Guaifenesin (GGE): veterinary dose and monograph

At a glance

Drug class

Sedative / anaesthetic

Also known as

GGE, Glyceryl guaiacolate, Guaiphenesin

Species with doses

Dogs, Cattle, Horses, Goats, Sheep and Camelids

General dose range

50–100 mg/kg IV IV to effect (induction) — check the species tables for the indication

Routes

IV, PO

Last reviewed

1 October 2026

Indications

• Muscle relaxation at induction of large-animal anaesthesia
• Component of "triple drip" total intravenous anaesthesia (with ketamine + xylazine) for field surgery
• Improving relaxation/recovery quality in equine and ruminant anaesthesia

Guaifenesin (GGE) dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Muscle relaxation — strychnine / tetanus: Plumb’s p.598 (Morgan 1988; Schmitz 2004): 110 mg/kg IV. Papich 5e: anaesthetic adjunct 2.2 mL/kg/h of 5% with an alpha-2 agonist and ketamine.
• Expectorant (oral): Papich 5e: dogs and cats 3–5 mg/kg q8h PO as an expectorant.

Cattle

• Induction / TIVA component: Plumb’s p.598 (Mandsager 1988): cattle 55–110 mg/kg IV. Use ≤5% to limit haemolysis; titrate. Extra-label — obtain a FARAD withdrawal.

Horses

• Induction muscle relaxation (to effect): Papich 5e: 2.2 mL/kg of 5% (110 mg/kg) IV before ketamine; with propofol, 90 mg/kg over 3 min then propofol 3 mg/kg. Plumb’s p.598: label 110 mg/kg IV — give ⅓–½ until the horse relaxes/falls gently, then the rest; after xylazine sedation usually 30–50 mg/kg by rapid pressurised infusion before ketamine 2.2 mg/kg (Abrahamsen 2007); 25–50 mg/kg to deepen a light field anaesthetic. Use ≤5% solutions (haemolysis). ARCI Class 4.
• Triple drip TIVA (with ketamine + xylazine): Papich 5e: 1 L 5% guaifenesin in dextrose + 500 mg xylazine + 2 g ketamine; 1.1 mL/kg for induction then 2–4 mL/kg/h; yohimbine 0.125 mg/kg speeds recovery. Plumb’s p.598 (Wagner 2009): GKX (guaifenesin 50 mg/mL, ketamine 1–2 mg/mL, xylazine 0.5 mg/mL) at 1.5–2.2 mL/kg/h after xylazine/ketamine induction; GKD alternative with detomidine. Calculate the drip rate — do not overdose.

Goats

• Induction / maintenance (as GKX): Plumb’s p.598: GKX — 1 L of 5% guaifenesin with 1 g ketamine ± up to 100 mg xylazine; induce with 2.2 mL/kg IV (≈110 mg/kg guaifenesin), maintain at about 2.2 mL/kg/h (Wagner 2009); or 500 mL 5% guaifenesin + 50 mg xylazine + 500 mg ketamine at 2–4 mL/kg to recumbency, then slowed (Rings 2005). Calculate carefully — do NOT overdose. Extra-label.

Sheep

• Induction / maintenance (as GKX): Plumb’s p.598: GKX — 1 L of 5% guaifenesin with 1 g ketamine ± up to 100 mg xylazine; induce with 2.2 mL/kg IV (≈110 mg/kg guaifenesin; calculate — do NOT overdose), maintain at about 2.2 mL/kg/h (Wagner 2009); or 500 mL 5% guaifenesin + 50 mg xylazine + 500 mg ketamine at 2–4 mL/kg IV, fast until recumbent then slowed (Rings 2005). Xylazine can cause hypoxaemia/pulmonary oedema in sheep. Extra-label — obtain a FARAD withdrawal.

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• Induction / TIVA component: Plumb’s p.598 (Mandsager 1988): cattle 55–110 mg/kg IV. Use ≤5% to limit haemolysis; titrate. Extra-label — obtain a FARAD withdrawal.

