In short. Botulinum toxin for facial wrinkles temporarily reduces the muscle activity that folds the skin, softening expression lines on the forehead, between the brows and at the outer corners of the eyes. It does not fill or resurface the skin, and it usually lasts about three to six months.

Key points

  • It works on lines driven by muscle movement, not on volume loss or surface texture.
  • Full effect develops over about one to two weeks and usually lasts three to six months.
  • Static creases may soften gradually, but deep long-standing lines often need combination treatment.
  • Spread to neighbouring muscles can cause a heavy brow or droopy eyelid, usually temporarily.
  • Maintenance is roughly every three to six months, and intervals can sometimes lengthen.

Which wrinkles respond to treatment?

Botulinum toxin is the most widely used injectable treatment for expression lines, the wrinkles that form where repeated facial movement creases the skin: the forehead, between the brows, and at the outer corners of the eyes. Not every wrinkle is an expression line. Dynamic lines appear with movement and fade at rest; static lines remain visible even when the face is relaxed, because the skin itself has lost elasticity and thickness. Botulinum toxin works on the muscle-driven component. Static lines may soften gradually once the skin stops being repeatedly folded, but deep, long-standing creases often need combination treatment, such as skin quality work, resurfacing, or fillers, and may never disappear entirely.

How the toxin reduces muscle activity

Botulinum toxin temporarily interrupts the chemical signal that tells a muscle to contract. Injected in small, precisely placed amounts, it reduces the strength of targeted muscles while leaving enough activity for natural expression when planned well. The effect develops over several days to two weeks and typically lasts about three to six months, after which muscle activity and lines gradually return unless treatment is repeated. By reducing repeated folding, it gives existing lines a chance to soften and slows the formation of new ones.

Who is a suitable candidate?

The best candidates have lines driven mainly by muscle movement, with reasonable skin quality and realistic goals. People whose concern is volume loss, sagging, or surface texture may be better served by fillers, energy-based devices, or surgical options such as a brow lift for heavy upper-face descent. A qualified medical consultation and facial assessment should always precede treatment, because the right answer is sometimes not an injection at all.

Concern What the toxin does What it does not do What may suit instead
Dynamic expression lines Reduces the muscle activity that folds the skin Fill or resurface the skin Nothing; toxin is the treatment
Static lines May soften them gradually once the skin is folded less often Remove a crease outright Combination treatment if the line is deep
Volume loss No direct effect Restore volume Fillers
Sagging No direct effect Lift the tissue Energy-based devices or surgery
Surface texture No direct effect Resurface the skin Skin-quality work or resurfacing
Heavy upper-face descent No direct effect Reposition the brow Surgical options such as a brow lift

Why the first treatment is conservative

Assessment maps which muscles pull, how strongly, and how symmetrically. A first treatment uses conservative doses at carefully chosen points, with the aim of softening movement rather than freezing the face. A review two to three weeks later evaluates the response before any top-up. Over subsequent sessions the plan is individualised to that person's muscle pattern, aiming for the smallest effective dose at the longest comfortable interval.

What happens during and after the injections

The injections take minutes, with mild brief discomfort and no real downtime. Small bumps at injection points settle within an hour or two; bruising, when it happens, fades over days. Patients are usually advised not to rub the area, lie flat, or exercise strenuously for the rest of the day. The smoothing effect builds over about one to two weeks.

The side effect that matters most

Common effects are temporary: tenderness, small bruises, or a headache in the first day or two. The effect that matters most is spread to neighbouring muscles, a heavy or droopy brow or eyelid after forehead treatment for example, which is uncommon, temporary, and strongly related to placement, dose, and individual anatomy. Choosing a qualified medical practitioner with detailed facial anatomy training is the main safety decision.

How maintenance is planned

Because results are temporary and variable between individuals, maintenance sessions roughly every three to six months sustain the effect. Many people find lines soften progressively with regular treatment as the skin is folded less often, and intervals can sometimes lengthen over time.

When to seek medical review

An eyelid or brow that droops noticeably after treatment, or double or blurred vision, needs prompt assessment even though these usually resolve. Treatment should be deferred or avoided in pregnancy, breastfeeding, or a neuromuscular condition such as myasthenia gravis. Wrinkles accompanied by facial asymmetry at rest or new weakness need neurological evaluation, not cosmetic treatment.

Sources

Internal links

Frequently asked questions

How long does botulinum toxin last on facial wrinkles?

Muscle activity and lines gradually return over about three to six months, which is why maintenance sessions are usually planned at that interval. Results vary between individuals, and with regular treatment some people find the effect lasts a little longer and lines soften progressively.

Can botulinum toxin remove deep wrinkles that show at rest?

Only partly. Toxin works on the muscle-driven component of a line. Static creases etched into the skin may soften gradually once the skin is folded less often, but deep long-standing lines often need combination treatment and may never disappear entirely.

Who should not have this treatment?

People who are pregnant or breastfeeding, or who have a neuromuscular condition such as myasthenia gravis, should defer or avoid treatment. Anyone whose concern is volume loss, sagging or surface texture is usually better served by a different approach.

Risks & Limitations

  • Vascular occlusion — a time-critical emergency in which filler blocks a blood vessel. It can cause skin loss and, rarely, blindness.
  • Nodules, lumps or granuloma formation, which may need treatment or dissolution.
  • Infection at the injection site.
  • Asymmetry or over-correction; over-treatment is harder to correct than under-treatment.
  • Migration of filler away from the intended area.
  • Temporary brow or eyelid droop after botulinum toxin, which resolves as the effect wears off.
  • Bruising and swelling. All injectable results are temporary and maintenance is required.

When to Seek Care

  • Severe pain out of proportion to the procedure, or skin turning white, grey, mottled or dusky — this is a vascular emergency; seek care immediately.
  • Any change in vision — seek emergency care immediately.
  • Fever, spreading redness, warmth or pus at an injection site.
  • A hard, painful lump that is growing.
  • Drooping eyelid, difficulty swallowing, or difficulty breathing after botulinum toxin.

References & Further Reading

  • American Academy of Dermatology (AAD) — injectable safety information
  • American Society of Plastic Surgeons (ASPS) — injectable guidance
  • U.S. Food and Drug Administration (FDA) — approved filler and neurotoxin products
  • National Medical Products Administration (NMPA, China) — approved product status

Medically reviewed by Ke He, MD (何锞), Deputy Director & Head of Skin & Laser Aesthetics. Last reviewed: 18 September 2026.

This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.