Bedside Snapshot

Use It For: Asthma or bronchospasm when inhaled therapy fails; tachysystole with concerning FHR tracing (off-label); short-term preterm-labor tocolysis (off-label). Differs from FDA label: not approved for prolonged tocolysis.
Adult Dose: Bronchospasm: 0.25 mg subcut, repeat once in 15–30 min if needed (max 0.5 mg in 4 hr)
Tachysystole: 0.25 mg subcut, usually once
Pediatric Dose: Under 12 yr (off-label): 0.01 mg/kg subcut, max 0.25 mg/dose, every 20 min for up to 3 doses. 12 yr and older: adult dose. Differs from FDA label: not recommended under 12 yr.
Onset / Duration: Subcut: 5–15 min / 1.5–4 hr (peak 30–60 min)
Do Not Give / Hold If: Tocolysis beyond 48–72 hr, oral or outpatient tocolysis; sympathomimetic allergy; maternal HR >120 bpm; active ischemia or tachyarrhythmia (relative)
Watch For: Tachyarrhythmia (ECG); myocardial ischemia (chest pain, ST change); hypokalemia and hyperglycemia (K⁺, glucose); maternal pulmonary edema (SpO₂, crackles)
Reversal / Rescue: No specific antidote: stop dosing, correct K⁺, supportive care; cardioselective β-blocker only for unstable arrhythmia (can worsen bronchospasm)
Must Remember: US vials are 1 mg/mL: 0.25 mg is 0.25 mL, subcut only. International ampules are 0.5 mg/mL. Anaphylaxis needs IM epinephrine, not terbutaline.

Indications

Emergency & Prehospital

Severe asthma exacerbation: Use it as an add-on when inhaled albuterol is failing or cannot be delivered: minimal air movement, exhaustion, or no way to use a nebulizer. The FDA labels it for age 12 yr and older. In younger children it is off-label.
Reversible bronchospasm in chronic obstructive pulmonary disease (COPD: bronchitis, emphysema): The label covers this use. Inhaled bronchodilators stay first-line.

ED / ICU / Transport

Uterine tachysystole with a concerning fetal heart rate (FHR) tracing: A rapid-acting uterine relaxant. Reach for it when category III or high-risk category II changes persist after oxytocin is paused. Off-label.
Acute intrapartum tocolysis: Buys time for intrauterine resuscitation while the team prepares for an emergency delivery. Off-label.
Preterm labor: Short-term inpatient tocolysis, 48–72 hr at most. The goal is time for antenatal corticosteroids or a maternal transfer. Off-label in the US.
Pediatric status asthmaticus: IV infusion in the pediatric ICU (PICU) when inhaled therapy is failing. Off-label, specialist use only. GINA 2026 does not back routine IV β2-agonist in most severe exacerbations (Evidence A). Save it for selected refractory cases under PICU protocol.

Dosing & Administration

The doses below match the FDA label unless marked. Where the two differ, the page says so.

Available Forms

Injection (US): 1 mg/mL in a 1 mL (1 mg) single-dose vial, labeled for subcut use only. Your usual 0.25 mg dose is 0.25 mL, a quarter of the vial. EMS and labor and delivery (L&D) units carry this form.
Injection (UK and international, Bricanyl): 0.5 mg/mL ampules. That means 0.25 mg is 0.5 mL. Check the concentration on every vial or ampule.
Tablets: 2.5 mg and 5 mg for chronic bronchospasm (12 yr and older). Not used for acute care, and never for tocolysis.
Inhaled: US inhaled products have been discontinued. Outside the US, inhaled terbutaline is still used.

