Contrast Reaction Suspected
During or soon after IV iodinated or gadolinium contrast
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RadiologyEmergency
Contrast Reaction Management (ACR Manual 2026)
Contrast Reaction Management (ACR Manual 2026): Contrast Reaction Suspected → Stop Contrast and Call for Help → Anaphylaxis signs? → Anaphylaxis: Give I...
Pathway Overview
17 steps
Algorithm Steps
17 total
01Start 02Warning Stop Contrast and Call for Help
Keep the IV cannula in. Check airway, breathing, circulation.
- Stop the injection; keep the IV cannula in place
- Call for help; bring the emergency trolley; attach SpO2, BP and ECG monitoring
- If in doubt whether it is anaphylaxis, treat as anaphylaxis
03Decision Anaphylaxis signs?
Throat or tongue swelling, stridor, hoarse voice, wheeze or persistent cough, breathing difficulty, low SpO2; young child pale and floppy; or any low BP, persistent dizziness or collapse (adult SBP <90 mmHg or a fall >30%; child: low BP for age) unless it is a slow pulse with pallor and no other signs; or skin signs with severe, persistent abdominal pain or vomiting
- If Yes
04Warning Anaphylaxis: Give IM Adrenaline Now
Do not delay adrenaline. Antihistamines and steroids do not treat airway swelling or shock.
- Adrenaline 1 mg/mL IM, outer mid-thigh: 0.01 mg/kg (0.01 mL/kg), max 0.5 mg (0.5 mL). Adult or >50 kg: 0.5 mg. Or an adrenaline autoinjector
- Lay flat, legs raised; sit with legs out if breathing is hard; do not stand or walk. Pregnant, vomiting or unconscious: on left side
- Call the resuscitation team (code blue or MET); outside hospital call 000
05Action Anaphylaxis: Oxygen, Fluids, Repeat Adrenaline
If no or poor response: repeat IM adrenaline every 5 min
- Oxygen 6-10 L/min by face mask; monitor SpO2, BP, heart rate, ECG
- Low BP: 0.9% sodium chloride 10-20 mL/kg IV rapidly (max 1 L per bolus; adult 1 L); repeat as needed
- Cardiac arrest: start CPR and advanced life support
- Stridor: add nebulised adrenaline 5 mL of 1 mg/mL (5 mg). Wheeze that persists after adrenaline: salbutamol 8-12 puffs of 100 micrograms by spacer, or 5 mg nebulised
- After adrenaline only (optional): hydrocortisone 5 mg/kg IV (max 200 mg). Steroids do not treat the acute reaction
- Skin symptoms after anaphylaxis is treated: oral non-sedating antihistamine. Do not give injectable promethazine
06Warning No Improvement After 2 Adrenaline Doses: Refractory Anaphylaxis
Start an adrenaline infusion. On a beta-blocker: add glucagon 1-2 mg IV over 5 min (adult)
- Call expert help now: ED senior, ICU or anaesthesia; early airway management if airway swelling
- Start IV adrenaline infusion (dedicated line) by local protocol or the ASCIA refractory anaphylaxis flowchart; give IM adrenaline every 5 min until it runs
- IV adrenaline bolus is not recommended; only peri-arrest (adult or school-age child), by an experienced clinician: 1 microgram/kg (max 50 micrograms) over 1-2 min, from 1 mg in 10 mL (100 micrograms/mL). Never give 1 mg/mL IV
07Action Observe After the Reaction
Anaphylaxis: observe at least 4 h after the last adrenaline dose
- Mild skin reaction: observe until symptoms settle; vital signs every 15 min
- Admit overnight: severe or refractory reaction, more than 1 adrenaline dose, IV fluid resuscitation, past severe, refractory or biphasic anaphylaxis, severe asthma, arrhythmia or mastocytosis, lives alone or far from care, late evening
- Do not stand or walk until stable: at least 1 h after 1 adrenaline dose, 4 h after more than 1
- Symptoms can return within 48 h (3-20% of anaphylaxis): tell the patient to call 000
- After anaphylaxis: refer to a clinical immunology or allergy specialist
- Suspected anaphylaxis: take blood for mast cell tryptase as soon as possible after treatment starts, and again 1-2 h (no later than 4 h) after onset
08Action Record the Reaction
Record the exact agent, so a different agent can be chosen next time
- Contrast agent brand name, dose, route and time
- Signs, severity, type (allergic-like or physiologic), treatment and response
- Allergic-like or unknown type: add the exact agent to the allergy or alert list
- Give the patient written details of the reaction and the agent
09Decision Allergic-like or unknown-type reaction?
Physiologic reactions (vasovagal, nausea, high BP) do not need premedication
- If Yes
10Action Allergic-like Reaction: Plan Future Contrast
Prior severe reaction: avoid the same contrast class if possible. If it must be used: premedicate if feasible and have a resuscitation-skilled team present
- Use another test if it answers the question equally well. If contrast is needed: use a different agent of the same class
- Consider premedication (adult): prednisone or prednisolone 50 mg PO at 13 h, 7 h and 1 h before; antihistamine 1 h before is optional
- Urgent (adult, 4-5 h): methylprednisolone 40 mg IV or hydrocortisone 200 mg IV now and every 4 h until contrast
- Child: prednisone 0.5-0.7 mg/kg PO (max 50 mg) at 13 h, 7 h and 1 h before
- Regimens shorter than 4-5 h have no proven benefit; premedication does not prevent all reactions
- Mild delayed skin rash only: premedication is not advised
11Outcome Future Contrast Plan Recorded
Share the plan with the patient and referrer
If No12End Physiologic Reaction: No Premedication Needed
Record the reaction; no change to future contrast is needed
If No13Decision Low BP with slow pulse (<60/min)?
