Histamine Phosphate
Pronunciation: (HISS-tuh-meen FOSS-fayt in-JEK-shun).
- Generic name
- Histamine phosphate
- Brand names
- Histamine Phosphate Injection, Histatrol, Histaprep
- Drug class
- Diagnostics, Procedures & Systems
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What Histamine phosphate is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how Histamine phosphate works
Histamine phosphate acts as an agonist at histamine H1 and H2 receptors. Historically, its H2-receptor activity on gastric parietal cells (stimulating hydrochloric acid secretion) was used in gastric-acid-secretion testing, a use the current FDA label for the marketed product no longer supports. In the skin, it induces vasodilation and increased capillary permeability via H1 receptors, resulting in a wheal-and-flare response, which is the pharmacological basis for its current approved use as an allergy skin-test positive control. (1) (2)
What Histamine phosphate is used for
Positive control in allergy (immediate hypersensitivity/Type I) skin testing — the current FDA-approved use of the marketed product
A small percutaneous or intradermal dose is given alongside allergen skin tests so the clinician can confirm the skin is capable of producing a reaction, making a negative allergen result meaningful. (2)
Historical diagnostic use: assessment of gastric acid secretion (e.g., in achlorhydria/hypochlorhydria) — NOT an approved use of the currently marketed product
CORRECTED: this was a real historical diagnostic practice, largely superseded by pentagastrin testing decades ago. The current FDA label for the marketed histamine phosphate product explicitly prohibits its use for gastric acid secretion testing. Do not treat this as a current approved indication. (2)
Historical diagnostic use: pheochromocytoma diagnosis — NOT an approved use of the currently marketed product
CORRECTED: the current FDA label for the marketed histamine phosphate product explicitly prohibits its use for diagnosing pheochromocytoma, and pheochromocytoma is separately listed as a contraindication (risk of hypertensive crisis). Do not treat this as a current approved indication. (2)
Before taking Histamine phosphate
Do not take / not appropriate for
- Contraindicated in patients with asthma (risk of bronchospasm), active peptic ulcer disease (risk of bleeding), pheochromocytoma (risk of hypertensive crisis), severe cardiovascular disease (risk of arrhythmia or hypotension), and known hypersensitivity to histamine. (Contraindication) (2)
Tell your clinician about
(2)How to take Histamine phosphate
- General Instructions: Histamine phosphate injection is administered by a healthcare professional, usually in a hospital, clinic, or allergy-testing setting. Do not self-administer.. Adult Dosing (CORRECTED to match the current FDA label for the marketed skin-test-control product — an earlier draft of this record contained three different, mutually inconsistent doses for gastric testing and IV use that are not supported by the current label): for percutaneous (prick/puncture/scratch) skin testing, 1 mg/mL histamine base (2.75 mg/mL histamine phosphate); for intradermal skin testing, 0.1 mg/mL histamine base (0.275 mg/mL histamine phosphate). There is no FDA-approved intravenous dose for this product.. Pediatric Dosing: Dosing is determined by the healthcare provider administering the skin test; the clinician-authored record's weight-based gastric-testing dose is a historical figure not applicable to the current approved skin-test use.. Administration: Given by percutaneous or intradermal injection by a trained healthcare provider as part of allergy skin testing.. When To Stop: The injection is given as a single dose for diagnostic purposes as part of a skin-test session. No ongoing therapy is required.. Storage: Store at 2°C to 8°C (36°F to 46°F). Protect from light. Do not freeze.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
As this medication is administered by a healthcare professional as part of a diagnostic skin-test session, missed doses are unlikely. If a dose is missed, consult your healthcare provider for further instructions.
