Expression lines.
Lines created by repeated muscle movement – frown lines, forehead lines, crow's feet. The domain of botulinum toxin.
Expression lines explained: how they arise from muscle activity, difference to static lines, the mirror test, treatment with botulinum toxin and limits.
A closer look.
Expression (dynamic) lines form where a muscle folds the skin into the same crease for years: when frowning, squinting or smiling. At first they disappear as soon as the muscle relaxes; over time the skin 'remembers' the line because collagen and elastin fatigue at that spot.
The simple test: relax the face completely and look in the mirror. If the line disappears, it is dynamic – here botulinum toxin works by resting the muscle for months. If it stays, it is (also) static and needs volume or skin quality.
Typical dynamic areas are glabella, forehead, crow's feet, bunny lines and the chin crease. Treated early, the dynamic line is prevented from becoming static; that is the core of so-called prevention – sensible only once the line starts to remain at rest.
This lexicon entry is general information and does not replace the medical consultation required under German law (§ 630e BGB).
At a glance.
A question about Expression lines? Send us a short WhatsApp message – we usually reply the same working day.
Ask via WhatsAppFrequently asked questions.
Are expression lines treated with hyaluronic acid?
Usually not; hyaluronic acid is broken down quickly if the muscle keeps working. Botulinum toxin first, then volume if needed.
Do they disappear permanently?
No. Once the effect wears off, movement returns; regular treatment prevents deepening.
Sources and further reading.
- NHS: Botox injections – patient information
- DGBT – German Society for Aesthetic Botulinum Toxin Therapy
- BfArM – Federal Institute for Drugs and Medical Devices
- European Medicines Agency (EMA)
- § 630e BGB – duty to inform before treatment (German Civil Code)
- AWMF – German clinical practice guidelines
External links open in a new window; their operators are responsible for their content. Medical responsibility for this page: Katayoun Mostaghimi, specialist in general medicine. Last updated: 2026-10-05.
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