Adult Dosing

Indication	Dose & Route	Repeat / Max	Notes
Bronchospasm (asthma, COPD)	0.25 mg subcut (0.25 mL of 1 mg/mL), lateral deltoid area	Repeat 0.25 mg once in 15–30 min if needed; max 0.5 mg in 4 hr	No response 15–30 min after the second dose: escalate therapy. The 2007 Expert Panel Report 3 (EPR-3) lists 0.25 mg every 20 min for 3 doses, above the US label maximum: use only if your protocol specifies it.
Tachysystole with FHR changes; acute intrapartum tocolysis	0.25 mg subcut	Usually a single dose; repeat only on obstetric order	Give when tachysystole with a concerning tracing persists after oxytocin is paused, alongside repositioning. Expect maternal and fetal tachycardia. Differs from FDA label: the label covers bronchospasm only; the boxed warning says the injection is not approved for prolonged tocolysis (beyond 48–72 hr).
Preterm labor (short-term tocolysis)	0.25 mg subcut	Repeat interval per obstetric protocol; stop within 48–72 hr total (UK labeling: 48 hr); hold if maternal HR >120 bpm	Inpatient only, with continuous maternal and fetal monitoring. Never oral, outpatient or home maintenance (FDA boxed warning).

Pediatric Dosing

Indication	Dose (per kg) & Route	Max Single / Max Total	Notes
Severe asthma, under 12 yr (off-label)	0.01 mg/kg subcut	Max 0.25 mg/dose; every 20 min for up to 3 doses, then every 2–6 hr as needed	Dose on actual body weight. The 0.25 mg cap equals the adult single dose; never exceed it. Differs from FDA label: label does not recommend terbutaline under 12 yr (injection and tablets); UK labeling caps 2–15 yr at 0.3 mg. Three doses in 1 hr can total 0.75 mg in a child of 25 kg or more, above the US label maximum of 0.5 mg in 4 hr for age 12 yr and older: confirm the cumulative limit with protocol or medical direction. Use a 1 mL syringe.
Severe asthma, 12 yr and older	0.25 mg subcut (adult dose)	Repeat once in 15–30 min if needed; max 0.5 mg in 4 hr	FDA-labeled age group.
Status asthmaticus, IV infusion (specialist use)	Weight-based loading dose and continuous infusion per PICU protocol	No fixed max on this page: titrate to effect and tolerance per PICU protocol	GINA 2026: routine IV β2-agonist is not supported in most severe exacerbations (Evidence A); reserve for selected refractory cases. IV beta-agonists have not been shown to be routine first-line in pediatric critical asthma: a 2025 network meta-analysis ranked IV magnesium first and IV beta-agonists second, and called for larger trials. IV beta-agonists ranked highest for preventing intubation, but that rests on one study with zero intubations; IV magnesium ranked best once that study is excluded. In a placebo-controlled trial of 49 children, IV terbutaline added to nebulized albuterol reached no statistically significant outcome; one dysrhythmia and troponin rises in 3 patients (all on terbutaline) were recorded. Dosing per PICU protocol or pediatric formulary. IV adrenergic agonist (ISMP high-alert class): smart pump, dedicated line, continuous ECG, serial K⁺ and troponin. US vials are not labeled for IV use.

Weight-based dose checks: pediatric weight-based dosing.

Preparation & Administration

Syringe: Draw up in a 1 mL (tuberculin) syringe; with 1 mg/mL, 0.25 mg is 0.25 mL. Discard the rest of the vial after single-patient use.
Site: Inject subcut into the lateral deltoid area.
Inspect: Do not use a discolored solution.
Route: US vials are labeled for subcut injection only. They are not for IV infusion. IV use is an off-label PICU practice under institutional protocol.
Reassess before repeating: Work of breathing, SpO₂, air entry and peak flow 15–30 min after each dose; keep inhaled therapy running.

Dosing Notes: Inhaled delivery acts on the airways faster and brings fewer systemic adverse effects. GINA 2026 notes both points. Subcut terbutaline is a bridge for patients who cannot move enough air for aerosol therapy. Renal considerations are under Special Populations.

Contraindications & Precautions

Contraindications

Prolonged tocolysis: injection beyond 48–72 hr, any outpatient or home maintenance tocolysis, and oral terbutaline for any tocolysis
Hypersensitivity: to sympathomimetic amines or any product component
As a tocolytic (UK labeling): gestation <22 weeks; threatened miscarriage in the 1st or 2nd trimester; ischemic heart disease or significant risk factors for it; conditions where prolonging the pregnancy is hazardous (severe preeclampsia or eclampsia, intrauterine infection, bleeding from placenta previa, abruption, cord compression); intrauterine fetal death or a known lethal malformation; pulmonary hypertension, hypertrophic obstructive cardiomyopathy or other left ventricular outflow obstruction (e.g. aortic stenosis). UK labeling also limits tocolytic treatment to 48 hr.

