Forehead wrinkles go by several names depending on their location and direction. The horizontal lines that run across your forehead are medically called frontalis rhytids, though they’re commonly known as forehead furrows or worry lines. The vertical lines that form between your eyebrows are called glabellar lines, often nicknamed “elevens” or frown lines. These are distinct types of wrinkles caused by different muscles, and understanding which ones you have helps determine the best way to address them.
Horizontal Forehead Lines
The lines that stretch horizontally across your forehead are caused by the frontalis muscle, a vertically oriented muscle that lifts your eyebrows when you express surprise, interest, or concern. Every time you raise your brows, this muscle contracts and bunches the skin above it into horizontal folds. Over years of repeated use, those temporary creases become permanently etched into the skin.
Not everyone develops these lines in the same pattern. Anatomical studies have found that the frontalis muscle comes in two structural types. In some people, the muscle is continuous across the forehead, producing lines that span the full width. In others, the muscle is thinner or absent in the center, with more developed lateral portions, which creates lines that are more prominent toward the temples. This is why some people get deep creases only on the outer edges of their forehead while others develop them evenly across.
These horizontal lines are commonly called worry lines, surprise lines, or simply forehead lines. In clinical settings, you’ll hear them referred to as horizontal forehead rhytids or frontalis lines.
Vertical Glabellar Lines
The vertical creases that form between your eyebrows sit in an area called the glabella, the patch of skin between your brows and above your nose. These glabellar lines are nicknamed “elevens” because they often appear as two parallel vertical furrows resembling the number 11.
Two muscles are responsible. The corrugator supercilii pulls your eyebrows down and inward (the motion you make when you squint or concentrate), while the procerus muscle pulls the skin between your brows downward (the motion of a deep frown or scowl). Both muscles get heavy use throughout the day, especially if you spend long hours reading, staring at screens, or working in bright light. The result is those stubborn vertical creases that can make your resting expression look angry or tired even when you feel fine.
Dynamic vs. Static: Why the Stage Matters
Forehead wrinkles exist on a spectrum from barely noticeable to deeply grooved, and the clinical distinction that matters most is whether they’re dynamic or static. Dynamic wrinkles appear only when you move your face. Raise your eyebrows and the horizontal lines show up; relax and they disappear. Static wrinkles remain visible even when your face is completely at rest.
You can test this yourself in a mirror. Fully relax your forehead and look closely. Lines that vanish are dynamic, meaning they’re caused purely by muscle movement and the skin still has enough elasticity to bounce back. Lines that stay put are static, meaning the skin itself has lost structural support and the crease has become permanent. Most people start with dynamic lines in their twenties or thirties and gradually see them transition to static lines as collagen and elastin break down with age and sun exposure.
This distinction matters because dynamic and static wrinkles respond to different treatments. Catching lines in the dynamic stage gives you more options for preventing them from becoming permanent.
What Causes Them to Deepen
Repetitive muscle movement is the primary driver, but several factors accelerate how quickly forehead wrinkles appear and deepen. UV exposure is the biggest external contributor: it degrades collagen and elastin fibers in the skin, reducing the scaffolding that keeps skin smooth between expressions. Smoking has a similar effect by restricting blood flow and depleting oxygen in skin tissue.
Genetics also play a significant role. The structure of your frontalis muscle, the thickness of your skin, and how quickly your body produces and breaks down collagen are all inherited traits. Some people develop noticeable forehead lines in their late twenties while others don’t see them until their fifties.
Dehydration, poor sleep, and chronic stress don’t cause wrinkles directly, but they can make existing lines look more pronounced by thinning the skin and reducing its plumpness.
Treatment Options by Wrinkle Type
For dynamic forehead lines, injectable neuromodulators (commonly known by brand names like Botox and Dysport) are the most effective option. These work by temporarily relaxing the muscles responsible for the creases. For horizontal forehead lines, typical doses range from 10 to 30 units, injected across several points on the forehead. Glabellar lines between the brows often require higher doses, up to 40 units, with men generally needing more than women due to stronger muscle mass. Results last roughly three to four months before the muscles gradually regain full movement.
Static wrinkles are harder to treat because the skin itself has changed. Prescription retinoids are the most studied topical option. Clinical trials involving over 1,300 patients have tested concentrations ranging from 0.01% to 0.05%, with treatment periods spanning 16 weeks to two years. These creams work by increasing cell turnover and stimulating collagen production, gradually softening the depth of established lines.
For deeper static lines, energy-based devices like fractional lasers and radiofrequency microneedling treatments can remodel the collagen layer beneath the skin’s surface. These procedures work by creating controlled micro-injuries that trigger the skin’s repair process, resulting in firmer, smoother skin over several months of healing. Multiple sessions are typically needed, and results develop gradually rather than appearing overnight.
Prevention Basics
Daily sunscreen is the single most effective preventive measure. UV damage accounts for the majority of premature skin aging, and consistent broad-spectrum protection slows collagen breakdown significantly. Beyond sun protection, a retinoid product used regularly can help maintain skin thickness and elasticity over time, keeping dynamic lines from transitioning to static ones as quickly.
Wearing sunglasses reduces squinting, which cuts down on both glabellar line formation and crow’s feet. If you notice yourself raising your eyebrows habitually while reading or working at a computer, adjusting your screen height or font size can reduce unnecessary frontalis contractions throughout the day.