Yes, LED teeth whitening works when the light is used with a whitening gel: the gel does the whitening, and the blue LED speeds it up. With the SmilePro Advanced Kit that means one 10-minute treatment a day for 7 days, for teeth up to 8 shades whiter, and most customers see a noticeable difference after the first treatment.
LED teeth whitening has become one of the most popular at-home beauty treatments, but with so many products making bold claims, it's reasonable to ask how it works. This guide explains what causes stains, what the gel and the LED light each do, and what to expect from SmilePro.
What causes teeth to look yellow or stained?
Tooth staining falls into two groups: stains on the outside of the tooth, from food, drink and smoking, and discolouration inside the tooth, from injury, certain medicines in childhood or ageing. Outside stains are the most common and respond best to whitening.
Surface stains
These sit on the outer enamel and come from coffee, tea, red wine, dark berries, spices and smoking. Over time the colour compounds in these build up and darken the look of your teeth.
Stains inside the tooth
Discolouration inside the tooth can come from an injury, a root canal treatment, certain antibiotics taken as a young child (such as tetracycline), or ageing, as the enamel wears and the yellower dentine beneath shows through. Whitening gel on the outside of the teeth will not lighten discolouration deep inside a tooth; a dentist can advise on options. SmilePro will not work on stains from antibiotics, teeth affected by injury, or thin enamel.
What is in the SmilePro whitening gel?
The whitening ingredient in SmilePro's UK and European gel is PAP (phthalimidoperoxycaproic acid), with potassium nitrate and hydroxyapatite in the formula. The gel was developed by dental professionals, is enamel safe when used as directed, and is formulated to help prevent sensitivity in healthy teeth. Every ingredient is listed on the kit page.
UK and EU law limits what at-home whitening products sold to consumers may contain, which is why many at-home products sold here, including SmilePro's, use PAP. Read more in Is PAP teeth whitening as good as peroxide?
What does the LED light actually do?
The LED light does not whiten teeth on its own: the gel does the whitening. In the SmilePro kit, the blue LED speeds up the gel so each treatment takes just 10 minutes, and the red LED is designed for a more comfortable treatment. That is why the gel is always used with the light, never on its own.
Is LED teeth whitening safe?
The SmilePro light uses blue and red LEDs, not UV light, and is UKCA and CE marked. It is rechargeable and water-resistant, has a built-in mouth tray, and switches itself off after 10 minutes, so you never have to time it. Used as directed, the gel is enamel safe and formulated to help prevent sensitivity in healthy teeth. If your teeth are already sensitive, or your gums are unhealthy, see a dentist first.
How does the SmilePro system work?
- Brush your teeth with water.
- Paint a thin layer of gel onto the front of your upper and lower teeth with the pen.
- Pop the mouth tray in and press the power button. The light runs for 10 minutes, then turns itself off.
- Take it out and rinse with water. Wait 1 hour before eating or drinking anything except water.
- Do this once a day for 7 days. After that, a 10-minute top-up every 2 weeks helps stop new stains settling in.
Once you have the light, you only need refill pens: the Whitening Pen Pack has 3 pens with 30 treatments, which last over a year at one top-up every 2 weeks.
See exactly how SmilePro works on our How it works page →
What results can you expect?
| When | What to expect |
|---|---|
| Day 1 | Check your starting shade with the shade guide, then do your first 10-minute treatment. Most customers see a noticeable difference after the first treatment. |
| Days 2 to 6 | One 10-minute treatment a day. For a stronger result, you can run up to three 10-minute cycles (30 minutes) in one session, without adding more gel. |
| Day 7 | Course complete. Compare with your starting shade: up to 8 shades whiter. |
| Every 2 weeks | A 10-minute top-up keeps your result going, or once a week if you drink a lot of coffee, tea or red wine. |
Results vary with your starting shade and the type of staining.
Does the LED light alone whiten teeth?
No. The whitening is done by the gel; the blue LED speeds it up so each treatment takes 10 minutes. A light used without a whitening gel will not whiten your teeth, which is why the SmilePro gel is always used with the light.
Is at-home LED whitening as good as the dentist?
A dentist can use stronger whitening gels and lighten teeth in one appointment, and is the safest route if you have any concerns about your teeth or gums. An at-home LED kit takes a little longer, a 7-day course, at a fraction of the cost. See our full comparison: At-home vs dentist teeth whitening.
Why do some people get better results than others?
Results depend mainly on the type of staining, your starting shade and how consistently you use the kit. Surface stains from coffee, tea, red wine and smoking respond best; stains inside the tooth respond least. Regular top-ups help keep your result going.
LED kit or whitening strips?
Strips need no light and take 30 minutes a treatment; the LED kit takes 10 minutes and whitens up to 8 shades. Compare them side by side in Whitening strips vs LED kit: which should you choose?
The bottom line: does LED whitening work?
Yes, with the right gel used with the light, and used consistently over a full course. The key is choosing a kit that names its whitening ingredient, lists every ingredient, and tells you who should not use it.
SmilePro whitening products are not suitable for anyone under 18, or anyone pregnant or breastfeeding. If you have sensitive teeth or unhealthy gums, see a dentist first.
Shop the SmilePro Advanced Teeth Whitening Kit, and see how LED whitening works for yourself →
Related reading:
Sources
This guide is general information, not dental advice. If you have any concerns about your teeth or gums, speak to a dentist.
- NHS, Teeth whitening, page reviewed 19 August 2025.
- Oral Health Foundation, Tooth whitening and the law, read 7 October 2026.
- SmilePro How it works and Advanced Teeth Whitening Kit instructions and FAQ.
Last updated: 7 October 2026.
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