Short answer
Usually about 3 to 4 months; that figure is best established for frown lines between the eyebrows. The effect begins within a few days, can take a week or more to reach its full extent, then fades gradually as the treated nerve endings recover. How long it lasts for any one person depends on the area treated, the dose, the product and individual variation, and in trials a minority of people still had a clear effect at about 4 months.
Key points
- “Botox” is a brand name for onabotulinumtoxinA, one of several botulinum toxin products.
- Effects usually start in 1 to 3 days; full results can take a week or more.
- The US prescribing information gives about 3 to 4 months for frown lines.
- Repeat injections are spaced at least 3 months apart.
- Doses of different botulinum toxin brands cannot be swapped unit for unit.
Why the effect wears off
Botulinum toxin blocks the nerve signals that tell a muscle to contract3. In cosmetic use, small doses relax the muscles that crease the skin, most commonly for frown lines, forehead creases and crow’s feet4, so lines caused by movement soften. The block is temporary: the nerve ending gradually restores its ability to signal the muscle, and movement returns.
Because recovery is gradual, most people notice movement creeping back over several weeks rather than all at once. Lines that are etched into the skin even at rest may soften less, because they are no longer purely caused by muscle movement.
A typical timeline
| Time after injection | What usually happens |
|---|---|
| 1 to 3 days | Effect begins to show1 |
| About 1 week or more | Full effect can take a week or longer13 |
| About 3 to 4 months | Typical duration for frown lines between the eyebrows2 |
| After 3 months | Earliest usual point for repeat treatment12 |
Mayo Clinic notes that, depending on what is being treated, the effect may last 3 to 4 months, and that not everyone sees a visible result1.
What the trials show
The US prescribing information for Botox Cosmetic states that its duration of effect for glabellar lines (the vertical frown lines between the eyebrows) is approximately 3 to 4 months. In the trials, 25% of treated participants still had no lines or only mild lines at day 120, compared with 2% of those given placebo2. In other words, most people had lost much of the effect by about 4 months, but a meaningful minority had not.
This evidence comes from large randomised placebo-controlled trials, so the typical duration for frown lines is reasonably well established: Strong. Evidence for other facial areas, other brands, and long-term patterns with repeated use is thinner.
What may affect how long it lasts
- Area treated: official sources stress that duration depends on what is being treated1.
- Product and dose: botulinum toxin brands are not equivalent, and their units cannot be converted from one to another23. A comparison of “how long it lasts” between brands is only meaningful at comparable, properly studied doses.
- Individual variation: muscle strength and how a person’s nerves recover differ, which is one reason trial results show a spread rather than a fixed number.
- Antibodies: because botulinum toxin is a protein, the body can in principle develop antibodies to it. In three trials of crow’s feet treatment, 1.5% of 916 participants developed binding antibodies and none developed neutralising antibodies (the type that can block the effect)2.
Claims that results “last longer and longer” with regular treatment are common, but there is little high-quality evidence for this: Insufficient.
How often it is repeated
Mayo Clinic advises follow-up injections spaced at least 3 months apart1, and the prescribing information notes that dosing more often than every 3 months has not been clinically evaluated2. MedlinePlus similarly describes further injections every 3 to 4 months, depending on the condition3. Topping up sooner adds exposure without evidence that it is safe or useful.
When to seek medical advice
The effect of any botulinum toxin product can spread beyond the injection site, with symptoms appearing hours to weeks later2. Contact a clinician straight away, or seek emergency care, for muscle weakness, vision problems, trouble speaking or swallowing, or breathing difficulty13.
Common questions
Does Botox last longer the more often you have it?
Not reliably; this is widely claimed but not well supported by controlled studies. Treatment is not recommended more often than every 3 months2.
Why did my Botox wear off after a few weeks?
An unusually short effect may reflect the dose, the product, the area or individual response; not everyone gets a visible result1. It is worth discussing with the treating clinician rather than seeking extra injections elsewhere, since brand units are not interchangeable3.
Are some botulinum toxin brands longer-lasting?
Possibly, but brand claims need care: products are not equivalent and their units cannot be converted2, so any claim of longer duration should rest on published trial data at properly studied doses rather than on marketing.
Should I rub the area to make it work faster?
No; Mayo Clinic advises not rubbing or massaging treated areas for 24 hours to reduce the chance of the toxin spreading1.
Bottom line
For frown lines, the well-studied figure is about 3 to 4 months, with some people holding the effect longer. Area, product, dose and individual biology shift that figure, and repeat treatment is not advised sooner than every 3 months.
Related reading
- Botulinum toxin (anti-wrinkle injections)
- Why Can Botox Cause a Droopy Eyelid, and What Happens Next?
- How Can You Tell Whether Botox Is Genuine?
- Is There a Right Age to Start Anti-Wrinkle Injections?
Sources
- Mayo Clinic. Botox injections. Mayo Clinic. https://www.mayoclinic.org/tests-procedures/botox/about/pac-20384658. Accessed 5 November 2026.
- US National Library of Medicine. BOTOX Cosmetic (onabotulinumtoxinA) prescribing information, revised October 2024. DailyMed; 2024. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=485d9b71-6881-42c5-a620-a4360c7192ab. Accessed 5 November 2026.
- MedlinePlus. OnabotulinumtoxinA injection. US National Library of Medicine. https://medlineplus.gov/druginfo/meds/a608013.html. Accessed 5 November 2026.
- American Society of Plastic Surgeons. Botulinum toxin. ASPS. https://www.plasticsurgery.org/cosmetic-procedures/botulinum-toxin. Accessed 5 November 2026.
Article history
- — First published.