1. Start with the intended use
Write down the exact product name and item or reference number. Open its current instructions and locate the intended use. Do not assume a product described as irrigation saline has an inhalation, eye-care or injection indication. Similar packaging is not evidence of matching uses.
If the listing and the physical label disagree, resolve the difference with the supplier before purchasing for a particular use. This guide compares buying information; it does not choose a treatment or override instructions from a qualified clinician.
2. Record the concentration as printed
Keep the percentage with the product name in your notes. Do not drop a decimal point or treat different concentrations as price variants of one item. A comparison table should preserve the wording on the exact product, even when a marketplace search groups several products together.
3. Separate volume from unit count
Record both milliliters per sealed unit and units per pack. For a hypothetical pack of 50 units containing 5 mL each, the total packaged volume is 250 mL. That arithmetic describes quantity only. It does not establish how a product should be used or how long an opened unit can be kept.
Check whether the seller is offering a single vial, retail box or outer case. Manufacturer case quantities and retailer pack quantities can differ. Our source-linked product notes make that distinction visible.
4. Check the total price you will actually pay
For a fair cost calculation, use the purchase price after applicable discounts plus required delivery and other charges. Keep a dated note of any subscription condition or minimum quantity. A recurring subscription offer should not be silently compared with another seller's one-time purchase price.
Cost per sealed unit equals total price divided by unit count. Cost per milliliter equals total price divided by total packaged volume. The calculator shows both figures without assuming the products are equivalent.
5. Keep the evidence with the comparison
Save the source URL and date, exact item number and relevant label wording. Mark facts you could not verify as unknown. If your decision depends on a product's route, age suitability, storage or handling, inspect those instructions directly rather than inferring them from reviews.
Sources
This checklist is our original buying methodology. The product-specific examples are linked in the product notes and source register. Numerical examples in this article are hypothetical.