How Fast Does Letybo Work? Letybo vs. Botox Onset, Peak Results & What to Expect

Letybo can begin working within the first few days after injection. In a Phase III clinical trial of Letybo for moderate-to-severe glabellar lines, the median time to onset was 3 days, with some patients reporting improvement within 24 hours. By Day 3, 74.5% of participants reported at least a one-point improvement in their glabellar-line severity score. However, onset and peak cosmetic results are different, and individual patients may see results at different rates.

At a Glance

How fast does Letybo work?

Median onset: 3 days in a Phase III clinical trial.

Within 24 hours: 24% of participants reported at least a one-point improvement.

By Day 2: 63.9% reported at least a one-point improvement.

By Day 3: 74.5% reported at least a one-point improvement.

Week 1: 82.7% had at least a one-point reduction based on composite in-clinic assessment.

Week 2: 88.0%.

Week 4: 88.7%.

These numbers come from a clinical trial of 355 participants receiving 20 Units of letibotulinumtoxinA or placebo for glabellar lines.

Does that mean Letybo is fully working after 3 days?

No.

Three days represents the median onset, not necessarily the point of maximum cosmetic effect.

Does Letybo work faster than Botox?

Current evidence does not establish that Letybo is universally faster than Botox. One post-hoc analysis of Letybo’s Phase III data reported a median onset of 2.8 days in women aged 35–50 and noted previously published onset estimates for other botulinum toxin products in a similar general range.

Letybo vs. Botox: How Quickly Do They Work?

The American Academy of Dermatology states that most people see results from botulinum toxin within 3–7 days. The Letybo Phase III trial found a median onset of 3 days. However, because these figures come from different evidence sources and definitions, they should not be interpreted as a head-to-head proof that Letybo works faster than Botox.

What Is Letybo?

Letybo is the brand name for letibotulinumtoxinA-wlbg, a botulinum toxin type A product.

The FDA approved Letybo in 2024 for the temporary improvement in the appearance of moderate-to-severe glabellar lines associated with corrugator and/or procerus muscle activity in adults. The FDA-approved glabellar-line regimen is 20 Units divided among five injection sites.

Letybo works by temporarily reducing the nerve signal that causes targeted muscles to contract.

As those muscles become less active, dynamic lines can become less noticeable.

How Soon Does Letybo Start Working?

This is one of the most common questions patients ask after treatment.

The best direct evidence comes from a Phase III randomized, double-blind, placebo-controlled trial.

Researchers had patients record their own results daily for the first two weeks.

The results were:

The study calculated a median onset of 3 days.

This is useful because it shows that Letybo does not necessarily take a week or two before anything happens.

Many patients begin seeing changes within several days.

Can You See Letybo Results After One Day?

Yes, some patients can.

In the Phase III trial, 24% of participants reported at least a one-point improvement within 24 hours.

However, that does not mean 24% of patients had their final cosmetic result after one day.

There is a major difference between:

first detectable improvement

and

maximum cosmetic improvement.

A patient may begin noticing less movement after a day or two while the treatment continues developing.

What Should I Expect From Letybo on Day 1?

During the first day, many patients may notice little or no visible change.

That is completely compatible with the treatment working normally.

Some patients may notice:

• Slightly reduced muscle movement
• Less force when frowning
• Early softening of the “11” lines
• No obvious difference yet

The absence of an immediate dramatic change does not mean the treatment failed.

What Should I Expect From Letybo on Day 2?

By Day 2, more patients in the clinical trial were reporting improvement.

63.9% reported at least a one-point improvement by Day 2.

Patients may begin noticing that the treated muscles don’t contract quite as strongly.

The cosmetic effect may still be subtle.

What Should I Expect From Letybo on Day 3?

Day 3 is particularly important because it was the median onset point in the Phase III trial.

By this point:

74.5% of participants had reported at least a one-point improvement.

That makes approximately three days a reasonable evidence-based benchmark for when many patients can begin noticing a meaningful change.