Camelids

• Induction / maintenance (as GKX): Plumb’s p.598 (Wagner 2009): calculate the dose — do NOT overdose.

Contraindications

Use as a sole agent (no anaesthesia/analgesia). Perivascular injection (irritant — thrombophlebitis/tissue necrosis). High concentrations >10 % (haemolysis). Hepatic impairment (prolonged effect). Known hypersensitivity. Always secure the airway and support the anaesthetised patient.

Species-specific warnings

Cattle: Cattle are more sensitive to guaifenesin — use ≤5 % concentration and lower the dose; titrate to effect.

Horses: Ensure IV (perivascular injection is severely irritant) and combine with sedation/analgesia for a safe induction and recovery.

Adverse effects

• Thrombophlebitis / perivascular irritation (especially concentrations >10 %)
• Haemolysis at high concentrations (keep ≤10 %, ideally 5 % in cattle)
• Respiratory depression/apnoea at overdose (relaxes respiratory muscles)
• Hypotension; ataxia/weakness during recovery

Drug interactions

• Ketamine + alpha-2 agonist (xylazine): the classic synergistic "triple drip" TIVA combination
• Other CNS depressants/anaesthetics: additive depression — reduce co-drug doses
• No significant metabolic interactions of note

Pregnancy and lactation

Used in pregnant mares/cattle as part of anaesthesia when required; crosses the placenta with other anaesthetics to depress the neonate at caesarean — minimise and resuscitate.

Monitoring

• Depth of relaxation/anaesthesia (titrate the induction agent after the horse becomes ataxic)
• Respiration (apnoea risk) and oxygenation
• Blood pressure
• IV catheter patency (avoid perivascular injection); recovery quality

Toxicity and overdose

Overdose causes excessive muscle relaxation with apnoea, hypotension and a prolonged, weak, ataxic recovery. High concentrations cause intravascular haemolysis and, if injected perivascularly, severe tissue irritation and necrosis.

Management: No specific antidote. Support ventilation (the relaxant may compromise breathing), maintain circulation with IV fluids/vasopressors, and provide a calm, assisted recovery. For haemolysis, discontinue and support; for perivascular injection, infiltrate the site and treat as an irritant extravasation.

Clinical pearls

• Think large-animal field anaesthesia: guaifenesin is the muscle-relaxant backbone of the "triple drip" with ketamine + xylazine
• Never an anaesthetic by itself — it relaxes muscle but does not abolish awareness or pain
• Keep concentration ≤10 % (≤5 % in cattle) to avoid haemolysis, and warm crystallised solution before use
• Strictly intravenous — perivascular leakage causes nasty tissue necrosis
• Titrate to the point of buckling/ataxia, then induce — don't chase deeper relaxation with guaifenesin alone

Mechanism of action

Centrally acting muscle relaxant that depresses or blocks transmission at internuncial (interneuron) synapses in the spinal cord and brainstem, reducing polysynaptic reflex arcs to produce skeletal-muscle relaxation. It does not act at the neuromuscular junction and has minimal effect on the diaphragm at therapeutic doses; it produces little hypnosis and no analgesia alone.

Formulations and products

• IV solution 50 mg/mL (5 %)
• IV solution 100 mg/mL (10 %)
• Guaifenesin 5 % IV (compounded/vet) (Various) — 50 mg/mL, IV solution
• Guaifenesin (oral expectorant — different use) — Syrup/tablet (expectorant), Oral expectorant (human-label)

Storage

Store 15–30 °C; guaifenesin may crystallise/precipitate when cold — warm gently to redissolve before use and check clarity. Protect from freezing.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other sedatives and anaesthetics

• Detomidine
• Dexmedetomidine
• Diazepam
• Etomidate
• Isoflurane
• Ketamine HCl
• Medetomidine
• Midazolam

Frequently asked questions