Whitening Strips Hurting Your Gums? Causes And How To Stop It

Sore gums after whitening strips are almost always caused by the gel reaching tissue it was never designed to sit on. In most cases that is a fit problem rather than a formula problem, which is good news, because fit is the part you can control.

Gum tissue and tooth enamel are not the same material and they do not react the same way. Enamel is the hardest substance in your body. Your gums are soft mucosa with no protective shell at all. A gel formulated to sit against enamel for half an hour is not formulated to sit against gum for half an hour, and when a strip overhangs, slides or is pressed too high, that is exactly what happens.

This article covers what is actually going on, how to tell ordinary irritation from something that needs a dentist, and the handful of things that stop it happening again.

Sore gums and sensitive teeth are two different problems

The two have almost nothing in common beyond both hurting.

Tooth sensitivity is a sharp, brief zing, usually triggered by cold, and it comes from the nerve inside the tooth reacting to what has passed through the enamel and dentine. It is felt in the tooth itself and it can arrive hours after you have finished.

Gum irritation is a dull soreness, tenderness or stinging along the gum line, sometimes with a pale or whitish patch where the gel sat. It is a contact reaction in soft tissue. It is felt at the edge, not inside the tooth, and you can usually point at exactly where it is.

The distinction matters because the fixes are completely different. Sensitivity is about the formula and how deep it goes, and we have set out what causes it in why whitening strips cause tooth sensitivity. Gum soreness is usually about placement. Trying to solve one with the answer to the other is a quick way to give up on whitening entirely.

Cause one, and it is the common one: the strip is in the wrong place

Whitening strips are cut to a standard shape. Mouths are not.

That means a strip can be slightly too tall somewhere, usually at the front where the gum line curves highest around the canines and central incisors. Press the strip on flat and that extra few millimetres of gel-coated film lands directly on gum rather than enamel.

Three things make it worse:

• Overhang at application. If you line the strip up with the edge of the strip rather than the edge of your teeth, you will almost always sit it too high.
• Migration during wear. A strip that does not stay put travels, and it tends to travel upwards as your mouth warms. A strip that was correctly placed at the start can be sitting on your gums twenty minutes later.
• Pressing and smoothing. Running a finger or tongue along the strip to flatten it pushes gel out from under the edges, straight onto the gum line.

The second of those is the hardest to spot, because you placed the strip carefully and assume it stayed where you put it. There are broadly two ways a strip is made to stick. Wet-fit strips rely on moisture and gel tack, which softens as it warms, so they shift. Dry-fit strips go onto clean, dry teeth and hold position. Our PAP whitening strips are dry-fit for exactly this reason, and the no-slip grip is a comfort feature far more than it is a convenience one.

Cause two: what is in the gel

Placement explains most of it. The formula explains the rest, and explains why the same mistake hurts more with some products than others.

Peroxide-based whitening works partly through free radical formation, and free radicals are the standard explanation for both the tooth sensitivity and the soft tissue irritation associated with peroxide whitening. Put that on gum tissue and you get a stronger reaction than you would from a gentler active making the same mistake.

In the UK this is capped by law. A whitening product sold directly to the public cannot contain or release more than 0.1% hydrogen peroxide, and anything between 0.1% and 6% can only be supplied through a dental practitioner. We have gone through what that means for what you can actually buy in the UK rules on teeth whitening. It is also why an overseas strip bought online can be a genuinely different proposition from one bought here.

Peroxide-free formulas take a different route. PAP, short for phthalimidoperoxycaproic acid, acts on the same coloured compounds in the stain without that free radical formation. That does not make gel on your gums a good idea, and no formula is a licence to be careless with placement. It does change how much a small mistake costs you.

Gum irritation from whitening strips: what it looks like and when to worry

Ordinary contact irritation usually looks like a pale or white patch on the gum where the gel sat, sometimes with a red margin around it, and feels tender or slightly raw. It typically settles on its own within a day or so once the gel is gone.

What it should not do is persist, spread or worsen. Speak to a dentist if:

• the soreness has not settled after a couple of days
• the gum is bleeding, ulcerated or peeling
• the pain is severe rather than tender
• it keeps happening every single time despite correcting your placement
• your gums were already sore, bleeding or receding before you started

That last one matters. Whitening is a cosmetic product and it does not treat anything. Putting it on top of an existing gum problem tends to make the problem more obvious, not better. The Oral Health Foundation puts it plainly on its tooth whitening page: whitening may not be suitable for everyone. If something was already wrong, get that looked at first. Whitening will still be there afterwards.

Pure Glow is not suitable for children under 12. If you have any concern about your gum health generally, speak to a dentist before using any whitening product.

Why did my gums turn white after whitening strips?

That white patch is the gum tissue reacting to contact with the gel. Temporary whitening of the gums after peroxide gel touches them is a known reaction, and it usually fades within hours as the tissue settles. Gel left on the gum can cause a reaction whatever the active ingredient is, so treat it as a sign the strip sat too high or moved during wear.

Rinse with water, leave that area alone, and correct the placement next time. If the patch does not settle, or there is pain or blistering, stop using the strips and see a dentist.

