Peanuts and kidney stones

Kidney stones form when minerals in urine become concentrated and crystallise. Peanuts contain oxalate, a substance that can combine with calcium in urine for people who form calcium oxalate stones. That does not mean every person with stones must avoid peanuts. Stone composition, urine findings, overall diet, kidney function, and fluid intake all change the advice. Eating a calcium-containing food with a meal may affect how oxalate is handled in the gut, but a clinician should personalise recommendations. [Dehydration](/conditions/dehydration/) can make urine more concentrated, so fluid habits matter alongside any single food.

Keep a record of foods, fluid intake, and any previous stone analysis to discuss at a [GP Consultation](/treatments/consultations-and-assessment/gp-consultation/). Do not sharply restrict nutritious foods without guidance. Spread fluids through the day unless a clinician has limited your intake, and follow advice about salt and other dietary factors. If a stone is suspected, assessment may include urine tests and imaging such as an [Abdominal Ultrasound](/treatments/diagnostics-and-screening/abdominal-ultrasound/). A plan based on your stone type is more useful than treating peanuts as a universal cause.

Get urgent medical care for severe or worsening [Flank Pain](/symptoms/flank-pain/), fever or chills, repeated vomiting, or feeling very unwell. Prompt assessment is also needed for [Difficulty Passing Urine](/symptoms/difficulty-passing-urine/) or markedly reduced urine, because a blocked urinary tract can become serious. Blood in urine, [Painful Urination](/symptoms/painful-urination/), or persistent [Abdominal Pain](/symptoms/abdominal-pain/) should be assessed, particularly when accompanied by fever. Do not wait for diet changes to settle intense symptoms.

What type of stone do I have, if known? Should I limit peanuts or other oxalate-rich foods? How much fluid is suitable for me? Do I need urine testing, stone analysis, or imaging? Which symptoms require same-day care?