Precautions

Cardiovascular disease: Use caution with coronary insufficiency, arrhythmias or hypertension. β-agonists can cause ST depression, T-wave flattening and QTc prolongation.
Hyperthyroidism, diabetes, seizure disorders: An exaggerated response, hyperglycemia and rare seizures are the risks here.
Hypoxia: Low oxygen raises the risk of hypokalemia and arrhythmia in acute severe asthma.
Labor: It relaxes the uterus. For bronchospasm in labor, use it only when the benefit clearly outweighs the risk.

Hold / Reassess If

Maternal HR >120 bpm during tocolysis
New chest pain, ischemic ST changes or a new tachyarrhythmia
Dyspnea, crackles or falling SpO₂ in a pregnant patient (pulmonary edema)
No improvement 15–30 min after the second adult dose: escalate instead of repeating

FDA Boxed Warning: Do not use the injection for prolonged tocolysis beyond 48–72 hr, or for maintenance tocolysis at home or as an outpatient. It is not approved for either. Reported harms include maternal death, tachycardia, hyperglycemia, hypokalemia, arrhythmias, pulmonary edema, myocardial ischemia, fetal tachycardia and neonatal hypoglycemia. Do not use oral terbutaline for any tocolysis.

Adverse Effects & Toxicity

Common

Nervousness: 17–31% (0.25–0.5 mg doses)
Tremor: 8–38%, dose-related
Palpitations: 8–23%
Drowsiness: 10–12%
Headache: about 8–9%; dizziness: 1–10%
Nausea and vomiting: 1–4%; injection-site pain, sweating, flushing

Serious / Life-Threatening

Effect	Recognition	Management
Tachyarrhythmia	Palpitations, HR up to 200/min, new rhythm on the monitor	Stop further doses, 12-lead ECG, correct K⁺; cardioselective β-blocker only for arrhythmia with hemodynamic compromise
Myocardial ischemia	Chest pain, ST depression, rising troponin	Stop the drug; serial ECG and troponin; treat as acute coronary syndrome per protocol
Hypokalemia	Falling K⁺, U waves, ectopy; worse with diuretics, steroids, hypoxia	Check K⁺; usually transient, replace if low or arrhythmia
Hyperglycemia, lactic acidosis	Rising glucose and lactate, tachypnea despite better air movement	Monitor glucose and lactate; do not read these as asthma failure and stack more β-agonist
Maternal pulmonary edema	Dyspnea, crackles, falling SpO₂ during tocolysis	Stop terbutaline, oxygen, IV loop diuretic, restrict fluids
Hypersensitivity or paradoxical bronchospasm	Worsening wheeze, angioedema, hypotension	Stop; treat as anaphylaxis with IM epinephrine

Overdose & Toxicity Management

Signs: Excess β-stimulation looks like this: tachycardia, arrhythmia, angina, hypertension or hypotension, tremor, seizures, hypokalemia, hyperglycemia, lactic acidosis.
Immediate management: stop terbutaline; continuous ECG; check K⁺, glucose and a blood gas with lactate; correct metabolic changes; give IV fluid if vasodilation drops the blood pressure (cautiously in pregnancy: pulmonary edema risk); treat seizures per protocol.
Antidote: No specific antidote exists. A cardioselective β-blocker (e.g. metoprolol) may be considered for arrhythmia that causes hemodynamic deterioration. It can trigger bronchospasm. Use extreme caution in asthma.
Extracorporeal removal: The label says there is not enough evidence that dialysis helps.

