 'sugarberries') that birds frequently eat. In cities like Tulsa, Kansas City, and Dallas, hackberry is planted as a street tree for its drought and heat tolerance. The USDA Plants Database documents its distribution across all 48 contiguous states, though it is most abundant in the central and eastern US.
Most hackberry SCIT patients notice meaningful improvement after one or two full spring pollen seasons on the maintenance dose — typically 12–24 months into treatment. The build-up phase (6–8 months of weekly injections) may provide partial benefit during the first hackberry season if timing aligns. Because no randomized controlled trial of hackberry-specific SCIT has been published, these timelines are extrapolated from the broader non-standardized tree SCIT literature (Cox 2011 Practice Parameter). Consistent adherence to the injection schedule is the primary determinant of how quickly and substantially symptoms improve. Keeping a symptom diary across successive spring seasons provides objective evidence of treatment benefit.
Elms (Ulmus) and hackberry (Celtis) belong to different plant families since the APG IV reclassification — elms remain in Ulmaceae while hackberry moved to Cannabaceae. For allergy immunotherapy this matters because SCIT extracts are species-specific: an elm extract made from Ulmus parvifolia or U. americana does not necessarily contain the same IgE-binding proteins as a Celtis occidentalis extract. The legacy cross-sensitization between the two genera is based on shared epitopes discovered before the reclassification, and the cross-reactivity is moderate rather than complete. For prescribing purposes, your allergist should distinguish between elm sensitization (positive Ulmus IgE) and hackberry sensitization (positive Celtis IgE), since a patient positive only for hackberry should receive hackberry extract, not elm mix.
This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about a medical condition. Content reviewed by board-certified allergists at Curex.
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