How to do an AI Differential Diagnosis
One of the most powerful things you can do with modern AI is perform a differential diagnosis — the same process a physician uses to narrow down what condition might explain a set of symptoms. You can do this yourself, today, for free.
The Two-Prompt Strategy
This technique works by separating two tasks: getting the most accurate medical output, then translating that output into plain English.
Step 1: Get the Professional Diagnosis
Open any capable AI (ChatGPT, Claude, Gemini, etc.) and use this prompt structure:
"You are an expert doctor diagnosing a patient. Provide a differential diagnosis based on these symptoms: [list your symptoms here, including duration, severity, and any relevant history]."
This framing is critical. By instructing the AI to act as a diagnosing physician, you force it to produce the most accurate, straightforward, and professional medical information it is capable of. The output will be detailed, clinically structured, and — importantly — will use the same medical terminology a doctor would use in their notes.
What to expect: A ranked list of possible conditions (the differential), often with notes on which are most likely, what additional tests would distinguish between them, and any red-flag symptoms that would require emergency care.
Step 2: Translate into Plain English
The output from Step 1 will be heavy with medical jargon — terms like tachycardia, idiopathic, dyspnea, or prodromal symptoms. Do not let this intimidate you.
Take the full output from Step 1 and paste it into a second AI prompt (or a new session) with this instruction:
"Please define and explain all the medical terms in the above text in plain English, as if explaining to someone with no medical background."
This second pass transforms the clinical output into something fully understandable, giving you the same information a doctor would have — in language you can actually use.
Why This Works
AI language models are trained on enormous volumes of medical literature, clinical case studies, and physician notes. When given the right framing, they produce outputs that rival the quality of a first-pass clinical assessment. The two-prompt strategy ensures you get both the accuracy of professional-grade diagnosis and the accessibility of plain-language explanation.
Important Note
This technique is for education and awareness — to help you understand what might be happening in your body and have more informed conversations with healthcare providers. It is not a substitute for emergency care. If you are experiencing chest pain, difficulty breathing, signs of stroke, or any other emergency symptom, seek emergency care immediately.