What medications can be used to help pass a small to medium-sized kidney stone in a patient?

Medications to Help Pass a Kidney Stone

For uncomplicated ureteral stones ≤10 mm, alpha-blockers (such as tamsulosin, doxazosin, or terazosin) should be offered as medical expulsive therapy (MET), particularly for distal stones >5 mm, as they increase stone passage rates by approximately 29% compared to observation alone. 1, 2

Pain Management: First Priority

NSAIDs as First-Line

• NSAIDs (diclofenac, ibuprofen, or metamizole) are the primary analgesics for renal colic and should be initiated immediately at the lowest effective dose. 1, 2
• These agents reduce the need for additional analgesia compared to opioids and are more effective than antispasmodics. 2
• Use caution in patients with low glomerular filtration rate, as NSAIDs may impact renal function. 1, 2
• Monitor for cardiovascular and gastrointestinal risks with prolonged use. 1, 2

Opioids as Second-Line

• If NSAIDs are contraindicated or insufficient, use opioids such as hydromorphone, pentazocine, or tramadol—avoid pethidine due to higher vomiting rates and need for additional analgesia. 1, 2

Medical Expulsive Therapy (MET): Facilitating Stone Passage

Alpha-Blockers: The Evidence

• Alpha-blockers demonstrate superior stone-free rates (77.3%) compared to placebo or no treatment (54.4%) for distal ureteral stones <10 mm. 1
• The greatest benefit occurs with stones >5 mm in the distal ureter. 1, 2
• These medications work by relaxing ureteral smooth muscle through alpha-1 receptor blockade. 3, 4
• MET can decrease colic events, narcotic use, hospital visits, and may prevent unnecessary surgeries. 4

Practical Implementation

• Counsel patients that alpha-blockers are used "off-label" for this indication and discuss potential side effects including dizziness, headache, and orthostatic hypotension. 2, 3
• The maximum duration for a trial of MET should be limited to six weeks to avoid irreversible kidney damage. 3
• Patients must have well-controlled pain, no clinical evidence of sepsis, and adequate renal functional reserve to be candidates for MET. 2
• Follow with periodic imaging to monitor stone position and assess for hydronephrosis. 2, 3

Stone-Specific Medical Therapy (For Prevention/Dissolution)

Uric Acid Stones

• Offer potassium citrate to raise urinary pH to 6.0-7.2, which can dissolve existing stones through alkalinization. 1
• Do not routinely offer allopurinol as first-line therapy, as most patients have low urinary pH rather than hyperuricosuria as the predominant problem. 1

Cystine Stones

• Potassium citrate should be used to raise urinary pH to 7.0. 1
• If unresponsive to dietary modifications and alkalinization, offer cystine-binding thiol drugs such as tiopronin (preferred over d-penicillamine due to fewer adverse events). 1

Critical Red Flags Requiring Urgent Intervention

Do not attempt MET in the following situations—these require immediate urologic intervention:

• Sepsis with obstructing stone: Urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory before definitive treatment. 1, 2, 5
• Anuria in an obstructed kidney: Immediate decompression required. 1, 2
• Uncontrolled pain despite adequate analgesia. 2
• Impaired renal function or solitary kidney with obstruction. 2

Common Pitfalls to Avoid

• Do not delay imaging or intervention if infection is suspected—this is a urological emergency. 5
• Do not use calcium channel blockers as first-line MET, as alpha antagonists are superior. 4
• Do not continue conservative management beyond 6 weeks without reassessment. 3
• Ensure urine culture is obtained before any intervention to guide antibiotic therapy if needed. 1, 5

Monitoring During Conservative Management

• Obtain periodic imaging to track stone position and hydronephrosis. 2, 3
• Assess pain intensity regularly using standardized scales. 2
• Prescribe analgesics on a regular schedule rather than "as needed" for chronic pain, with rescue doses available for breakthrough episodes. 2
• If pharmacological therapy is used for prevention, obtain periodic blood testing to monitor for adverse effects (hypokalemia with thiazides, elevated liver enzymes with allopurinol or tiopronin, anemia with acetohydroxamic acid). 1