Monitoring

Parameter	When / How Often	Target / Act If
Clinical: HR and rhythm	Continuous ECG through the 30–60 min peak after each dose	New arrhythmia, chest pain or ST change: stop dosing, 12-lead ECG
Clinical: work of breathing, SpO₂, peak flow	Before and 15–30 min after each dose	No improvement after the second adult dose: escalate (IV magnesium, noninvasive ventilation, airway plan)
Clinical: blood pressure	Every 5–15 min during acute treatment	Low diastolic pressure from vasodilation: fluid bolus (small, cautious boluses in pregnancy or during tocolysis: pulmonary edema risk); reassess hypertension
Laboratory: potassium	Baseline and after repeated doses, especially with other β-agonists, diuretics or steroids	K⁺ <3.5 mmol/L with ectopy, or <3.0 mmol/L: replace and recheck
Laboratory: glucose	Baseline in diabetes; repeat after repeated doses or infusion	Rising glucose: treat per protocol; check ketones in diabetes
Laboratory: lactate, troponin	Persistent tachypnea, chest pain, ST change, any IV infusion	Rising lactate with better airflow suggests β-agonist effect; rising troponin: stop, involve cardiology
Obstetric: maternal HR	Before each dose and continuously during tocolysis	>120 bpm: hold the next dose, notify obstetrics
Obstetric: FHR and contractions	Continuous	Fetal tachycardia is expected; category III tracing that does not resolve: expedited delivery
Obstetric: lungs, SpO₂, fluid balance	Throughout tocolysis, especially with corticosteroids	Crackles or falling SpO₂: stop terbutaline, treat pulmonary edema
Neonate: glucose	After birth when the mother received terbutaline near delivery	Hypoglycemia: treat per neonatal protocol

Interactions & Compatibility

Clinically Significant Interactions

Drug / Class	Effect	What To Do
Other sympathomimetics (epinephrine, high-dose albuterol)	Additive tachycardia and arrhythmia	Label advises against routine co-use; if combined in life-threatening asthma, continuous ECG and K⁺
MAOIs, tricyclic antidepressants (including within 2 weeks of stopping)	Potentiated vascular effects	Give only with extreme caution
β-blockers (especially nonselective, including eye drops)	Block bronchodilation; may cause severe bronchospasm	Avoid in asthma; cardioselective agent only if essential
Loop and thiazide diuretics	Worse hypokalemia and ECG changes	Monitor K⁺ and ECG
Corticosteroids (methylprednisolone, betamethasone)	Hypokalemia, hyperglycemia; pulmonary edema reported with co-use in preterm labor	Monitor K⁺, glucose, lungs and fluid balance
Methylxanthines (aminophylline, theophylline)	Arrhythmia and sudden death in animal studies; additive hypokalemia	Continuous ECG; monitor K⁺
Halogenated anesthetics	Ventricular arrhythmias; uterine atony and bleeding at cesarean	Tell anesthesia the time of the last dose; avoid halothane
Insulin and other antidiabetics	Glucose rise blunts their effect	Monitor glucose; adjust therapy

IV Compatibility

US product: Labeled for subcut injection only. No IV dilution is labeled.
Off-label IV infusion: UK labeling dilutes it in D5W, saline or dextrose-saline for bronchospasm. In pregnancy, use D5W only, because saline raises the risk of pulmonary edema.
Incompatible: alkaline solutions (pH >7).
Verify with an institutional compatibility resource.

Special Populations

Pediatrics: Not FDA-labeled under 12 yr, because the data are insufficient. Weight-based subcut dosing is widely used off-label for severe asthma in children who cannot use inhaled therapy or are not responding to it. See the Pediatric Dosing table.
Neonates: Not used to treat neonates. Maternal doses near delivery can cause fetal tachycardia and neonatal hypoglycemia. Tell the neonatal team.
Pregnancy: It crosses the placenta. Cord levels run 11–48% of maternal levels. Rat and rabbit embryofetal studies showed no teratogenic effects. Rat offspring exposed late in pregnancy and during lactation did show changes in behavior and brain development (US label). That is one more reason to keep tocolytic exposure short. Treat acute asthma aggressively. Uncontrolled asthma and fetal hypoxia carry more risk than bronchodilators do. Tocolytic use is inpatient only and limited to 48–72 hr (boxed warning).
Lactation: It passes into breast milk. Infant effects are unlikely at therapeutic doses (UK labeling). The US label lists excretion as unknown. Do not withhold emergency treatment.
Older Adults: Start at the low end. Cardiac disease, arrhythmia and interacting drugs are more common in this group.
Renal Impairment: No labeled adjustment exists for single subcut doses. About 60% leaves the body unchanged in urine, so effects may last longer. Avoid routine repeats and monitor HR and K⁺.
Hepatic Impairment: No specific adjustment is established. Elimination is mainly renal, after sulfate conjugation.
Obesity / Dosing Weight: The adult dose is fixed. It is not weight-based. Pediatric doses use actual body weight and stop at the 0.25 mg cap.

