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March 19, 2026
Dr Tim Pearce
When injecting the lips with dermal fillers, you might ask yourself, which injection technique is riskier for my patients – a vertical injection which crosses at a right angle to the vermillion border, or a horizonal injection which runs in parallel with this defining line of the lip? Well, you are not alone, this is a question which appears to divide the aesthetic industry, even amongst high profile aesthetic injectors. Dr Tim Pearce has sought input from many, including his social media followers, and it seems that there is an equal split between those who are for and against each of the two techniques.
So, in this blog, Dr Tim will review lip anatomy and explore the differences between vertical and horizontal lip filler injection techniques and discuss the evidence behind their safety and potential risk of causing a vascular occlusion. Which technique do you favour?
Dr Tim will be discussing more medical aesthetic training tips as part of his upcoming webinar series, so if you’re looking to increase your CPD-certified learning and want to learn more skills to make you a better practitioner, then step one is to register for the free webinars by Dr Tim.
Different opinions on injecting the lips with filler
Before we delve into the nuts and bolts, Dr Tim would like to explain why he has chosen to explore this topic.
Recently, he was approached by another expert aesthetic injector, Dr Steven Harris who had spotted one of Dr Tim’s previous videos in which he explained his theory that a vertical injection into the lip might be less likely to cause a vascular occlusion than a horizontal approach. Dr Harris disagreed with this hypothesis and sent Dr Tim an interesting clinical paper for him to review. You can follow Dr Steven Harris on Instagram.
Dr Tim was curious to see what others thought, so he questioned his social media followers and found that there was no consensus opinion, with the audiences in a fifty-fifty split on which of the techniques is riskier. This highlights confusion amongst practitioners and an absence of clear thinking and understanding on the topic, so let us look a little deeper.
Understanding your mental model of the lip anatomy
As aesthetic clinicians, Dr Tim believes that it is important that we all work to our own mental model which allows us to have a 3D visualisation of the anatomy and the differing approaches to it – both depth and angles, plus a clearing understanding of the risks posed when treating a patient in a specific area. By having this mental model, you can apply any technique you choose and understand the implications of that choice, bearing in mind that extremes of techniques, such as those which use multiple vertical injections, overfill the lips, or conform to so-called Russian, Devil, or Octopus lip trends will by their nature increase the risks to patient safety.
Every injection you deliver is a balance between benefit and harm and every point of injection will vary that balance and risk. In many cases, a desired aesthetic result may necessitate a vertical injection approach because the same cannot be achieved with a horizontal injection, understanding your mental model of the lip anatomy will allow you to achieve that safely.
Assessing which injection technique is more likely to cause a vascular occlusion
Let us consider a comparison of two different angles of entry into the lip, but with all the remaining variables consistent – the same entry point, the same depth of injection, the same dermal filler product, the same volume delivered in one single injection – so the question posed is which one is more likely to cause a vascular occlusion – the vertical angle or the horizontal one?
We can address this by reviewing two factors and one governing principle – factor one is what is the likely anatomy of the labial artery in the average patient, and factor two is what is the precise nature of the injections we are comparing? The governing principle is that the riskiest injection is likely to be the one where the injecting needle is likely to deposit the most amount of product nearest to the likely position of the labial artery. In this context, the use of the term ‘likely’ is denoting that this is a probability game, we do not know with certainty where the labial artery is positioned in the average patient, but we know its probable position, but this can vary.
According to a review of clinical papers, the likely position of the superior labial artery is that it usually runs slightly above or within the vermillion border. It also predominantly runs beneath orbicularis oris (in approximately 60% of cases), sometimes within this muscle (35%), but on occasion it can be on top of oribicularis oris (5%). It can also be present at different depths of the muscle within the same patient.
There are rare anomalous versions of this artery too. Dr Tim recently discussed this with Julie Horne when she shared a video showing an artery pulsating near the wet-dry border – this is a known medical phenomenon called a calibre persistent artery, found in approximately 2-3% of individuals. You can see this video on Julie’s Instagram feed.
Looking at this histological cross section of a lip, it highlights some of the most important anatomy within the area. We see the location of the labial artery, the orbicularis oris muscle that runs down the centre of the lip, anterior to that we see some hypodermic fat, and then the dermis. When you picture where your injection will be placed, it is on that anterior surface, whether your approach is horizontal or vertical.
The vertical injection approach
Your needle enters the pink part of the lip with a superficial injection avoiding the deeper part of the lip envelope – because the main aim is to rotate the lip upwards in most cases – and progressively moves away from the most likely position of the labial artery. If the most likely position is behind orbicularis oris, the injection should start parallel to it and as it goes deeper in should be moving slightly further away.
The horizontal injection approach
This technique is virtually the same, but the needle will be running over and adjacent to the labial artery and staying in that plane for the entire journey of the needle. Therefore, there is more time spent close to the artery, but at a superficial depth this should avoid contact. However, with anomalous anatomy, there is more chance of encountering and cannulating the artery with this technique.
Dr Tim notes that with normal variation, in a young patient, he cannot see how a horizontal injection would be less likely to catch the artery than a vertical injection because most of the time the needle would be away from it in the latter approach.
Everything is not always as it seems with lip anatomy
Of course, every day is a school day so it is always worth questioning one’s own mental model to establish if there are circumstances where it might not apply in the way that you are picturing.
This reflection led Dr Tim to consider the additional factor related to anatomical changes through ageing – a young lip versus a more mature lip. Older patients tend to have much smaller and thinner lips as they involute, almost disappearing entirely due to atrophy in the vermillion border.
In such patients, your mental model will be altered. Attempting to use a vertical injection technique in an individual with small or atrophied lips – which is probably not the best treatment approach, but we will discuss it anyway – you are naturally going to be heading towards the space in the retro-orbicularis oris which is where the labial artery resides, therefore, your risk of vascular compromise is increased for this category of patient when using a vertical injection technique.
The conclusion from this reflective comparison is that in certain circumstances the risk profile might be different for the same injection technique.
So, do we really have an answer for the debate on vertical injection techniques versus a horizontal approach? Dr Tim Pearce is keen to know which technique you prefer and your thoughts on which is the most dangerous. You can follow Dr Tim to discuss on Instagram.
Aesthetics Mastery Show
Vertical Lip Technique
This blog follows our recent Aesthetics Mastery Show, in which Dr Tim Pearce discusses whether vertical lip injection techniques like tenting are more or less likely to cause a vascular occlusion than horizonal lip techniques, looking at the evidence for both perspectives. He also discusses lip anatomy and shares his mental model of how the two lip injection techniques are more or less likely to occlude the artery.
Are you still anxious about delivering cosmetic injectables safely?
If you want to learn more about mastering medical aesthetic treatments and complications or conquering the anxiety of where to place your needle, then register for the next Dr Tim webinar.
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Dr Tim Pearce eLearning
Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.
Our exclusive video-led courses are designed to build confidence, knowledge and technique at every stage, working from foundation level to advanced treatments and management of complications.
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