First-Line Pain Management for Renal Colic
NSAIDs are the first-line treatment for acute renal colic, with intramuscular diclofenac 75 mg being the preferred agent and route of administration. 1, 2, 3
Primary Treatment Approach
Administer analgesia within 30 minutes of assessment to provide rapid pain relief. 1
NSAIDs as First-Line Therapy
Intramuscular diclofenac 75 mg is the recommended first-line agent because it provides superior efficacy compared to opioids, reduces the need for additional analgesia, and has fewer side effects. 1, 2, 3
The intramuscular route is preferred because oral and rectal administration are unreliable in acute settings. 1, 3
NSAIDs work by reducing prostaglandin synthesis, which decreases ureteral spasm and inflammation. 2
Alternative NSAIDs include ibuprofen and metamizole, though diclofenac has the strongest evidence base. 3
NSAIDs are significantly more effective than placebo (RR 2.28 for 50% pain reduction within first hour) and more effective than antispasmodics (mean difference -12.97 on VAS). 4
When NSAIDs Are Contraindicated
Use opioids only when NSAIDs cannot be given due to contraindications including: 2, 3
- Renal impairment or renal failure
- Cardiovascular disease
- History of gastrointestinal bleeding
- Pregnancy
- Elderly patients with volume depletion 5
Recommended opioid regimen: Morphine sulfate combined with an antiemetic (cyclizine) given intramuscularly. 1
Avoid pethidine as it has the highest rate of vomiting and need for additional analgesia. 2, 3
In patients with renal impairment, use fentanyl because it does not accumulate active metabolites, unlike morphine, codeine, or tramadol which should be avoided. 2, 3, 6
Opioids cause vomiting in approximately 20% of patients versus 6% with NSAIDs. 7
Critical Monitoring and Failure Criteria
If pain is not controlled within 60 minutes of appropriate analgesia, immediately admit the patient to hospital. 1, 6
Follow-up should occur via telephone one hour after initial assessment and analgesia administration. 1, 6
Complete or acceptable pain control should be maintained for at least six hours. 1, 2
Abrupt recurrence of severe pain warrants immediate hospital admission. 1
Combination Therapy
Adding antispasmodics to NSAIDs does not provide additional benefit and is not recommended. 4
One trial showed that combining morphine with NSAIDs provided greater analgesic effect than either agent alone in only 10% of patients. 7
Scopolamine added to morphine did not provide additional efficacy. 7
Red Flags Requiring Immediate Hospital Admission
Admit immediately if any of the following are present: 1, 6
- Shock or signs of systemic infection/fever
- Failure to respond to analgesia within one hour
- Age over 60 years (consider leaking abdominal aortic aneurysm) 1
- Women with delayed menses (consider ectopic pregnancy) 1, 6
- Sepsis and/or anuria in an obstructed kidney (requires urgent decompression via percutaneous nephrostomy or ureteral stenting) 2, 3
Important Caveats and Pitfalls
NSAID-specific warnings:
NSAIDs may worsen renal function in patients with low glomerular filtration rate, volume depletion, heart failure, or renal artery stenosis—use the lowest effective dose and monitor carefully. 3, 5
NSAIDs increase cardiovascular and gastrointestinal risks, particularly in elderly patients with comorbidities. 3
Never use NSAIDs during pregnancy. 7
In patients on ACE inhibitors, ARBs, or diuretics, NSAIDs can cause acute renal failure—ensure adequate hydration and monitor renal function. 5
Opioid-specific warnings:
Opioids carry risks of addiction, abuse, respiratory depression, and require careful monitoring. 8
Never use standard opioid dosing in renal failure—start with lower doses and titrate carefully. 6
In pregnant women, morphine carries lower risk than NSAIDs. 7
Common pitfalls to avoid: