Letybo (Botulinum Toxin Type A)
Injectable treatment for moderate to severe glabellar frown lines
Quick facts about Letybo
Key takeaways about Letybo
- Specialist administration required: Letybo must only be administered by a qualified physician with appropriate expertise and equipment; it is not a self-injection medicine
- Units are not interchangeable: Letybo units are specific to this product and cannot be compared to or substituted with units of other botulinum toxin preparations such as Botox, Dysport, or Xeomin
- Temporary effects: Results typically last 3 to 4 months; a minimum interval of 3 months between treatments is recommended for safety
- Serious risks are rare but possible: Botulinum toxin can spread beyond the injection site in very rare cases, causing difficulty swallowing, breathing, or speaking — seek immediate medical attention if these occur
- Not for everyone: Letybo should not be used during pregnancy or breastfeeding, in people with neuromuscular diseases, or in those under 18 or over 75 years of age
What Is Letybo and What Is It Used For?
Letybo contains botulinum toxin type A, a neuromuscular blocking agent that temporarily paralyzes the muscles responsible for frown lines between the eyebrows. It is approved for adults under 75 years to improve moderate to severe glabellar lines when they have significant psychological impact.
Letybo is a prescription medicine that contains the active substance botulinum toxin type A, produced by the bacterium Clostridium botulinum. It belongs to a class of medications known as neuromuscular blocking agents. The drug works by blocking the transmission of nerve impulses to the muscles at the injection site, which prevents the muscles from contracting. This leads to temporary, controlled muscle relaxation that smooths out wrinkles in the treated area.
The primary approved indication for Letybo is the temporary improvement of the appearance of moderate to severe vertical frown lines between the eyebrows (known medically as glabellar lines or colloquially as "frown lines" or "eleven lines"). These lines form due to repeated contraction of the corrugator supercilii and procerus muscles during facial expressions such as frowning, squinting, or concentrating. Over time, these dynamic lines can become static, meaning they are visible even when the face is at rest.
Letybo is indicated only when the severity of the glabellar lines has a significant psychological impact on the patient. This is an important distinction, as the treatment is not purely cosmetic in a superficial sense — it is intended for patients who experience genuine distress or impaired quality of life due to the appearance of their frown lines. Clinical trials supporting the approval of Letybo demonstrated statistically significant improvement in glabellar line severity compared to placebo, with effects typically becoming apparent within 2 to 3 days after injection and reaching peak effect at approximately 2 weeks.
Botulinum toxin type A is available under several different brand names worldwide, including Botox (onabotulinumtoxinA), Dysport (abobotulinumtoxinA), Xeomin (incobotulinumtoxinA), and Letybo (letibotulinumtoxinA). Although all contain botulinum toxin type A, they are distinct products with different formulations, potencies, and dosing units. Units of one product cannot be converted to or substituted with units of another product.
How does Letybo work?
Botulinum toxin type A exerts its therapeutic effect by interfering with the process of neuromuscular transmission. Under normal circumstances, when a nerve impulse reaches the nerve ending at a neuromuscular junction, the neurotransmitter acetylcholine is released from vesicles within the nerve terminal. This acetylcholine crosses the synaptic cleft and binds to receptors on the muscle fiber, triggering muscle contraction.
Letybo works by cleaving a specific protein (SNAP-25) that is essential for the fusion of acetylcholine-containing vesicles with the nerve terminal membrane. By preventing this fusion, the toxin effectively blocks the release of acetylcholine, which in turn prevents the muscle from receiving the signal to contract. The result is a temporary, localized paralysis of the injected muscle.
Over a period of several months, the nerve terminal regenerates new connections and the muscle gradually regains its ability to contract. This is why the effects of Letybo are temporary and repeat treatments are needed to maintain the cosmetic improvement.
What Should You Know Before Taking Letybo?
Letybo must not be used in patients with neuromuscular diseases (such as myasthenia gravis or ALS), active infection at the injection site, or known allergy to botulinum toxin. Special caution is needed in patients with swallowing or breathing difficulties, bleeding disorders, or those taking certain antibiotics.
Before receiving Letybo, a thorough medical evaluation is essential. Your treating physician will review your medical history, current medications, and any previous experience with botulinum toxin products. This assessment is critical because certain conditions and medications can significantly alter the safety and effectiveness of the treatment. Being open and honest with your healthcare provider about your health status is the foundation for a safe treatment experience.
Contraindications
Letybo must not be used if you have any of the following conditions:
- Allergy to botulinum toxin type A or any other ingredient in the product (including human albumin and sodium chloride)
- Neuromuscular diseases such as myasthenia gravis, Lambert-Eaton myasthenic syndrome, or amyotrophic lateral sclerosis (ALS) — these conditions affect the nerve-muscle connection and can be dangerously worsened by botulinum toxin
- Active infection or inflammation at the proposed injection site, as injecting into inflamed or infected tissue increases the risk of complications and may alter the distribution of the toxin
Warnings and Precautions
Speak with your doctor before receiving Letybo if you have any of the following conditions or situations, as additional monitoring or dose adjustments may be necessary:
- Any disease affecting muscles or their nervous system control, even if not formally diagnosed as one of the contraindicated conditions
- Previous swallowing or breathing difficulties, including any history of aspiration pneumonia, as botulinum toxin effects could potentially worsen these problems
- Bleeding disorders or current anticoagulant therapy, as the injection procedure involves multiple needle punctures that carry a risk of bruising or bleeding
- History of previous botulinum toxin treatment, particularly if side effects occurred, or if the previous treatment was with a different product, as antibodies may have developed
- Difficulty swallowing, speaking, or breathing after treatment
- Double vision or severely drooping eyelids
- Excessive or unexpected muscle weakness
- Signs of allergic reaction: swelling of face, lips, mouth, or throat; difficulty breathing; hives
These symptoms may indicate toxin spread beyond the injection site or a serious allergic reaction, both of which require urgent medical care.