Overdose
Symptoms of overdose may include severe hypotension, shock, bronchospasm, or cardiac arrhythmias. Seek emergency medical attention immediately. Supportive care and symptomatic treatment are essential. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Headache
Incidence: Reported in the clinician-authored database; frequency not established
Flushing
Incidence: Reported in the clinician-authored database; frequency not established
Dizziness
Incidence: Reported in the clinician-authored database; frequency not established
Nausea
Incidence: Reported in the clinician-authored database; frequency not established
Vomiting
Incidence: Reported in the clinician-authored database; frequency not established
Bronchospasm
Incidence: Reported in the clinician-authored database; frequency not established
Hypotension
Incidence: Reported in the clinician-authored database; frequency not established
Tachycardia
Incidence: Reported in the clinician-authored database; frequency not established
Serious warnings
May cause severe allergic reactions, including anaphylaxis — serious
Symptoms: May cause severe allergic reactions, including anaphylaxis. Use with caution in patients with cardiovascular disease. Contraindicated in asthma and peptic ulcer disease. Monitor closely for hypotension and bronchospasm. Not for therapeutic use — diagnostic only.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
CORRECTED FROM FDA LABEL — serious
Symptoms: CORRECTED FROM FDA LABEL: the currently marketed histamine phosphate injection product is explicitly NOT to be used for diagnosis of pheochromocytoma or to test the ability of the gastric mucosa to secrete hydrochloric acid — its only FDA-approved use is as a positive control in allergy skin testing. Small doses may precipitate bronchospasm/asthma symptoms in patients with bronchial hyperreactivity; extreme caution is required in anyone with a history of asthma. The product should not be used in individuals with hypotension, severe hypertension, or severe cardiac, pulmonary, or renal disease.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindications recorded in the clinician database — serious
Symptoms: Contraindications recorded in the clinician database: contraindicated in patients with asthma (risk of bronchospasm), active peptic ulcer disease (risk of bleeding), pheochromocytoma (risk of hypertensive crisis), severe cardiovascular disease (risk of arrhythmia or hypotension), and known hypersensitivity to histamine. Use with caution in elderly patients, those with compromised cardiovascular or respiratory function, and in pregnancy only if clearly needed.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Antihistamines (such as diphenhydramine, loratadine, cetirizine) can block the effects of histamine phosphate injection and should be paused before testing only on the instruction of, and for the duration recommended by, the clinician performing the test. Beta-blockers may increase the risk of severe allergic reactions. Inform your doctor of all medications you are taking. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Requires a primary-source research pass before this section can be completed. Discuss any planned skin testing with the clinician managing the pregnancy. (2)
Breastfeeding
Requires a primary-source research pass before this section can be completed. (2)
Children
Dosing for pediatric skin testing is determined by the healthcare provider administering the test. Frequency: not applicable (single diagnostic dose). Weight-based dosing for the historical gastric-testing use is not applicable to the current approved skin-test use. Age restrictions: safety of the current approved use has not been established by name in the sources reviewed for this record. (2)
Renal_impairment
The FDA label lists severe renal disease as a contraindication (see serious warnings); no graded renal- or hepatic-impairment dose adjustment is established in either source reviewed for this record. (2)
Hepatic_impairment
The FDA label lists severe renal disease as a contraindication (see serious warnings); no graded renal- or hepatic-impairment dose adjustment is established in either source reviewed for this record. (2)
Monitoring
(2)Storage
Store at 2°C to 8°C (36°F to 46°F), refrigerated. Protect from light. Do not freeze.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General (current FDA-approved use — allergy skin-test positive control)
Indication: Positive control in allergy (Type I hypersensitivity) skin testing
Dose summary: CORRECTED — an earlier draft of this record gave "0.5 to 1.0 mg administered intravenously" as the standard adult dose; that figure is not supported by the current FDA label and has been removed. The current FDA-approved dosing for the marketed skin-test-control product is: percutaneous (prick/puncture/scratch) testing, 1 mg/mL histamine base (2.75 mg/mL histamine phosphate); intradermal testing, 0.1 mg/mL histamine base (0.275 mg/mL histamine phosphate). There is no FDA-approved IV dose for this product.
Renal context: Severe renal disease is a contraindication to use (see serious warnings); no graded renal-impairment dose adjustment is established in the sources reviewed for this record. (2)
Historical practice (not the current approved use)
Indication: Gastric acid secretion assessment (achlorhydria/hypochlorhydria) — historical, not currently approved
Dose summary: The clinician-authored database recorded 0.01 mg/kg subcutaneously (not exceeding 0.5 mg) as a historical gastric-testing dose. This use and dose are NOT supported by the current FDA label for the marketed product, which explicitly prohibits use for gastric acid secretion testing. Retained here only as historical/background context, not as a recommended current dose.
Renal context: Not applicable — this is not a current approved use. (1) (2)
Frequently asked questions
What is histamine phosphate injection used for?
The currently marketed product is used as a positive control in allergy skin testing, given alongside allergen tests so a clinician can confirm the skin is capable of reacting. It is not used for gastric acid secretion testing or pheochromocytoma diagnosis — those were historical uses that the current FDA label for this product explicitly does not support.
Can I take histamine phosphate injection at home?
No, this medication should only be administered by a healthcare professional in a clinical setting.
What should I tell my doctor before receiving this injection?
Inform your doctor if you have asthma, heart disease, peptic ulcer disease, severe hypertension, severe renal disease, or are taking antihistamines or beta-blockers.
What are the most common side effects?
Common side effects include redness, swelling, or itching at the injection site, mild headache, or flushing.
