Acute onset, full-body rash


• Scene – IV 18g, 25mg IV Benadryl
• En route – 2 LPM oxygen nasal cannula


• Response to treatment – Benadryl seemed to improve severity of rash slightly upon arrival at hospital.
• Hospital disposition – unknown.


• Merlin Curry, MD Paramedic University of Arizona
• Elliot Williams, Paramedic Woodburn Ambulance
• David Jones, MD Associate Professor Oregon Health and Science University
• Nathan Peters, Paramedic Woodburn Ambulance


• David M. Spiro, MD, MPH Professor of Pediatrics University of Arkansas Medical Center
• Craig Warden, MD Professor Oregon Health & Science University

• Urticaria (hives)
• Drug rash
• Dementia

Differential Diagnosis

• Critical possibilities
• Anaphylaxis/allergic reaction
• Drug reaction
• Cellulitis
• Vasculitis
• Erythema Migrans/Stevens-Johnson syndrome/Toxic epidermal necrolysis
• Warfarin rash
• Less critical possibilities
• Viral syndrome
• Urticaria Working diagnosis
• Hives, potentially due to medication allergy (cephalosporin)

Patient Workup

• Whole body, itchy hives started ~2 hrs PTA.
• Patient’s dementia and difficulty hearing impaired ability to perform medical history and interviews.

Physical Exam

• Full-body raised hives and rash. No other trauma. No change in airway or breathing.
• GCS – 4/4/6
• CBG – 143

Editor’s Notes

Always ask about new medications or changes in medication dose when taking a history around new-onset rash. Drug rashes can appear in various sizes and locations of the body. Urticaria in particular has a large differential diagnosis including medications, infectious etiologies (viral, bacterial) or allergic response (foods, environmental allergens).
Some EMS systems allow the use of steroids for reactions such as this. Locally we use 0.6 mg/kg of dexamethasone up to 10 mg PO/IM/IV; other places use solumedrol 2 mg/kg up to 125 mg IV or IM. -David Spiro, MD

Standard Approach
Suggested Approach

• Treat these patients like they have a potential life threatening illness, because they do.
• Establish IV access
• Prepare IM epinephrine (1:1000) in case it is needed urgently.
• Give IV fluids along with epinephrine early on in case hypotension develops.
• In less severe cases, can give diphenhydramine; but if the patient has anaphylaxis with any concerning features, always give epinephrine.
• These patients can have a delayed reaction, and should be observed at the hospital. Strongly suggest that anyone with a possible allergic reaction should be transported, even if they are feeling well right now.


• Anaphylaxis is a severe immune response to an allergen (substance causing an allergic response) resulting in a massive histamine release. Symptoms include hypotension (due to vasodilation), vomiting, diarrhea, headaches, rash, edema, wheezing, itching, abdominal pain.
• Anaphylaxis is a life threatening illness. It should be considered whenever someone has wheezing, rash, vomiting, hypotension, edema, altered mental status or headache.
• Epinephrine is the drug of choice for treating anaphylaxis. There have been documented cases of epinephrine administration causing heart attacks, especially in older patients. However, in the setting of severe anaphylaxis with concerning features such as hypotension, airway swelling, difficulty breathing with wheezing, or nausea and vomiting, there is no contraindication to administration of epinephrine.
• Some studies have shown low rates of epi administration even when clear indications are present. Paramedics should have a low threshold for giving epi when the criteria for anaphylaxis are present.
• Epinephrine should be given either by the subcutaneous or intramuscular route using the 1:1000 concentration in a dose of 0.3-0.5mg, and may repeat if necessary. Consider giving epinephrine 1:10,000 concentration IV route if the patient is hypotensive or has airway compromise. As always, follow your local protocol.
• Remember, epinephrine 1:1000 is IM or SC only and should never be given by any other route.
• This case is a classic example of urticaria, likely caused by a medication allergy. It does not meet the criteria for anaphylaxis so there is no need to administer epinephrine at this time. However, his symptoms could progress and quickly establishing an IV and being ready to give epi and fluids is a good idea.
• Cephalosporins are a type of antibiotic that has been known to cross-react with penicillin allergies. If someone looks like they are having an anaphylactic reaction and is known to be allergic to penicillin, check to see if they recently started a cephalosporin.
• For mild allergic reactions (normal blood pressure, no difficulty breathing, no oral swelling), diphenhydramine (Benadryl) is considered a first-line therapy. The allergic reaction happens because of histamine release in the body, and diphenhydramine is an antihistamine.
• Histamine has 2 types of receptors. Diphenhydramine blocks both receptors. Ranitidine is an example of an H2 blocker, a drug that only blocks the H2 receptor. Sometimes people will use both ranitidine and diphenhydramine to really block histamine receptors and treat anaphylaxis
• If you are concerned that someone is having an anaphylactic reaction, you should get an IV in them and give IV fluids.
• Hives are red blotches on the skin. They migrate, meaning they appear and disappear in different places. Hives are potential signs of an allergic reaction.
• When a patient has a history of dementia, note if the family is coming to the hospital, and if not, get a phone number where they can be reached to provide further history to the hospital team.

Suggested references

• Delirium, Dementia, and Amnesia in Emergency Medicine Treatment & Management


• Gender: Male
• Age: 93 years
• Height: Not Available


• Temperature: Not Available
• Blood Pressure: 103/86
• Heart Rate: 85
• Respiratory Rate: 16
• Pulse Oximetry: 96% RA
Signs and Symptoms
Itchy, whole-body rash


• PMH: COPD; dementia; tooth surgically removed 2 days ago, started on cephalexin.
• Allergies: PCN
• Dispatch info: Allergic reaction
• Lives in assisted facility with wife.


• Cephalexin started 6d ago, PerioRx mouth rinse started yesterday.
• Other meds unknown

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