Nursing care
SLUDGE mnemonic vs 'hot as a hare': cholinergic and anticholinergic toxicity
Written and reviewed by Nicole Ramirez, BSN, RN, CMSRN · 4 min read · Updated November 2026
Short answer
SLUDGE stands for salivation, lacrimation, urination, defecation, GI upset and emesis, the wet signs of cholinergic excess seen in organophosphate insecticide poisoning. Anticholinergic toxicity is the mirror image: hot as a hare, red as a beet, dry as a bone, blind as a bat, mad as a hatter and full as a flask. Wet points to SLUDGE; dry points away.
What each letter stands for
S is salivation, often drooling. L is lacrimation, meaning tearing. U is urination, sometimes incontinence. D is defecation or diarrhea. G is gastrointestinal upset, mainly cramping. E is emesis. All six come from too much acetylcholine at muscarinic receptors, which is what happens when organophosphate or carbamate insecticides block the enzyme that breaks acetylcholine down.
The anticholinergic rhyme runs the other way. Hot as a hare is fever, red as a beet is flushed skin, dry as a bone is dry mouth, dry eyes and reduced sweating, blind as a bat is dilated pupils, mad as a hatter is agitated delirium with hallucinations, and full as a flask is urinary retention. Some books add extra lines, but these six are the standard set.
When nurses actually use these mnemonics
SLUDGE matters when a client arrives after crop spraying, a suicide attempt with insecticide, or a chemical exposure at work. The nurse uses it to recognize the pattern quickly, then protects staff: clothing comes off, the skin is flushed, and caregivers avoid contaminating themselves while giving care.
The anticholinergic rhyme is used far more often on ordinary wards. Diphenhydramine, tricyclic antidepressants, antiparkinsonian drugs and some antiemetics can all produce it, especially in older adults or after an overdose. A hot, flushed, confused client with a full bladder and no sweat on the skin should make the nurse check the medication list.
Worked scenario: wet client or dry client
Hypothetical scenario, not a real exam item: a farm worker is brought in after spraying a field. He is drooling, wheezing with copious frothy secretions, has diarrhea, small pupils and a heart rate of 44. Options: prepare to give physostigmine, apply a cooling blanket, suction and support breathing while preparing atropine as ordered, or wait for the pupils to dilate before acting.
Supporting breathing and preparing atropine is the best choice, because airway secretions and bronchospasm are the immediate threat. Physostigmine is the tempting distractor: it raises acetylcholine, which treats anticholinergic toxicity but would worsen this client. The cooling blanket fits the dry, hot picture, not this wet one, and pupil size is not the target for atropine.
Where SLUDGE misleads
SLUDGE lists the messy signs and leaves out the dangerous ones. MSD Manuals lists bronchorrhea, wheezing and bradycardia among the muscarinic effects, and the respiratory findings can cause severe hypoxia. Ask about breathing and heart rate even though no letter prompts them.
Pupils are less reliable than students expect. Miosis is the classic muscarinic sign, yet nicotinic effects can produce dilated pupils and a fast heart rate, along with muscle twitching and weakness. Skin and secretions are steadier clues. Atropine is titrated until bronchospasm and bronchorrhea are relieved, and pralidoxime is given after atropine for the neuromuscular weakness.
The exam trap: swapping the antidotes
The classic trap pairs the wrong antidote with the toxidrome. Atropine blocks muscarinic receptors, so it treats the wet cholinergic client and would make an anticholinergic overdose worse. Physostigmine boosts acetylcholine, so it belongs, if at all, to the dry client, and the Royal Children's Hospital guideline notes its use is controversial and should be discussed with toxicology.
For the anticholinergic client, expected nursing care is supportive: airway, breathing and circulation, benzodiazepines as ordered for agitation or seizures, cooling for high temperature, and a bladder scan to decide whether a catheter is needed. If an answer offers atropine to a hot, dry, delirious client, it is almost certainly the wrong one.
Sources and further reading
MSD Manual Professional Edition: Organophosphate Poisoning and Carbamate Poisoning. Muscarinic and nicotinic signs, bronchorrhea, wheezing, bradycardia and hypoxia, atropine titrated to relieve bronchospasm and bronchorrhea, pralidoxime after atropine, decontamination and caregiver protection.
Royal Children's Hospital Melbourne Clinical Practice Guideline: Anticholinergic syndrome. Anticholinergic signs and the hot as a hare mnemonic, common drug causes, benzodiazepines, cooling, bladder scan for retention, and physostigmine use being controversial.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our pharmacology practice questions are the closest set to what this page covers.
One question from the pharmacology set
A client with heart failure is started on furosemide 40 mg PO daily. Which findings should the nurse report to the provider before administering the next dose? Select all that apply.
Rationale
Furosemide is a loop diuretic, so the two things you are watching are potassium and kidney function. A potassium of 2.9 mEq/L is below the 3.5–5.0 reference range and puts the client at risk for dysrhythmia — hold and report. Muscle cramps with palpitations are the clinical face of that same hypokalemia, so they are reported together, not separately. A creatinine that doubles signals the diuresis has outrun renal perfusion. A blood pressure of 132/78 and a 1 kg loss are the expected response to the drug working, not reasons to hold it.
Answer: A, D, E
Common questions
What does SLUDGE stand for?
Salivation, lacrimation, urination, defecation, gastrointestinal upset and emesis. These are muscarinic signs of cholinergic excess, typically from organophosphate or carbamate insecticides. Watch for the signs it leaves out: bronchorrhea, wheezing and bradycardia.
What is the anticholinergic mnemonic?
Hot as a hare (fever), red as a beet (flushed skin), dry as a bone (dry mouth and reduced sweating), blind as a bat (dilated pupils), mad as a hatter (delirium) and full as a flask (urinary retention).
What is the difference between cholinergic and anticholinergic toxicity?
Cholinergic toxicity is wet: secretions, tearing, sweating, diarrhea and often a slow heart rate, treated with atropine. Anticholinergic toxicity is dry and hot: flushed dry skin, fever, dilated pupils, fast heart rate, delirium and urinary retention, managed mainly with supportive care.
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