But again:

Day 3 is not necessarily the final result.

What Should I Expect From Letybo After One Week?

By Week 1, the treatment effect was more apparent.

In the Phase III study, 82.7% of participants had at least a one-point reduction in glabellar-line severity based on composite assessment at Week 1.

This is why patients who are evaluating their result should generally avoid judging the treatment too early.

A result that looks subtle on Day 2 can look considerably different several days later.

When Does Letybo Reach Its Peak Effect?

There is no single universally established “peak day” for every Letybo patient.

This is an important distinction.

The clinical study found high response rates at Weeks 1, 2 and 4, but its design does not justify telling every patient that Letybo reaches its maximum effect on one specific day.

The practical approach is:

Day 0–1

Little or early change.

Days 2–3

Many patients begin noticing an effect.

Days 4–7

The treatment becomes increasingly apparent.

Weeks 1–2

The cosmetic effect is generally much more established.

Week 4

The clinical trial used this as an important efficacy assessment point, and the treatment response was substantial.

How Is “Onset” Different From “Peak Effect”?

These terms should not be used interchangeably.

Onset

Onset means when the treatment first begins producing a measurable effect.

For Letybo, the median onset was 3 days in the Phase III study.

Peak effect

Peak effect means when the treatment has developed its maximum or near-maximum clinical effect.

A patient can therefore have:

Onset on Day 3

without having:

Maximum result on Day 3.

This distinction is one of the most important things patients should understand before evaluating their treatment.

Does Letybo Work Faster Than Botox?

We cannot reliably say that Letybo is faster.

This is an area where online marketing can get ahead of the evidence.

The Letybo Phase III trial found a median onset of 3 days.

The American Academy of Dermatology states that most people see results from botulinum toxin within 3–7 days.

Those findings are compatible with Letybo having a relatively quick onset.

But they do not prove Letybo is faster than Botox.

Why?

Because these are not identical measurements from a randomized Letybo-vs-Botox onset trial.

If you’re deciding between the two products, our detailed guide on whether Letybo is better than Botox examines effectiveness, duration, safety, and other practical differences.

Is There a Head-to-Head Letybo vs. Botox Study?

Yes.

A Phase III randomized controlled trial compared letibotulinum toxin A with onabotulinum toxin A for moderate-to-severe glabellar wrinkles in 500 Chinese participants.

The study was designed to test noninferiority, rather than primarily to prove that one product had a faster onset.

At Week 4, the proportion of participants meeting the study’s efficacy endpoint was 88.49% for letibotulinum toxin A and 87.39% for onabotulinum toxin A. The difference was not statistically significant.

That supports an important conclusion:

Letybo and Botox can both provide effective treatment of glabellar lines, but current evidence does not establish Letybo as universally faster.

Why Do Some People See Letybo Faster Than Others?

There isn’t a single explanation.

Patients differ in:

• Muscle strength
• Facial anatomy
• Baseline wrinkle severity
• Individual response to botulinum toxin
• Injection technique
• Treatment dose
• How they define “seeing results”

The treating clinician’s technique is also important.

The American Academy of Dermatology emphasizes that results depend substantially on the expertise of the person performing the injections.

Does Letybo Work Faster if You Get More Units?

More is not automatically better or faster.

Letybo has an FDA-recommended 20-Unit dose for glabellar lines, divided into five injections.

Treatment should be individualized by the prescribing healthcare professional.

Patients should not assume that receiving additional toxin will automatically produce a faster result.

It is also important to understand that Letybo Units cannot be directly converted into Botox Units. The FDA specifically states that potency units for Letybo are product-specific and are not interchangeable with units from other botulinum toxin products.

Does the Injection Technique Affect How Fast Letybo Works?

The treatment technique matters.

Botulinum toxin is injected into specific muscles at specific locations and doses.

For Letybo’s FDA-approved glabellar treatment, the product is injected into the corrugator and procerus muscles at five specified sites.

