South Kensington
- 20 Old Brompton Road, London SW7 3DL
- Open seven days a week
- 020 7183 2362
Treatment comparison · Wimpole Street, Marylebone
Dentist-prescribed whitening or a shop-bought kit: what the law and the results actually look like
Whitening strips, pens and LED gadgets are easy to pick up on the high street, and the packaging often promises much the same outcome as a dental practice. The difference between the two is not a matter of branding. UK regulation caps the peroxide that can be sold to the public at 0.1%, and reserves anything stronger for products prescribed by a dentist after an examination. At Wimpole Street the prescribed option will be the Boutique home system, worn in trays moulded to your own teeth.
Decision guide
Which is right for you?
Choose Dentist-prescribed whitening if…
- You want a shade change you can actually see, with an even result across every tooth.
- You have sensitive teeth or receding gums and would like the gel kept away from soft tissue.
- You have not had a check-up recently and would value an assessment before bleaching anything.
- You would like trays you can keep for occasional top-ups over the coming years.
Choose Over-the-counter whitening if…
- Your teeth are already fairly light and you are after a small lift before an event.
- Budget is the main constraint and you accept that the change may be slight and temporary.
- You have recently had a dental examination and know there is no untreated decay or gum disease.
- You are curious about whitening but not yet ready to commit to a dental appointment.
At a glance
Side by side
| Feature | Dentist-prescribed whitening | Over-the-counter whitening |
|---|---|---|
| Peroxide strength | Up to 6% hydrogen peroxide, available only on a dentist’s prescription | Capped at 0.1% hydrogen peroxide under UK law |
| Who checks your teeth first | A dentist examines gums, enamel and existing fillings before prescribing | No one; you judge suitability yourself |
| Tray fit | Made from a scan of your teeth so gel sits evenly and off the gums | Strips or one-size trays that may slide, leak or miss areas |
| Typical result | Up to eight shades lighter, evenly distributed | Variable; often a subtle change, sometimes patchy |
| Time to result | One to two weeks of daily wear at home | Days to weeks depending on the product |
| How long it lasts | Around 12 to 18 months with sensible habits | Weeks to a few months before fading |
| Fee | £399 including custom trays | Roughly £10 to £50 per product |
| Top-ups | Reuse your trays with additional gel syringes | Buy the product again from scratch |
| Wear options | By Day formula for one hour, or By Night worn while sleeping | Set by the manufacturer |
| Best suited to | Anyone wanting a noticeable, lasting result under supervision | Light staining, a limited budget and realistic expectations |
In the chair
What the treatment involves
Dentist-prescribed whitening
The dentist first looks for anything that would make whitening unwise: active decay, gum inflammation, cracks or exposed root surfaces. If all is well, a digital scan is taken and the laboratory makes thin, close-fitting trays with small reservoirs over the front of each tooth. You collect the trays with a supply of Boutique gel and choose between the By Day formula, worn for about an hour, and By Night, worn while you sleep. Most people finish the course in one to two weeks, with the practice on hand if sensitivity or questions arise. The trays are yours to keep for later top-ups.
Over-the-counter whitening
You buy strips, a pen, a gel or a generic tray kit, read the instructions and apply the product yourself, typically once or twice a day for the period stated on the box. Because the peroxide is limited to 0.1%, most of the visible change comes from lifting surface stain rather than altering the colour inside the enamel. Strips and stock trays fit approximately, so gel can pool on the gums or miss the edges of teeth, and any results tend to fade within weeks. Products bought from unregulated online sellers may exceed the legal limit and carry risks of their own.
Fees
Cost and longevity at Wimpole Street
Boutique home whitening at Wimpole Street will be £399. That figure includes the examination, the scan, custom trays and the initial course of gel. Shop-bought products vary from about £10 to £50: strips typically £15 to £40 a pack, pens and gels £10 to £30, and generic tray kits £20 to £50.
The gap narrows over time. A prescribed course usually holds for 12 to 18 months and can then be refreshed with a syringe or two of gel in your existing trays, whereas shop products fade within weeks to months and must be bought again each time. Anyone who ends up repurchasing kits several times a year may spend a similar amount without reaching the same shade.
All prices are indicative and are confirmed in a written treatment plan at your consultation. Fees are the same at every Medical & Dental clinic.
Weighing it up
Strengths and trade-offs
Dentist-prescribed whitening
Strengths
- Sixty times the peroxide concentration permitted in shop products
- Oral health checked before any gel goes near your teeth
- Custom trays give an even result and protect the gums
- Results of up to eight shades, lasting around a year or more
- Trays kept for inexpensive top-ups
Trade-offs
- Higher initial cost than a kit from the chemist
- Needs an appointment for the assessment and scan
- Shade change builds over one to two weeks rather than overnight
- Temporary sensitivity is possible during the course
- Not everyone is suitable; some patients are advised to wait or treat other issues first
Over-the-counter whitening
Strengths
- Low cost, typically £10 to £50
- Available immediately without booking anything
- Reasonable for mild surface staining
- Easy to try with little commitment
Trade-offs
- Gel limited to 0.1% peroxide, so the change is often slight
- No examination, so decay or gum problems can go unnoticed
- Ill-fitting strips can whiten unevenly and irritate gums
- Results usually fade within weeks
- Cannot shift discolouration that sits inside the tooth
- Unregulated online products may contain illegal strengths
FAQ
Common questions
UK and EU cosmetics regulation treats hydrogen peroxide above 0.1% as something that should only be used after a dental examination, because bleaching teeth with unrecognised decay, cracks or gum disease can cause pain or damage. Dentists may prescribe up to 6% precisely because they have checked the mouth first.
It can, which is one reason the trays matter. Close-fitting trays keep the gel on enamel and away from the gum margin, and the dentist can suggest a shorter wear time, a desensitising toothpaste or the gentler By Day formula if teeth begin to twinge. Any sensitivity normally settles within a day or two of finishing.
No. Peroxide lightens natural enamel and dentine only, so existing white fillings, veneers or crowns on front teeth stay the shade they were made. This is one of the things the dentist looks for at the assessment, and in some cases restorations are replaced afterwards to match the new colour.
Most people find a top-up is worth considering after 12 to 18 months, sooner if tea, coffee, red wine or smoking feature heavily in daily life. Because you keep your trays, a top-up simply means collecting extra gel and wearing them for a few nights.
The light itself does very little; the active ingredient is still the gel, and in shop kits that gel is limited to 0.1% peroxide. Products marketed alongside lights sometimes come from outside UK regulation, so it is worth checking the peroxide content before using anything you cannot trace to a reputable seller.
Yes. Whitening assessments and tray fittings are available now at South Kensington and St Paul’s at the same £399 fee, and the Wimpole Street diary opens on 1 October 2026. If you begin elsewhere, your trays and records carry over for any later top-ups in Marylebone.
Marylebone, W1
Wimpole Street opens 1 October 2026
Register your interest and we will contact you when the Marylebone diary opens. If you would rather not wait, the same clinicians can see you at South Kensington or St Paul's now.
Related treatments at Wimpole Street
Opening 1 October 2026
Wimpole Street is not yet seeing patients. Until then, please book or call our South Kensington clinic on 020 7183 2362 or our St Paul's clinic on 020 7183 3709. Questions about the new clinic: wimpolestreet@md.co.uk.
Until we open
Need an appointment before 1 October 2026?
The same clinical team already works from two other Medical & Dental clinics. Book at either one now and, if you prefer, move your ongoing care to Wimpole Street once the doors open.
St Paul's, City of London
- 5 Ave Maria Lane, London EC4M 7AQ
- Open Monday to Friday
- 020 7183 3709
