List each medicine once on the Medicines tab — buy price, sell price and reorder level — and record every batch you receive on the Stock tab with its quantity and expiry date. Stock on hand rolls up automatically, and each medicine is flagged OK, LOW or OUT. Every batch shows its days to expiry and a status — OK, Expiring (within 90 days) or EXPIRED in red — so you pull the reds off the shelf before they cost you.
Set today's date on the Dashboard and it stays current: total stock value, how many lines are low, and exactly what is expiring soon or already expired. The cells you type into are yellow; the formulas are locked. It opens in Excel or Google Sheets, so you can keep it on the counter or on your phone.