Correct:

• Muscle selection
• Injection location
• Dose
• Needle placement
• Product preparation
• Patient assessment

are all important components of treatment.

The FDA labeling specifically provides detailed instructions intended to reduce complications such as eyelid ptosis.

What If I Don’t See Results After 3 Days?

Don’t panic.

Three days is a median onset, not a deadline.

In the clinical trial, some participants had not reported improvement by Day 3.

The study showed increasing response over subsequent days and weeks.

If you see little or no change after several days, it may simply be too early to judge the final result.

If you remain concerned after the expected evaluation period, contact the clinician who performed the treatment.

What If Letybo Hasn’t Worked After One Week?

A week provides more information than the first few days, but individual response still varies.

Possible reasons for a less-than-expected result include:

• The treatment is still developing
• The muscle activity is particularly strong
• The lines are partly static rather than purely dynamic
• The treatment area needs a different strategy
• Individual biological response varies
• The treatment may need clinical reassessment

Do not automatically assume that increasing the dose is the answer.

A qualified injector should evaluate the result.

Why Do Some Wrinkles Remain Even When Letybo Is Working?

Letybo primarily affects dynamic muscle activity.

It does not erase every component of an established wrinkle.

Some lines may remain because they are influenced by:

• Skin quality
• Collagen loss
• Sun damage
• Repeated folding over many years
• Static lines present even when the muscle is relaxed

This is why some patients may benefit from a broader skin-rejuvenation strategy rather than relying on neuromodulator treatment alone.

Can Letybo Make You Look Frozen?

Not necessarily.

The goal of treatment can be to reduce excessive muscle activity while preserving appropriate facial expression.

The American Academy of Dermatology notes that dermatologists aim to use enough botulinum toxin to relax the targeted muscles without unnecessarily affecting other muscles.

The final appearance depends heavily on:

• Anatomy
• Dose
• Injection placement
• Treatment goals
• Injector experience

A natural-looking result is not simply a matter of choosing Letybo versus Botox.

Is Letybo FDA Approved?

Yes.

Letybo received initial U.S. FDA approval in 2024.

The FDA indication is the temporary improvement in the appearance of moderate-to-severe glabellar lines associated with corrugator and/or procerus muscle activity in adults.

The FDA label also makes clear that Letybo is not approved for conditions other than glabellar lines.

What Does the Evidence Actually Tell Us About Letybo’s Speed?

The strongest direct evidence can be summarized very simply:

Letybo starts working within days, not weeks, for many patients.

The Phase III trial found:

• Median onset: 3 days
• 24-hour response: 24.0%
• Day-2 response: 63.9%
• Day-3 response: 74.5%
• Week-1 response: 82.7%
• Week-2 response: 88.0%
• Week-4 response: 88.7%

But these percentages represent the specific outcome definition used in that study and should not be interpreted as a promise that the same percentage of patients at every practice will experience exactly the same response.

Speed is only one part of the decision. If you’re also wondering How long does Letybo last?, our detailed evidence review looks at treatment duration, retreatment timing, and what patients can realistically expect over the following months.

Letybo vs. Botox: What Should You Choose If Speed Matters?

If your primary concern is how quickly your wrinkles will improve, it is reasonable to ask your injector about onset.

But speed should not be the only consideration.

A good treatment decision should consider:

• The treatment area
• Your anatomy
• Your previous response
• Desired degree of movement
• Desired aesthetic result
• Duration
• Cost
• Safety
• Injector experience
• FDA-approved indications

The current evidence does not support choosing Letybo solely because it is supposedly “faster than Botox.”

For the broader evidence-based comparison, see our complete Botox vs. Letybo comparison, which covers the key differences between the two treatments beyond onset alone.

What If I Have an Event Coming Up?

This is an important practical consideration.

If you are planning neuromodulator treatment before:

• A wedding
• Vacation
• Photography
• A major social event
• A professional event

Don’t schedule the treatment immediately beforehand and expect the final appearance the next morning.