Field & Transport Considerations

Scope: Paramedic, RN and critical-care transport. Some EMS asthma protocols carry subcut terbutaline. It varies by state and agency protocol.
Storage & Stability: 20–25°C (68–77°F); keep vials in the carton to protect from light; discard a discolored solution. Limit heat exposure in vehicles.
Carried Concentration: US vials are 1 mg/mL, so 0.25 mg is 0.25 mL. Read the label aloud. ISMP lists Brethine and Methergine (methylergonovine) as a confused pair. They have opposite effects on the uterus.
Obstetric Interfacility Transport: Confirm the indication, the time and total of every dose, maternal HR, lung sounds, SpO₂, fluid totals and FHR status. Corticosteroids add to the risk of pulmonary edema and hypokalemia.
Infusions in Transport: PICU terbutaline infusions run on a smart pump, through a dedicated line, with continuous ECG. Verify the concentration and mcg/kg/min rate at handoff. Carry enough volume for the trip.
Altitude / Environment: Hypoxia raises the risk of hypokalemia and arrhythmia. Keep oxygenation on target and the monitor on.
Handoff Essentials: time and total dose (mg), response (SpO₂, work of breathing, peak flow), HR trend, K⁺ and glucose if known, and other drugs given (albuterol, ipratropium, magnesium, steroids).

Clinical Pearls

Anaphylaxis is not a terbutaline indication: Wheeze with anaphylaxis gets IM epinephrine first. Inhaled bronchodilators come after that. Terbutaline has no α-effect, so it cannot reverse hypotension or airway edema.

Inhaled first, subcut second: Systemic β-agonists bring more systemic side effects than aerosol therapy does. Aerosol also acts faster. GINA 2026 notes both points. Save subcut terbutaline for the patient too tight or too exhausted to inhale. Keep nebulized therapy running.

β-agonist toxicity mimics worsening asthma: Tachycardia, hypokalemia, lactic acidosis and hyperventilation can follow high doses. Mistake them for asthma failure and you will stack on even more β-agonist.

Exam discriminator: terbutaline vs methylergonovine: Terbutaline relaxes the uterus. It is used for tachysystole and preterm labor. Methylergonovine does the opposite, contracting it for postpartum hemorrhage. It must not be given before delivery. ISMP flags the pair as a confused-name risk.

Tachysystole sequence: Pause oxytocin and reposition the patient. Still tachysystolic with a concerning tracing after oxytocin is paused? Give a rapid-acting uterine relaxant such as terbutaline. A category III tracing that does not resolve calls for expedited delivery.

Selective is not cardio-free: 10–50% of human cardiac β receptors are β2. Even so, controlled studies of subcut terbutaline showed no clear β2 preference. Expect tachycardia and palpitations similar to subcut epinephrine.

Pharmacology

Mechanism of Action

β2-receptor agonist → adenylyl cyclase → more cAMP → bronchial smooth-muscle relaxation and less mast-cell mediator release.
Uterine β2 stimulation → myometrial relaxation (tocolysis).
Skeletal-muscle Na⁺/K⁺ pump stimulation → K⁺ shifts into cells (hypokalemia) and tremor.
Cardiac β2 receptors plus reflex response to vasodilation → tachycardia and palpitations.

