Frown Lines Between the Brows: Causes and Treatment

The vertical lines between your eyebrows, often called the "11s", are caused mainly by two small muscles that pull the brows together and down when you frown, squint or concentrate. A neuromodulator injected into those muscles is the most common medical treatment, and it typically softens the lines over one to two weeks. When the lines have become deeply etched into the skin, other treatments may be added.

The muscles behind the "11s"

The area between the brows is called the glabella. Two muscle groups do most of the work here:

• The corrugators sit just above the inner part of each eyebrow. When they contract, they pull the brows inward and slightly down, creating vertical lines.
• The procerus is a small muscle at the top of the nose, between the brows. It pulls the skin downward and can create a horizontal line across the bridge of the nose.

The strength and shape of these muscles vary a great deal. Some people form a single deep line, some form two parallel lines, and others form a pattern of several smaller creases. Looking closely at your own frown pattern is the starting point for planning treatment.

Why the lines deepen over time

We frown far more often than we realise. Reading small print, squinting into bright sun or glare off the snow, focusing on a screen, or simply worrying can all activate these muscles. Over years, the skin folds in the same place thousands of times.

Gradually, collagen and elastic fibres in the skin weaken, especially with cumulative sun exposure and smoking. The fold that once vanished at rest begins to leave a permanent mark. Many people also find that frown lines make them look tired, cross or stressed when they feel perfectly calm, which is a common reason they seek advice.

It is worth checking some everyday contributors too. Uncorrected vision, not wearing sunglasses, and long hours at a screen can all increase squinting. Addressing those habits does not erase existing lines, but it may reduce the strain on the area.

How neuromodulator treatment works here

A neuromodulator, such as botulinum toxin type A, blocks the nerve signal that tells a muscle to contract. When placed into the corrugator and procerus muscles, it weakens the frowning action so the skin is no longer folded as forcefully. For a full explanation of the mechanism, see our article on what a neuromodulator is and how it works.

The frown area is one of the most studied uses of cosmetic neuromodulators. Treatment usually involves a small number of injection points, commonly in the centre and along each inner brow. The exact pattern depends on where your muscles are strongest and how far they extend toward the outer brow.

Relaxing these brow-lowering muscles can also allow the inner brows to sit slightly higher or look more open. This effect is subtle and varies from person to person.

Onset and how long it lasts

Most people begin to see their frown soften between 3 and 7 days after treatment, with the full effect by around 14 days. A follow-up at about two weeks allows the result to be checked and any uneven areas noted.

Results commonly last three to four months. Because the frown muscles can be quite strong, especially in men and in people who frown heavily, some find that movement returns a little sooner. Repeated treatment over time may help etched lines look softer, since the skin is folded less often.

When filler might be added for etched lines

A neuromodulator reduces movement, but it cannot fill a groove that has already formed in the skin. If you still see a line when your face is completely relaxed, it is a static line. For some people, a very small amount of a soft hyaluronic acid filler can be placed carefully to soften that groove once the muscle has been relaxed.

This needs a cautious approach. The area between the brows contains small blood vessels that connect to the vessels around the eye. Filler placed in this region carries a real, though uncommon, risk of blocking a blood vessel, which can damage skin and, very rarely, affect vision. For this reason, many physicians try neuromodulator first, consider skin-quality treatments such as laser, and use filler here only when it is clearly appropriate. Our article on vascular occlusion and filler safety explains why this matters.

Who should avoid or delay treatment

Treatment is not recommended if you are pregnant or breastfeeding, have a condition affecting nerves and muscles such as myasthenia gravis, have had a previous allergic reaction to a botulinum toxin product, or have an infection or inflamed skin in the area. Some medications, including certain antibiotics, can interact with neuromodulators, so bring a complete medication list. If you take a blood thinner, keep taking it as prescribed and tell your physician, who can discuss bruising risk with you.

People with a heavy upper eyelid or droopy brows need careful assessment, because treatment in nearby areas can sometimes make this more noticeable.

Side effects and risks

The most common effects are mild: redness, small bumps for a short while after injection, tenderness, bruising and occasionally a headache. Less often, the product may spread to a nearby muscle and cause a temporary droop of the upper eyelid. This usually appears within the first two weeks and resolves gradually as the medicine wears off, typically within a few weeks. Brow asymmetry can also occur.

Serious reactions are rare. Contact a doctor right away if you develop trouble with your vision, swallowing, speaking or breathing.

Frequently asked questions

Will treatment stop me from looking angry?

Softening the frown muscles can reduce the appearance of a stern or tense expression at rest. It does not change your personality or your feelings, and you can still show concern and other emotions with the rest of your face.

Can frown lines be treated without needles?

Daily sunscreen, sunglasses, a retinoid at night and good eye care can help skin quality and reduce squinting. These will not relax the muscle, but for mild lines they may be all some people want.

Is the frown area treated differently in men?

Men often have stronger frown muscles and may need a different dosing plan. The approach is always based on the individual's assessment rather than a fixed formula.

If the lines between your brows have become a concern, you are welcome to arrange a consultation at HealthPark Medical Aesthetics. A physician will look at your frown pattern, your skin and your health history, then explain the options that make sense for you, including whether no treatment is the better choice.