What should I do if I experience difficulty breathing after the injection?
Seek emergency medical attention immediately, as this may be a sign of a severe allergic reaction or bronchospasm.
Can antihistamines affect the test results?
Yes, antihistamines can block the effects of histamine and interfere with skin-test interpretation; the clinician performing the test will advise whether and for how long to pause them beforehand.
Is histamine phosphate injection safe for children?
It can be used in children as part of allergy skin testing, but the dose and suitability are determined by the healthcare provider performing the test.
What happens if I take too much Histamine phosphate injection?
An overdose of Histamine phosphate injection can lead to severe symptoms such as profound hypotension, bronchospasm, and cardiovascular collapse. If an overdose is suspected, seek emergency help without delay; prompt intervention is necessary to manage these life-threatening effects and stabilize the patient.
Can I drink alcohol while taking Histamine phosphate injection?
It is generally advisable to avoid alcohol around the time of diagnostic skin testing with histamine phosphate injection. Alcohol can exacerbate some of the side effects associated with histamine agonists, such as flushing and hypotension, potentially complicating the diagnostic assessment and increasing discomfort. Always consult your healthcare provider for personalized advice regarding alcohol intake.
Is Histamine phosphate injection safe during pregnancy?
Pregnancy guidance for histamine phosphate injection is not established in the sources reviewed for this record. The potential risks and benefits to both the mother and the fetus must be evaluated by a healthcare professional. Consult your doctor if you are pregnant, planning to become pregnant, or breastfeeding before receiving this injection.
What is the mechanism of action of Histamine phosphate?
Histamine phosphate acts as an agonist at histamine H1 and H2 receptors. Historically, its H2-receptor activity on gastric parietal cells (stimulating hydrochloric acid secretion) was used in gastric-acid-secretion testing, a use the current FDA label for the marketed product no longer supports. In the skin, it induces vasodilation and increased capillary permeability via H1 receptors, resulting in a wheal-and-flare response, which is the pharmacological basis for its current approved use as an allergy skin-test positive control. (1) (2)
What is the generic name of Histamine Phosphate?
The generic name is Histamine phosphate. It is sold under brand names including Histamine Phosphate Injection, Histatrol, Histaprep.
What class of drug is Histamine phosphate?
Histamine Phosphate is classed as: Diagnostics, Procedures & Systems.
References
- Histamine phosphate injection — MedGuideGlobal medicine recordMedGuideGlobal clinician-authored medicine record · United States · accessed 2026-08-06 · source 1
- HISTAMINE POSITIVE SKIN TEST CONTROL (histamine phosphate injection, solution) — FDA labelU.S. Food and Drug Administration DailyMed · United States · accessed 2026-08-06 · source 2
- ASTHMA THERAPY (ARSENIC TRIOXIDE - HISTAMINE DIHYDROCHLORIDE - DERMATOPHAGOIDES PTERONYSSINUS - MAGNESIUM PHOSPHATE, DIBASIC TRIHYDRATE - STRYCHNOS NUX-VOMICA SEED - ASPIDOSPERMA QUEBRACHO-BLANCO BARK - SUPLHUR -) TABLET, ORALLY DISINTEGRATING [TRP COMPANY] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Histamine Positive Skin Test Control — FDA approval record (Drugs@FDA BLA103754)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
- Histamine phosphate — RxNorm normalized drug concept (RXCUI 142136)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5
Brand names by country
Single-ingredient Histamine phosphate names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Histaminum hydrochloricum200 [kp_C]/200[kp_C], 1 [hp_M]/[hp_M], 30 [hp_C], 6 [hp_C]/6[hp_C], 9 [hp_C]/9[hp_C], 30 [hp_X]/30[hp_X], 30 [hp_X]/30mL, 200 [kp_C] · boiron
- histamine positive skin test control2.75 mg/mL, .275 mg/mL · alk-abello, inc.
- BAKERS BEST Arthritis Pain Relief Cream with Hemp and Lavender.3 mg/g · baker's best health products, inc.
- Histamine Phenolic6 [hp_X]/mL · energique, inc.
- Australian Dream Back Pain.0005 g/g · sombra cosmetics inc.
- Walgreens Arthritis Pain Relief Cream.00025 g/g · walgreens company
- Bakers Best Arthritis Pain Relief.3 mg/g · baker's best health products, llc
- Arthritis Pain Relief Cream.00025 g/g · sombra cosmetics inc.
- 2nd CHANCE MOBILITY Pain Relief.5 mg/g · alpha nutrition, llc
- CVS Arthritis Pain Relief.025 g00g · cvs health
Canada
- HISTATROL