GlowproofHow long to try a new skincare product before you decide
Give a new skincare product 14 days to see how it feels, 28 days to see how it fits your routine, and up to 42 days to compare photos. Change only that one product, keep notes and same-light photos, and write your verdict on the last day. The label and a professional outrank any rule of thumb.
Coming soon to iPhone
Why is there no single answer?
Products differ, skin differs and the thing you are hoping to notice differs. A moisturizer can feel comfortable or not on day one. Something aimed at texture or tone is judged over weeks. Brands put a time on the label or in their leaflet for a reason, so read it first. Wikipedia's article on skin care also notes that little is known scientifically about the clinical efficacy of many routine practices, and that routines are often based on personal beliefs and preferences. That is a good reason to keep your own record and not trust a number from a stranger.
This page is about how to run a fair trial. It does not predict what any product will do.
What do 14, 28 and 42 days mean?
Think of three checkpoints rather than a deadline.
The numbers are also practical. The Wikipedia article on the epidermis says the entire epidermis is replaced by new cell growth over about 48 days. That is one reason people judge a product over several weeks and not over a few mornings. Skin changes slowly, and a day-three opinion is mostly about the product's texture and smell.
| Length | What you can judge | What you cannot judge yet |
|---|---|---|
| 14 days | Feel, comfort, fit with the rest of the routine | Gradual changes |
| 28 days | Whether you still like using it, early photo differences | Slow changes |
| 42 days | Photo comparison across several weeks | Anything beyond that |
How do you set up a fair trial?
A fair trial has one change. If you start a serum and a new cleanser on the same day, the notes cannot tell you which one deserves the credit or the blame. Follow these steps.
The photo step matters more than people expect. Light changes how skin looks from one selfie to the next, which is why the lighting guide is worth reading before you begin.
- Pick one product and write its name and start date.
- Decide the length: 14, 28 or 42 days.
- Keep every other product and habit as steady as you can.
- Take a photo each day in the same light, at the same distance.
- Write one line a day: how your skin feels, and what else happened.
- On the last day, compare the first and last photos and give a rating.
What should you write each day?
Short notes beat long ones. Use the same few words each day so you can scan them later. How does your skin feel today? Calm, oily, dry, breaking out, sensitive or irritated are enough. Then add anything unusual: poor sleep, travel, stress, a new food, a change in weather. These notes do not prove a cause. They give you context when you read the month back, so a rough week is not blamed on the product by default.
When should you stop early?
If a product stings, burns or causes a strong reaction, stop using it. Do not wait for day 14 to finish the trial. Washing it off and asking a pharmacist, a doctor or a dermatologist is the sensible step, and so is keeping the packaging so that you can show the ingredients. A diary is not a medical tool, and a trial is never a reason to push through discomfort.
How do you judge the result fairly?
Compare the first and last photos, taken in matching light, and read your notes. Ask three questions. Did I like using it? Did anything change that I can see in matching light? Would I buy it again at the price I would pay? Your answers can be mixed, and that is fine. A product can feel lovely and show no difference. It can show a difference and be unpleasant to use.
Write the verdict in your own words and give it a rating from 1 to 5. Then decide: keep using, not for me, or try again later in a different season.
What does Glowproof add to a trial?
Glowproof, an iPhone skin photo diary in development, has a feature called Product Trials. You name the product, choose 14, 28 or 42 days and optionally pick an area to watch, such as the cheeks or chin. Glow Checks and routine check-offs are collected under that trial, and at the end you rate it from 1 to 5 and choose Keep using or Not for me, with an optional note. The rating is stored exactly as you set it. The app suggests no products and does not compute a verdict. See routine and Product Trials for the full flow.
The light check also helps: it compares the brightness, left and right balance and warmth of each photo with your Day 1 photo, so that a darker bathroom does not pass for a change in skin.
Can you run two trials at once?
Avoid it. The whole value of the method is the single change. If you want to try two products, run them one after the other with a gap of a week or two in between. On the free plan Glowproof allows one active trial at a time, which fits this advice anyway.
What if the product is a replacement, not an addition?
Swapping a cleanser or a moisturizer is easier to judge than adding a new step, because the routine keeps its shape. Treat the swap as a trial all the same: note the date, keep everything else steady and give it the same two or four weeks. A replacement that feels slightly different on day two may feel normal by day ten, so the early notes are about comfort and the later ones are about whether you want to keep using it.
Does the season matter?
It can. Humidity, heating and cold air change how skin feels, which can blur the result of a trial. If a month starts in a dry spell and ends in a damp one, say so in your notes. A tag such as travel or weather change next to the date helps you read the month honestly. For a product you care about, a second trial in a different season is a fair way to check your first impression.
Frequently asked questions
How long should I try a new skincare product?
A common approach is 14 days for feel, 28 days for fit and up to 42 days for photo comparison. Always read the label first.
How do I know if a skincare product is working?
Compare photos taken in matching light at the start and end, and read your daily notes. Change only one thing during the trial.
When should I stop using a new product?
Stop if it stings, burns or causes a strong reaction, and ask a pharmacist, doctor or dermatologist.
Can I test two skincare products at once?
It is better not to. With two changes, you cannot tell which one caused what you notice.
Does Glowproof tell me if a product works?
No. It stores your photos, notes and rating, and the verdict stays yours.
Keep exploring
Routine and trialsYour own AM and PM checklist, reminders, and 14, 28 or 42 day Product Trials.How to Patch Test a New Skincare Product and Log ItA plain at-home patch test routine for a new skincare product, with a log template and when to ask a professional.Consistent lightingWindow light, color temperature, flash, exposure and distance: a checklist for matching photos.How often to shootDaily, every few days or weekly: how to choose a rhythm and when to compare.