Dr Tim Pearce
Most of the lines that patients complain about when it comes to lips are vertical, but there’s a minority of patients who develop a horizontal lip line that can be equally concerning, also known as the “second smile”. This horizontal lip crease troubles some patients, whereas others actually find it quite endearing and like that particular line. As aesthetic clinicians, our job is to identify who will benefit from treatment and who will not, ensuring we get the best result both psychosocially and aesthetically.
The key to successful treatment lies in understanding what’s driving the formation of this crease. The horizontal lip line is caused by the muscles around the nose and upper lip, and this is actually quite variable between different patients.
In some patients, the crease will be caused predominantly by the action of the depressor septi muscle and its connections in that area of the face. In other patients, it may be the orbicularis oris muscle, and the levator labii alaeque nasi plays a role in some cases.
In many patients, it can be any combination of the lip elevators contributing to the formation. This is particularly true when a patient has a strong nose with good lip elevation – they’re very likely to develop a crease. The contributing muscles can include:
You can see how this could be very difficult to treat because you cannot neutralise all of those muscles without causing significant functional issues.
When it comes to treating the horizontal lip crease, we’re looking for patients who are somewhere in the middle of the spectrum. If you’ve got a patient with very powerful lip elevation and a strong nose, you’re unlikely to be able to stop that crease with Botox and dermal filler.
However, if the crease is milder and smaller, and the muscles involved tend to be a little bit on the weaker side but still enough to cause a crease, you’ve got more of a chance of improving the situation.
It’s crucial to note that removing something a patient likes is never a good thing to do. Some patients actually appreciate their horizontal lip crease as it can make their lips appear bigger when they smile – the lip rotates and rolls upwards during animation. As a clinician, you should never treat this feature until the patient becomes bothered by it.
You can treat this problem in multiple different ways and with different modalities. Like any crease in the face, it’s a combination of what is happening to the tissue and the effects of the muscle on the tissue.
Often, we would think first to treat the muscles causing the crease. The goal is to relax muscles in certain parts of the face without disharmonising the facial expression. We want to create a beautiful smile without the distraction of the line if that’s what the patient perceives.
This can be done with very small amounts of botulinum toxin to slightly neutralise some of the muscle that’s curling up the lip. For example, the levator labii alaeque nasi often curls around, affects the nostril, but also curls into the lips, actually pulling the surface upward.
Dermal filler can also be effective in some patients as it acts like a mechanical block of the muscle. As you add volume, the muscle has to contract harder against dermal filler. This is a common way to treat a gummy smile, and in many cases, it can be easier to create a harmonious smile because mechanical blockage is a little bit gentler.
This approach is particularly useful when the patient already has some volume loss. If you have a patient with a horizontal lip crease, nasolabial folds, and volume loss, you should definitely be considering dermal filler in the treatment plan.
The philtral columns are usually what becomes disrupted by this crease. As the lip rises up, the tissue bends and the philtral columns are dissected by the crease. You can get some benefit from directly treating the philtral columns with filler.
While this isn’t massively powerful on its own, it works better when done in conjunction with other treatments and can soften the crease in some patients. This is a better course of action in most people than directly filling the crease itself.
If you directly treat the horizontal line with filler, this can create various disharmonies. The most important issue is that you start to make the white lip compete with the pink lip – you now have a projecting white lip next to a relatively smaller pink lip. It simply doesn’t look natural.
While tiny amounts of a low-viscosity product might soften the line just enough in some patients, you really have to rein yourself in from trying too hard, or you’ll alter the shape and create the unnatural “Homer Simpson” appearance that we’re often trying to avoid when treating upper lip lines.
It’s worth remembering that if you volumise a lip incorrectly, this can actually have the opposite effect. You’ll often see patients who’ve been overtreated develop new creases because of the impact of having a large amount of dermal filler right next to tissue that hasn’t got any additional strength.
A strong lip rises up and compresses tissue above, and they develop an upper lip line crease, or even more commonly, a vertical crease that creates an unnatural appearance where the cheek meets with the upper lip. This is caused by having a large amount of product next to an area that hasn’t been treated, creating a new focus for weakness.
When treating the horizontal lip crease, you must consider potential downsides. If you completely stop the muscle contraction that creates the crease, you might also lose upper lip show during smiling. The muscles that create the crease are often the same ones that allow the lip to rotate and roll upwards, making lips appear bigger during animation.
This could result in a patient getting rid of the crease but losing the show of the top lip – a trade-off that many patients wouldn’t want.
The horizontal lip crease presents a unique challenge in aesthetic medicine. Success depends on careful patient selection, understanding the complex anatomy involved, and using the right combination of treatments. Most importantly, we must recognise that this feature isn’t always a problem to be fixed – for some patients, it’s a characteristic they appreciate and want to keep.
As aesthetic practitioners, our role is to assess each patient individually, understand their concerns and preferences, and provide honest guidance about what’s achievable. When we do treat, a gentle approach using combination therapies often yields the best results while maintaining natural facial expression.
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