Pale, sweaty, no skin, airway or breathing signs. Slow pulse is age-specific in a child
- If Yes
14Action Vasovagal Reaction: Low BP With Slow Pulse
On a beta-blocker, or any skin, airway or breathing sign: treat as anaphylaxis (IM adrenaline)
- Raise legs at least 60 degrees; oxygen 6-10 L/min by face mask; monitor
- 0.9% sodium chloride IV rapidly: adult 1 L; child 10-20 mL/kg (max 1 L)
- Still symptomatic: atropine IV, adult 0.6-1 mg, repeat to max 3 mg total; child 0.02 mg/kg per dose (min 0.1 mg), max total 1 mg (adolescent max total 2 mg)
- No response: call the resuscitation team and reconsider anaphylaxis
- Path rejoins step 07Shared downstream outcome
If No15Decision Skin, eye or nose signs only?
Hives, itch, flushing, face or lip swelling, sneezing, with normal breathing and BP
- If Yes
16Action Skin or Nose Signs Only: Observe, Oral Antihistamine
Any airway, breathing or BP change: this is anaphylaxis. Give IM adrenaline now
- Limited hives, itch, flushing, sneezing: often no treatment needed
- Widespread or bothersome hives: oral non-sedating antihistamine, e.g. fexofenadine 180 mg PO (adult)
- Face or lip swelling without throat or breathing signs: observe closely
- Keep the IV cannula in; check vital signs every 15 min
- Path rejoins step 07Shared downstream outcome
If No17Action No Allergic Signs: Other Reaction Types
Adult doses. Low BP with a normal or fast pulse, or skin signs with severe vomiting or abdominal pain: treat as anaphylaxis (IM adrenaline). Call the resuscitation team if severe or not settling
- Seizure: protect, lay on side, suction, oxygen; if it continues, benzodiazepine by local protocol
- Low blood glucose: oral glucose 15 g if able to swallow; if not, glucose 25 g IV (50 mL of 50%) or glucagon 1 mg IM
- Pulmonary oedema: sit up; oxygen; furosemide 20-40 mg IV over 2 min
- Hypertensive crisis (DBP >120 or SBP >200 mmHg, or end-organ signs): labetalol 20 mg IV over 2 min; may double every 10 min. Asthma, heart block or slow pulse: no labetalol; give nitroglycerin 0.4 mg SL, repeat every 5-10 min, and furosemide 20-40 mg IV over 2 min. Taking a PDE5 inhibitor (sildenafil, tadalafil, vardenafil) or riociguat: no nitroglycerin; get urgent medical advice
- Nausea, vomiting or anxiety: supportive care; reassure; observe. Anxiety only after other causes are excluded
- Rash from hours to 1 week later: usually self-limiting; blisters, mucosal or systemic signs need urgent review
- Path rejoins step 07Shared downstream outcome
Guideline Source
ACR Manual on Contrast Media (2026 version), Tables 1-3 and Chapter 4
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Doses are for adults unless a child dose is stated; for other child doses see ACR Table 2 or ASCIA
- Premedication reduces but does not prevent reactions; be ready to treat anaphylaxis at the next contrast scan
- Biphasic and delayed reactions can occur after discharge
- Does not cover contrast extravasation, contrast-associated kidney injury or thyroid effects
- Australian contrast guideline (RANZCR v2.3, 2018) is under revision; recheck this pathway when the new version is published
Applicable Regions
USEUAU
AU: Anaphylaxis steps follow ASCIA 2026 (IM adrenaline 0.01 mg/kg, max 0.5 mg; 4 h observation). Diphenhydramine injection is not on the ARTG: use an oral non-sedating antihistamine. Glucagon for beta-blocker patients from RANZCR guideline. Call 000.
US: ACR Table 3 gives IM epinephrine 0.3 mg (adult) and, in hypotension, IV epinephrine 0.1 mg (1 mL of 0.1 mg/mL) slowly; diphenhydramine 25-50 mg PO, IM or IV is available.
Version 2Next review: 2027-09-30
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Frequently Asked Questions
What is the Contrast Reaction Management (ACR Manual 2026)?
The Contrast Reaction Management (ACR Manual 2026) is a emergency clinical algorithm for Radiology. It provides a structured decision tree to guide clinical decision-making, based on ACR Manual on Contrast Media (2026 version), Tables 1-3 and Chapter 4.
What guideline is the Contrast Reaction Management (ACR Manual 2026) based on?
This algorithm is based on ACR Manual on Contrast Media (2026 version), Tables 1-3 and Chapter 4.
What are the limitations of the Contrast Reaction Management (ACR Manual 2026)?
Known limitations include: Doses are for adults unless a child dose is stated; for other child doses see ACR Table 2 or ASCIA; Premedication reduces but does not prevent reactions; be ready to treat anaphylaxis at the next contrast scan; Biphasic and delayed reactions can occur after discharge; Does not cover contrast extravasation, contrast-associated kidney injury or thyroid effects; Australian contrast guideline (RANZCR v2.3, 2018) is under revision; recheck this pathway when the new version is published. Individual patient factors may require deviation from these recommendations.
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