Quick answer
Expression lines (forehead, frown lines and crow’s feet) are caused by repeated muscle contraction. The most common treatment is botulinum toxin, a prescription-only medicine applied by the doctor in small doses. The effect shows within a few days and lasts a few months, to a variable degree.
Why they appear
Every time we frown, squint or raise our eyebrows, the muscles fold the skin. Over the years, and with collagen loss, these lines become visible even at rest.
How the treatment works
The doctor identifies the muscles involved and injects botulinum toxin at precise points. The aim is to soften the lines while keeping natural expression. For lines already visible at rest, combining with hyaluronic acid or a collagen biostimulator may help.
Want to know if it suits you? See our Expression line treatment page or book an assessment.
How the session works
Assessment of your expression in motion, skin cleansing and injection with a very fine needle. It takes about 15 to 20 minutes and you can usually return to your routine straight away.
Aftercare and possible side effects
For the first few hours avoid lying down, massaging the area and intense exercise. Small bruises, a mild headache or, rarely, a temporary drooping of the eyelid or eyebrow may occur. Contraindications include pregnancy, breastfeeding and some neuromuscular conditions.
Frequently asked questions
When will I see the effect?
It starts within a few days and settles at around two weeks.
How long does it last?
A few months, to a variable degree. The doctor advises when to repeat.
Will I lose my expression?
The aim is to soften the lines while keeping your expression. The dose is adjusted at the assessment.
How is it different from hyaluronic acid?
See our article botulinum toxin or hyaluronic acid.
Take the first step with an assessment
At the consultation, the doctor examines you, explains the options and tells you clearly what is and is not suitable in your case.
Reference sources: Infarmed — Medicines information (SmPC and leaflet) · American Academy of Dermatology · NHS — Cosmetic procedures
Informational content prepared by the Mya Clínica team. It does not replace a medical consultation. Results vary from person to person and are not guaranteed. Mya Clínica · CÉLULA ÁUREA – UNIPESSOAL LDA · ERS registration E178305, E178306, E178307 · Operating licence no. 26007/2025.
