Adult patients (18-55 years of age) with clinical diagnosis of acute renal colic (sudden sharp colic flank pain with or without radiation to genitalia or groin and with or without urinary symptoms) who had pain score of 5 or more measured by 10-cm visual analogue scale (VAS), will be included. Will be excluded those who had history of cardiovascular, hepatic, renal or metabolic diseases, patients with evidence of sepsis or clinical suspicion of urinary tract infection, hemodynamically unstable patients (systolic blood pressure <90 mmHg), patients with uncontrolled diabetes, pregnancy, breastfeeding, patients unable to understand verbal and/or written information, patients receiving analgesics within 6 hours before presentation, serum potassium less than 3.7 mmol/l, concomitant use of any beta blockers (including beta-blocker containing eye drops), prolonged-release long-acting β-agonists, use of short-acting β2-agonists within the 6 h preceding presentation to the emergency department, any contraindication to the use of terbutaline, history of drug dependence or chronic consumption of alcohol. Will be also excluded patients with known allergy to paracetamol or terbutaline, patients with abdominal tenderness as a sign of peritoneal inflammation and those with any clinical suspicion for diseases other than urolithiasis, including abdominal aortic aneurysm or dissection.

Inclusion criteria:

• Adults aged 18-65 years
• Clinical diagnosis of acute renal colic (defined as sudden sharp colicky flank pain with or without radiation to the genitalia or groin, and with or without urinary symptoms)
• Pain score of 5 or more measured using the 10-cm NRS scale

Exclusion Criteria:

• History of cardiovascular, hepatic, renal, or metabolic diseases
• Evidence of sepsis or clinical suspicion of urinary tract infection
• Hemodynamically unstable (systolic blood pressure < 90 mmHg)
• Uncontrolled diabetes
• Pregnancy or breastfeeding
• Inability to understand verbal and/or written information
• Received any analgesics within 6 hours prior to presentation
• Serum potassium < 3.7 mmol/L
• Concomitant use of:

Any beta-blockers (including beta-blocker-containing eye drops)

Prolonged-release long-acting β-agonists

Short-acting β2-agonists within 6 hours prior to presentation

• Contraindication to terbutaline use
• Known allergy to paracetamol or terbutaline
• Abdominal tenderness suggestive of peritoneal inflammation
• Clinical suspicion of conditions other than urolithiasis, including:
• Abdominal aortic aneurysm
• Aortic dissection
• History of drug dependence or chronic alcohol consumption