T-01
Azelaic acid application-quantity guide
Fingertip-unit sizing for the areas you treat: FTUs per application, grams per application, per day and per week, and how long a 30 g or 50 g tube lasts at label frequency.
Fingertip-unit sizing for the areas you treat: FTUs per application, grams per application, per day and per week, and how long a 30 g or 50 g tube lasts at label frequency.
Unlike the research compounds in this fleet, azelaic acid HAS an established regimen: the labels prescribe a thin layer twice daily (morning and evening) on cleansed, dry skin. The tools quantify that regimen; they do not invent doses. Where a quantity is not label-published (like a 10% serum), the tool says so instead of guessing.
Only three area rows ship because only these are published or one-step derivable from published sources. The 1991 FTU study did not subdivide the face into forehead/cheek/chin zones and neither do we: inventing per-zone allocations would be fabricated precision.
Labels prescribe twice daily (morning and evening). The calculator defaults to 2 and flags any other frequency as off-label.
Quantity plan
Select at least one body area to size the application.
Worked example
Worked example: a 12-week gel course on the FTU standard
- Face and neck = 2.5 FTU per application (published FTU allocation).
- 2.5 FTU x 0.5 g = 1.25 g per application.
- 1.25 g x 2 applications per day = 2.5 g per day.
- 50 g tube / 2.5 g per day = 20 days per tube.
- The gel label runs the diagnosis-reassessment clock at 12 weeks (84 days): 84 / 20 = about 4.2, so plan on 4 to 5 tubes for a full course.
- Cross-check: the foam label measured 0.94 g per whole-face application, which puts the same course near 2 g per day; the two published anchors bracket a 20 to 26 day tube life.
Label quantities at a glance. Reference only; each row cites its label.
| Product | Strength | Pack | Frequency | Application | Source |
|---|---|---|---|---|---|
| Azelaic acid gel 15% (Finacea and generics) | 15% | 50 g tube | Twice daily | Thin layer, massage into affected areas on the face | source |
| Finacea Foam 15% | 15% | 50 g pressurized can | Twice daily | Entire facial area; smallest amount that covers with a thin layer; measured mean 0.94 g per application | source |
| Azelex cream 20% | 20% | 30 g or 50 g tube | Twice daily | Thin film, massage gently but thoroughly into affected areas | source |
Frequently asked questions
Why fingertip units instead of just saying a pea-sized amount?
Because FTUs are the only published, quantified convention: one FTU is about 0.5 g and covers about 286 square centimeters, and face and neck take 2.5 FTU in the defining study. Pea-sized is folklore; these are measured numbers with citations.
Why does the guide have no preset for 10% serums?
Cosmetic serums have no labeled application quantity to cite: no FDA-reviewed label exists for them. The FTU arithmetic still works for any product if you know your tube size in grams, but the presets only encode label-published or FTU-published numbers.
Will applying more work better?
No data supports that, and the labels point the other way: apply a thin layer, and the foam label specifies the smallest amount necessary to cover. More product mainly buys more of the burning and stinging that 29% of gel users already report.
How many tubes does a full course take?
At the FTU-standard 2.5 g per day for face and neck, a 50 g tube lasts 20 days, so the gel label's 12-week reassessment window spans 4 to 5 tubes. The foam-measured 0.94 g per application stretches a 50 g can to about 26 days.
Tools: educational calculators and references only.