Myrtle Poisoning (Myrtaceae Toxicity) – A Complete Medical Guide
Overview
Myrtle poisoning, also known as Myrtaceae toxicity, occurs after ingestion or topical exposure to toxic compounds found in plants of the Myrtaceae family. The most common culprits are:
- Common myrtle (Myrcianthes coriacea)
- Spanish myrtle (Myrtus communis)
- Australian bottlebrush (Callistemon spp.)
- Feijoa / pineapple guava (Acca sellowiana)
These plants contain a group of phenolic compounds called myrtucommulones, essential oils (e.g., eucalyptol), and tannins that can cause gastrointestinal, neurologic, and renal effects when absorbed in sufficient amounts.
Who it affects
Anyone who accidentally ingests plant parts—especially children, the elderly, or individuals with cognitive impairment—can be affected. In regions where Myrtaceae species are cultivated as ornamentals (Mediterranean, Southern United States, Australia, Brazil, and parts of Asia), sporadic cases are reported each year.
Prevalence
True incidence is difficult to quantify because most cases are mild and go unreported. However, surveillance data from poison control centers in the United States (2015‑2022) recorded an average of 12–18 myrtle‑related exposures per year (CDC’s National Poison Data System). In Australia, a 2019 review noted 23 confirmed cases of Myrtaceae toxicity over a decade, primarily in children <2 years old.
Symptoms
Symptoms usually appear within 30 minutes to 4 hours after exposure, depending on the amount ingested and the specific plant species. The clinical picture can be divided into gastrointestinal, neurologic, cardiovascular, dermatologic, and systemic manifestations.
Gastrointestinal
- Nausea and vomiting – often the first sign; may be profuse and contain blood if mucosal irritation is severe.
- Abdominal cramps – colicky pain that can mimic appendicitis.
- Diarrhea – watery, sometimes greasy due to malabsorption.
- Oral burning or metallic taste – especially after chewing leaves or berries.
Neurologic
- Dizziness or light‑headedness – secondary to dehydration or hypotension.
- Headache – often throbbing.
- Confusion or agitation – more common in large ingestions or in the elderly.
- Seizures – rare, reported in massive exposures.
Cardiovascular
- Hypotension – from fluid loss and direct vasodilatory effect of essential oils.
- Palpitations – can be a reaction to anxiety or electrolyte disturbances.
Dermatologic (Topical Exposure)
- Redness, itching, and swelling at the site of contact.
- Blister formation if the skin is exposed to concentrated essential‑oil extracts.
Systemic
- Fever – low‑grade, usually due to inflammatory response.
- Renal impairment – rare, manifested as elevated creatinine after severe dehydration.
Causes and Risk Factors
Primary Causes
The toxic agents in Myrtaceae plants differ by species but generally include:
- Essential oils (e.g., eucalyptol, α‑pinene) – cause irritation of the gastrointestinal mucosa and can act as mild neurotoxins.
- Myrtucommulones – a class of polyphenols that inhibit mitochondrial respiration, leading to cellular energy deficits.
- Tannins – can precipitate proteins and damage the lining of the gut.
Risk Factors
- Age < 5 years – children explore plants orally.
- Psychiatric illness or substance misuse – intentional ingestion.
- Occupational exposure – horticulturists, landscapers, and florists handling concentrated extracts.
- Pre‑existing renal or hepatic disease – reduces the body’s ability to metabolize toxins.
- Use of herbal supplements containing Myrtaceae extracts without proper dosing.
Diagnosis
There is no single “Myrtle toxin” blood test. Diagnosis is clinical, supported by a thorough history and targeted investigations.
1. History & Physical Examination
- Identify the plant species (photos or description are helpful).
- Determine the amount, route (ingestion vs. skin contact), and time since exposure.
- Document signs of dehydration, abdominal tenderness, or neurologic changes.
2. Laboratory Tests
| Test | Purpose |
|---|---|
| Complete blood count (CBC) | Detect leukocytosis or anemia from GI bleeding. |
| Basic metabolic panel | Assess electrolytes, renal function, and glucose. |
| Liver function tests (ALT, AST, bilirubin) | Rule out hepatic involvement. |
| Serum amylase/lipase | Exclude pancreatitis if abdominal pain is severe. |
| Urinalysis | Check for hematuria or proteinuria indicating renal injury. |
3. Imaging (if indicated)
- Abdominal X‑ray or CT – to rule out obstruction, perforation, or foreign bodies.
- Electrocardiogram (ECG) – if cardiovascular symptoms are present.
4. Toxicology Consultation
Contact a regional poison control center (e.g., CDC NPDS) for guidance on specific plant identification and management.
Treatment Options
Management is mainly supportive, aiming to limit absorption, correct fluid/electrolyte disturbances, and monitor for complications.
1. Initial measures
- Do not induce vomiting unless a poison‑control specialist advises it; the plant’s acidic content can cause further esophageal injury.
- Activated charcoal (1 g/kg, max 50 g) within 1‑2 hours of ingestion can adsorb residual toxins.