Because onset and peak effect are different, giving the treatment adequate time to develop is prudent.

Your clinician can recommend appropriate timing based on your individual circumstances.

Letybo vs. Botox Results Timeline

Day 0

Treatment is administered.

Days 1–2

Some patients begin noticing reduced movement.

Day 3

Median onset in the Phase III Letybo trial.

Days 4–7

The treatment effect becomes increasingly noticeable for many patients.

Week 1–2

The cosmetic effect becomes more established.

Week 4

A major clinical efficacy assessment point.

Later weeks

The effect eventually begins to diminish, with duration varying between individuals.

The onset timeline above is based primarily on the Phase III Letybo study; it should not be interpreted as a guaranteed schedule for every patient.

Evidence vs. Clinical Experience

What the research tells us

The Phase III Letybo study provides direct evidence that:

• Letybo can begin working within days.
• Median onset was 3 days.
• Some participants noticed improvement within 24 hours.
• Response increased through the first several weeks.
• Letybo was effective for glabellar lines.

What may vary in clinical practice

Individual patients can differ in:

• Onset
• Degree of response
• Peak appearance
• Duration
• Patient perception of improvement

What should not be promised

A provider should not guarantee:

“Letybo will work tomorrow.”

or:

“You’ll have your final result in exactly three days.”

The clinical evidence supports a typical range of responses, not an exact schedule for every individual.

Bottom Line: How Fast Does Letybo Work?

Letybo generally begins working within several days.

In its Phase III clinical trial, the median onset was 3 days, with 24% of participants reporting at least a one-point improvement within 24 hours and 74.5% reporting improvement by Day 3. The treatment continued developing beyond the initial onset period.

The American Academy of Dermatology states that most patients receiving botulinum toxin therapy see results within approximately 3–7 days.

The most accurate comparison is therefore:

Letybo works within days, and current evidence does not establish that it is universally faster than Botox.

The quality of the treatment plan and the expertise of the injector are important considerations alongside product selection.

Considering Letybo or Botox in Bethlehem, PA?

If you’re considering Letybo or Botox, the right choice depends on your facial anatomy, treatment goals, previous experience and the specific areas you want to treat.

At Azani Medical Spa in Bethlehem, Pennsylvania, treatment is individualized rather than based solely on which neuromodulator is marketed as the “fastest.”

Dr. Monica Gavin, MD, can evaluate your goals and discuss whether Letybo, Botox or another treatment approach is appropriate for you.

Medical References

U.S. Food and Drug Administration

Letybo (letibotulinumtoxinA-wlbg) Prescribing Information — FDA labeling, indication, dosing, safety and administration.

FDA Letybo Approval Package — initial U.S. approval February 29, 2024.

American Academy of Dermatology

Botulinum Toxin Therapy: Overview — patient information concerning onset and duration of botulinum toxin treatment.

Botulinum Toxin Therapy: FAQs — treatment expectations, safety and repeat treatment.

Peer-Reviewed Literature

Mueller DS, et al. Efficacy and Safety of Letibotulinumtoxin A in the Treatment of Glabellar Lines: A Randomized, Double-Blind, Multicenter, Placebo-Controlled Phase 3 Study. Aesthetic Surgery Journal. 2022;42(6):677–688.

Phase III Noninferiority Trial of Letibotulinum Toxin A vs. Onabotulinum Toxin A. Randomized controlled trial in 500 Chinese participants with moderate-to-severe glabellar wrinkles.

About the Medical Reviewer

Monica Gavin, MD

Dr. Monica Gavin is a physician at Azani Medical Spa in Bethlehem, Pennsylvania. She earned her MD from Wayne State Medical School.

Last medically reviewed: August 2026

Medical content notice: This article is intended for educational purposes and does not replace an individualized medical consultation. FDA labeling and clinical evidence can change. This article should be reviewed periodically when significant new evidence or regulatory changes become available.