Thin lips

Thin lips are lips with little natural volume, a narrow red part (the vermilion) or a poorly defined outline. They are not a health problem: many people are born with them, and with age almost everyone’s lips become thinner. People who want to change them can use make-up, aesthetic medicine treatments such as hyaluronic acid or botulinum toxin and, in specific cases, surgery.

What thin lips are and why they appear

What thin lips look like

Thin lips are recognised by three features that can appear together or separately:

• Little volume: the lips look flat in profile and barely project.
• Narrow vermilion: the red part of the lip, visible with the mouth closed, is short.
• Poorly defined border: the line between lip and skin (the vermilion border) and the Cupid’s bow, the “V” in the centre of the upper lip, are faint.

Lips look “thin” mainly in relation to the rest of the face: lips of the same size can look thin on a wide face and balanced on a narrow one.

Causes of thin lips

Thin lips have two main causes:

• Genetics: the most common cause. Lip fullness is inherited, like the shape of the nose or eyes, and varies widely between people and populations.
• Ageing: over the years the lip loses volume, the vermilion thins and the philtrum (the groove between nose and upper lip) flattens. Behind these changes are the loss of collagen and elastin, less facial fat and changes in the bone and muscles that support the mouth. Thinning of the red lip is considered one of the hallmarks of facial ageing.

Some factors speed up ageing of the skin around the mouth: smoking, unprotected sun exposure and skin dehydration.

Signs that often come with thin lips

When thin lips are due to age, other changes around the mouth usually appear too:

• Vertical lines around the lips, known as smoker’s lines or barcode lines, more marked in smokers.
• Downturned corners of the mouth, which give a sad or tired look.
• A longer upper lip that shows less of the teeth when smiling.

Knowing which change dominates matters, because each one is treated differently.

Options for thin lips

Make-up for thin lips

Make-up is the simplest, fastest and fully reversible way to make thin lips look fuller:

• Line the lips with a pencil in a natural shade, going very slightly over the natural border in the centre (Cupid’s bow and the middle of the lower lip) but not at the corners.
• Use satin or glossy lipsticks in medium or light shades, which reflect light and make the lip look fuller. Matte finishes and very dark shades tend to make it look thinner.
• Add a touch of highlighter on the Cupid’s bow or a little gloss in the centre of the lower lip.
• Keep the lips moisturised: dry, chapped lips look thinner.

Topical treatments

Lip creams and balms improve hydration and texture, which makes lips look fuller, but they do not add real volume. “Plumping” products that slightly irritate the skin to draw blood in work for a few hours only. On the skin around the mouth, retinoids can help soften fine lines over time.

Hyaluronic acid lip filler

Hyaluronic acid filler is the most widely used treatment to add volume and definition to thin lips. It is injected into the body of the lip, the vermilion border or both, depending on whether more volume, more definition or both is wanted. It is the reference material because it integrates well into the tissues and because it is reversible: if the result is not liked or a complication occurs, it can be dissolved with an enzyme, hyaluronidase.

In a meta-analysis of the available studies on hyaluronic acid lip filler, 91% of treated people had fuller lips at 2 months, 74% at 6 months and 46% at one year. In other words, the effect is temporary and is gradually reabsorbed.

The most common side effects in the same analysis were tenderness, swelling and bruising at the injection site, which clear in a few days. Rare complications include granulomas (0.6%), cold sores (0.6%) and angioedema (0.3%). In published complication cases, the most frequent is lumps or nodules; filler migration beyond the lip and discolouration have also been reported. The lips have important arteries close to the surface, so the treatment should always be done by a doctor experienced in the anatomy of the area.

Botulinum toxin lip flip

The lip flip is an alternative to filler that adds no volume. A small dose of botulinum toxin, usually 4 to 6 units, is injected into the muscle around the mouth (the orbicularis oris), just above the upper lip. As the muscle relaxes, the upper lip rolls slightly outwards and more of the red lip shows at rest and when smiling.

According to a systematic review of published studies, results are consistent and satisfaction is high, with little downtime. Side effects are mild and short-lived: for a few weeks it may be harder to whistle or drink through a straw. As with any botulinum toxin treatment, the effect is temporary. The lip flip suits lips with little visible red lip; if volume is what is missing, filler works better, and the two are sometimes combined.

Botulinum toxin around the mouth

Botulinum toxin is also used around thin lips to soften vertical lines on the upper lip and to lift the corners of the mouth when the muscle pulling them down is very active. It does not change the lip itself, but it improves the frame of the mouth, which helps the lips look younger.

Surgery for thin lips

For a permanent result there are surgical options: the lip lift, which shortens the distance between nose and upper lip and shows more vermilion; fat grafting from the person’s own body; and lip implants, which offer a long-lasting result with few complications in expert hands. They are less common than filler and are assessed case by case with a plastic or maxillofacial surgeon.

Frequently asked questions about thin lips

How do I know if I have thin lips?

You have thin lips if the red part of the lips is narrow, if they barely project in profile or if the outline and Cupid’s bow are faint. Rather than an exact measurement, what counts is the proportion with the rest of the face and, above all, whether it bothers you.

Why do lips get thinner with age?

Lips get thinner with age because collagen and elastin are lost, facial fat decreases and the bone and muscles that support them change. Smoking and sun speed up the process. That is why thinning of the red lip is one of the typical signs of facial ageing.

Are thin lips less attractive?

No. What is considered attractive changes with time, culture and the proportions of each face. Thin lips are a normal, harmonious feature on many faces; whether to treat them is a personal decision.

What are the downsides of hyaluronic acid in the lips?

The downsides of hyaluronic acid lip filler are that its effect is temporary (it is reabsorbed over months), that it causes swelling and bruising for the first days and that, uncommonly, it can cause lumps, migration of the product or inflammatory reactions. Serious complications are rare and most can be treated by dissolving the filler with hyaluronidase.

Can lips be made smaller?

Yes, but only with surgery: lip reduction (reduction cheiloplasty) removes part of the lip from inside the mouth, so the scar is not visible. It is the opposite of lip augmentation and is considered for very full or asymmetric lips.

Which is better for thin lips, hyaluronic acid or a lip flip?

It depends on what is missing. If the lips lack volume, hyaluronic acid works better. If the volume is fine but little of the upper red lip shows, a lip flip may be enough. An experienced doctor can judge which is best or whether to combine them.