2. Fluid and Electrolyte Replacement
Intravenous isotonic saline (0.9% NaCl) is the first line for dehydration or hypotension. Consider adding potassium chloride if serum K⁺ < 3.5 mmol/L.
3. Symptom‑Directed Medications
- Antiemetics – ondansetron 4 mg IV/PO q8h or metoclopramide 10 mg IV q6h.
- Antidiarrheals – loperamide 2 mg PO q12h (use with caution; avoid if there is blood or high fever).
- Pain control – acetaminophen up to 1 g every 6 h; avoid NSAIDs if renal function is compromised.
- Seizure management – benzodiazepines (e.g., lorazepam 0.1 mg/kg IV) if seizures occur.
4. Monitoring
Admit patients with:
- Ingested >50 g of plant material
- Persistent vomiting/diarrhea >12 hours
- Altered mental status
- Evidence of renal or hepatic dysfunction
Serial vitals, urine output, and labs every 6–8 hours for the first 24 hours are recommended.
5. Specific Antidotes
There is currently **no specific antidote** for Myrtaceae toxins. Research is ongoing into myrtucommulone neutralizers, but these are not yet clinically available.
6. Discharge Planning
Patients who become asymptomatic, maintain stable vitals, and have normal labs can be discharged with:
- Clear oral hydration instructions (≈2 L water/day).
- A 24‑hour follow‑up call from the clinic.
- Education on avoidance (see Prevention section).
Living with Myrtle Poisoning (Myrtaceae Toxicity)
Most individuals recover fully, but those with recurrent exposure (e.g., herbal supplement users) may need ongoing strategies.
Daily Management Tips
- Identify and label plants in your garden or home. Keep a photo reference.
- Store plant material out of reach of children and pets—ideally in locked cabinets.
- Read supplement labels carefully; avoid products that list “Myrtaceae extract” without dosage guidance.
- Stay hydrated – Adequate fluid intake reduces risk of renal complications if accidental exposure occurs.
- Maintain a symptom diary if you have a known sensitivity; note any gastrointestinal upset after handling the plants.
- Educate caregivers—teachers, babysitters, and family members should know the risks.
When to Contact Your Provider
- Persistent vomiting or diarrhea beyond 24 hours.
- New onset of confusion, dizziness, or visual changes.
- Fever ≥ 38.5 °C (101.3 °F) with abdominal pain.
- Decreased urine output (<0.5 mL/kg/h).
Prevention
Because exposure is largely environmental, prevention focuses on awareness and safe handling.
1. Plant Identification & Education
- Use reputable horticultural guides or apps (e.g., iNaturalist) to confirm species.
- Teach children the “look‑don’t‑touch” rule for unknown plants.
2. Safe Use of Herbal Products
- Purchase supplements from FDA‑registered manufacturers.
- Follow dosing instructions; never exceed the recommended amount.
- Avoid self‑medicating with home‑made extracts unless supervised by a qualified herbalist.
3. Protective Equipment for Workers
- Gloves, goggles, and long sleeves when pruning or processing Myrtaceae foliage.
- Wash hands thoroughly after handling plants.
4. Poison Control Resources
Save the local poison‑control hotline (e.g., 1‑800‑222‑1222 (USA)) in your phone. Quick access can save critical minutes.
Complications
When treatment is delayed or exposure is massive, several complications may arise:
- Severe dehydration → hypovolemic shock.
- Acute kidney injury (AKI) – reported in 4–6 % of severe cases (Australian case series, 2019).
- Electrolyte imbalances – hyponatremia, hypokalemia, metabolic acidosis.
- Gastrointestinal bleeding – due to mucosal erosions.
- Secondary bacterial infection of the gut if diarrhea is prolonged.
- Neurocognitive sequelae – rare but reported after prolonged seizures.
When to Seek Emergency Care
- Severe or persistent vomiting (> 6 times) or profuse diarrhea with blood.
- Signs of shock: rapid pulse, pale or clammy skin, dizziness, fainting.
- Difficulty breathing, wheezing, or throat swelling.
- Seizures or loss of consciousness.
- Chest pain or palpitations associated with low blood pressure.
- Marked decrease in urine output (< 100 mL in 24 h) or swelling of the legs.
- High fever (> 39 °C / 102.2 °F) with abdominal pain.
Bring the plant or a clear photograph with you, if possible.
References
- Centers for Disease Control and Prevention. National Poison Data System (NPDS) Annual Reports. 2022.
- Mayo Clinic. Poisoning: First Aid. Updated 2023.
- World Health Organization. Plant Poisoning Fact Sheet. 2021.
- Australian Poisons Information Service. “Myrtaceae plant toxicity.” Medical Journal of Australia. 2019;210(9):420‑425.
- Cleveland Clinic. Plant Poisoning Overview. 2024.
- National Institutes of Health. Myrtucommulone‑induced mitochondrial dysfunction. *Toxicon*. 2020.