Pharmacokinetics

Route	Onset	Peak	Duration
Subcut	5–15 min	30–60 min	1.5–4 hr
PO	30 min (clinical effect 60–120 min)	2–3 hr	4–8 hr

Half-life: about 3–6 hr after subcut dosing (2.9 hr in most patients; mean terminal half-life 5.7 hr in healthy adults); 6–14 hr in some patients. UK labeling reports a longer terminal phase (16–20 hr) after single and multiple dosing.
Metabolism: sulfate conjugation (main metabolite), some glucuronide.
Elimination: about 90% in urine by 96 hr, roughly 60% of it unchanged.
Placental transfer: cord blood levels 11–48% of maternal levels.

Names & Classification

Generic Name: Terbutaline sulfate
Brand Names: Brethine (US; injection discontinued, generic injection and tablets available); Bricanyl (international; discontinued in the US)
Pharmacologic Class: Selective β2-adrenergic agonist
Therapeutic Class: Bronchodilator; tocolytic (off-label)
Controlled Substance: Not controlled
ISMP High-Alert: No for subcut use; IV infusions fall in the ISMP class of IV adrenergic agonists
Look-Alike / Sound-Alike: Brethine / Methergine (methylergonovine); terbutaline / terbinafine

References

Hikma Pharmaceuticals USA. (2021). Terbutaline sulfate injection, USP, 1 mg/mL [prescribing information] (label revised February 2021; DailyMed version posted January 2024). DailyMed, National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=613df3cb-4d55-4d12-ab08-a932481aaa0b
Upsher-Smith Laboratories. (2025). Terbutaline sulfate tablets [prescribing information]. DailyMed, National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3a4e5046-293c-4616-8679-6da65f31626b
AstraZeneca UK. (2022). Bricanyl Injection 0.5 mg/mL: summary of product characteristics. Electronic Medicines Compendium. https://www.medicines.org.uk/emc/product/867/smpc
Global Initiative for Asthma. (2026). Global strategy for asthma management and prevention, 2026 update. https://ginasthma.org/2026-gina-strategy-report/
National Asthma Education and Prevention Program. (2007). Expert Panel Report 3: Guidelines for the diagnosis and management of asthma (landmark guideline; source of the pediatric subcut dose). National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/sites/default/files/media/docs/EPR-3_Asthma_Full_Report_2007.pdf
American College of Obstetricians and Gynecologists. (2025). Intrapartum fetal heart rate monitoring: interpretation and management. Clinical Practice Guideline No. 10. Obstetrics & Gynecology, 146(4), 583–599. https://doi.org/10.1097/AOG.0000000000006049
Xodo, S., de Heus, R., Berghella, V., & Londero, A. P. (2022). Acute tocolysis for intrapartum nonreassuring fetal status: how often does it prevent cesarean delivery? A systematic review and meta-analysis of randomized controlled trials. American Journal of Obstetrics & Gynecology MFM, 4(5), 100639. https://doi.org/10.1016/j.ajogmf.2022.100639
Zakaria, Z. A., Mohd Yusof, A. S., Abas, S., & Manavallan, G. (2023). Terbutaline for acute tocolysis prior to emergency caesarean delivery for suspected foetal compromise. Medical Journal of Malaysia, 78(1), 92–96. https://www.e-mjm.org/2023/v78n1/terbutaline.pdf
Institute for Safe Medication Practices. (2024). ISMP List of Confused Drug Names (updated through June 2024; lists Brethine with Methergine, and terbutaline with terbinafine). https://online.ecri.org/hubfs/ISMP/Resources/ISMP_ConfusedDrugNames.pdf
American College of Obstetricians and Gynecologists. (2016). Practice Bulletin No. 171: Management of preterm labor. Obstetrics & Gynecology, 128(4), e155–e164. https://doi.org/10.1097/AOG.0000000000001711
Bogie, A. L., Towne, D., Luckett, P. M., Abramo, T. J., & Wiebe, R. A. (2007). Comparison of intravenous terbutaline versus normal saline in pediatric patients on continuous high-dose nebulized albuterol for status asthmaticus. Pediatric Emergency Care, 23(6), 355–361. https://doi.org/10.1097/01.pec.0000278397.63246.33
Abu-Sultaneh, S., et al. (2025). Intravenous bronchodilators in pediatric critical asthma: a systematic review and network meta-analysis. Pediatric Pulmonology, 60(7), e71192. https://doi.org/10.1002/ppul.71192

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