Why this is the problem I built the brand around

Before Pure Glow I spent fifteen years at Jaguar Land Rover, six of them in health and safety. That is not dental expertise and I would not pretend otherwise. What it leaves you with is a particular reflex: when the same thing keeps hurting the same people, you do not write it off as the cost of doing business. You go and find out why.

I came to whitening as a customer. Shift work, too much coffee and smoking at the time meant my teeth stained, and a holiday to Ibiza was what finally made me do something about it. The peroxide strips I tried gave me real sensitivity. The non-peroxide ones I switched to would not stay on at all. In Ibiza I went through three sets and not one of them stuck. That was roughly a fiver straight in the bin by the pool, and gel everywhere it should not have been.

I turned to my girlfriend and told her I was going to make my own and fix it. She told me I was crazy.

Back home I bought every whitening strip I could get hold of and wrote down every fault. Three suppliers would not engage with any of it and just wanted to keep shipping the same cheap product. I eventually found a supplier in America working with a manufacturer who actually wanted to solve it. That took ten months and four rejected formulas.

The dry-fit decision came out of that list, and it was not really about tidiness. A strip that stays where you put it is a strip that is not depositing gel along your gum line for half an hour. Whitening pain at the gum line can be a product design problem wearing a chemistry costume.

How to stop it happening

None of this is complicated and most of it is placement.

• Brush, rinse, dry, then wait a few minutes. Wet-fit, gel-coated strips are the ones that travel, and a quick wipe with a towel is the usual workaround for those. Ours grip even when your teeth are wet.
• Line the strip up with your gum line, not with the strip. Sit the top edge just below where tooth meets gum and leave a visible sliver of tooth showing. A millimetre of unwhitened enamel at the top is invisible. Gel on your gums is not.
• Fold the excess behind your teeth. The overhang is meant to wrap the back surface, not to climb your gums.
• Press on the teeth, not along the edge. Smooth the strip against the flat face of each tooth rather than running a finger along the top edge, which squeezes gel upwards.
• Wipe any gel that does reach the gum. A clean finger or a tissue, straight away. Do not leave it there for the full wear.
• Wear for a minimum of 30 minutes and do not double up. Two strips in one day does not halve the course. It just doubles the contact time on whatever the gel is touching.
• If it stings, take it off. Discomfort during whitening is information, not a sign it is working. A product that tells you to push through it is asking you to ignore the only feedback you have.

If you want the full routine rather than just the gum-related parts, it is in how to use whitening strips properly. And if you are weighing up which product to start with in the first place, our whitening strips are all peroxide free and dry-fit, and you can see both packs in one place.

Frequently asked questions

Are whitening strips supposed to burn?

No. A mild tingling on the teeth during a course is common and usually passes. A burning or stinging sensation along the gum line is not something to work through, and it normally means gel is sitting on soft tissue. Take the strip off, rinse, and reposition it lower next time.

How long do burned gums from whitening take to heal?

Ordinary contact irritation usually settles within a day or two once the gel is removed and not reapplied to the same spot. If it is still sore after that, or if there is bleeding or ulceration, that is a reason to see a dentist rather than to wait it out.

Can I carry on with the course if my gums are sore?

Give them time to settle first, then restart with the placement corrected. Carrying on over already irritated tissue is how a one-off becomes a fortnight of soreness, and it is how a course ends up abandoned halfway.

Do peroxide-free strips still irritate gums?

Gel on gum tissue can cause a reaction whatever the active ingredient is, so placement still matters. What changes is the margin for error: peroxide-free PAP strips avoid the free radical formation associated with peroxide sensitivity and soft tissue irritation, so the same small mistake tends to cost less.

My gums went white after using whitening strips. Is that normal?

A temporary pale patch where the gel sat is the classic sign of contact irritation and it usually fades as the tissue settles. It is a sign the strip was sitting too high, so treat it as placement feedback. If the patch does not fade, see a dentist.

Why do my gums feel bruised after whitening strips?

A bruised, tender feeling along the gum line usually comes from the strip being pressed hard onto the gums rather than onto the teeth, sometimes with gel sitting there too. Press on the flat face of each tooth instead and it normally eases. If the soreness does not settle, see a dentist.

Can whitening strips make your gums bleed?

They should not. Bleeding gums are a reason to stop the course and see a dentist, not something to work through. Bleeding can also point to a gum problem that was there before you started, and whitening does not treat anything.

Which strips are best if my gums are easily irritated?

Look for a strip that stays where you put it, because migration is the main cause, and a peroxide-free formula for the margin it gives you. Ours are dry-fit and peroxide free, which is why we make whitening strips for sensitive teeth. There is more on what to look for when choosing in our buyer's guide.

The short version

If whitening strips are hurting your gums, the strip is almost certainly sitting too high or moving while you wear it. Lower the placement, dry your teeth first, stop smoothing the top edge, and wipe away anything that escapes.

What it is not is a sign that whitening is not for you. That conclusion is the expensive one, because it can stop you trying again after one bad experience with a product that was never going to stay where you put it. Fix the fit and the problem usually disappears.

That is the entire reason Pure Glow exists, and it started with three useless sets of strips by a swimming pool.

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Related reading:

• Peroxide-free teeth whitening
• Are whitening strips bad for your teeth?