Pregnancy and Breastfeeding
Letybo is not recommended during pregnancy or breastfeeding. If you are of childbearing age, you should use effective contraception during treatment. There are no adequate and well-controlled studies of botulinum toxin in pregnant women, and animal studies have shown reproductive toxicity at high doses. The potential risk to the developing fetus is unknown but cannot be excluded.
It is also not known whether botulinum toxin type A or its metabolites are excreted in human breast milk. As a precautionary measure, breastfeeding should be avoided during treatment with Letybo. If you are planning to become pregnant, discuss the timing of treatment with your physician.
Children and Adolescents
Letybo has not been studied in patients under 18 years of age and is not recommended for use in children or adolescents. The safety and efficacy of Letybo in the pediatric population have not been established for any indication.
Driving and Operating Machinery
Botulinum toxin type A may cause weakness, dizziness, and visual disturbances in some patients. If you experience any of these effects after treatment, you should not drive or operate machinery until the symptoms have resolved. It is your responsibility to assess whether you are fit to drive or perform tasks requiring alertness, taking into account the potential effects and side effects described in this information.
Sodium Content
Letybo contains less than 1 mmol (23 mg) of sodium per dose and is therefore considered essentially sodium-free. This is relevant for patients on sodium-restricted diets.
How Does Letybo Interact with Other Drugs?
Letybo can interact with aminoglycoside antibiotics, spectinomycin, neuromuscular blocking agents, and other botulinum toxin products. These interactions may enhance the neuromuscular blocking effect, potentially leading to excessive muscle weakness. Always inform your doctor of all medications you are taking.
Drug interactions with Letybo are clinically significant because they can potentiate the neuromuscular blocking effect of botulinum toxin, leading to excessive or prolonged muscle weakness. It is essential that you provide your treating physician with a complete list of all medications you are currently taking, have recently taken, or might take in the future. This includes prescription medicines, over-the-counter products, herbal supplements, and vitamins.
| Drug / Drug Class | Type of Interaction | Clinical Effect | Recommendation |
|---|---|---|---|
| Aminoglycoside antibiotics (gentamicin, tobramycin, amikacin) | Pharmacodynamic | Enhanced neuromuscular blockade; increased risk of excessive muscle weakness | Use with extreme caution; monitor closely for signs of weakness |
| Spectinomycin | Pharmacodynamic | Potentiation of neuromuscular blocking effect | Avoid concurrent use if possible |
| Other botulinum toxin products (Botox, Dysport, Xeomin) | Additive | Cumulative neuromuscular blockade; risk of severe systemic weakness | Do not use concurrently or until effects of previous injection have fully resolved |
| Neuromuscular junction blocking agents (e.g., tubocurarine) | Pharmacodynamic | Synergistic effect on muscle paralysis | Use with caution; inform anesthesiologist before surgery |
| Muscle relaxants (baclofen, tizanidine) | Additive | May increase muscle relaxation effect | Monitor for excessive weakness |
Major Interactions
The most clinically significant interactions involve medications that themselves affect neuromuscular transmission. Aminoglycoside antibiotics (such as gentamicin, tobramycin, and amikacin) are known to have intrinsic neuromuscular blocking properties and can substantially potentiate the effect of botulinum toxin. If you require treatment with an aminoglycoside antibiotic while the effects of Letybo are still active, your healthcare provider should monitor you closely for any signs of excessive muscle weakness, including difficulty swallowing or breathing.
Other botulinum toxin preparations represent another critical interaction. Administering a second botulinum toxin product while the effects of a previous injection have not yet resolved can lead to dangerous cumulative neuromuscular blockade. There should always be an adequate washout period between treatments with different botulinum toxin products, and patients should never seek additional treatments from other providers without disclosing their treatment history.
Minor Interactions
While less clinically significant, certain other medications may theoretically interact with Letybo. Muscle relaxants such as baclofen or tizanidine may have an additive effect on muscle weakness, though this is generally of limited concern when botulinum toxin is used for cosmetic purposes in the glabellar region. Anticoagulants and antiplatelet agents (such as warfarin, aspirin, or clopidogrel) do not directly interact with the pharmacological action of botulinum toxin, but they increase the risk of bruising at the injection site.
If you are scheduled for surgery requiring general anesthesia, inform your anesthesiologist that you have received a botulinum toxin injection, as certain anesthetic agents (particularly neuromuscular blocking agents used during surgery) may have an enhanced effect.
What Is the Correct Dosage of Letybo?
The recommended dose of Letybo for glabellar lines is 20 units, divided into 5 intramuscular injections of 4 units (0.1 mL) each. The treatment must be administered by a qualified physician. A minimum interval of 3 months between treatments is recommended.
Letybo is not a self-administration medicine. It must be reconstituted and injected by a qualified healthcare professional with appropriate training in the use of botulinum toxin and familiarity with facial anatomy. The precise placement of injections is critical to both the safety and efficacy of the treatment.
Adults (18-74 years)
Standard Dosing Protocol
The recommended dose is 20 units, divided into 5 intramuscular injections of 0.1 mL each (4 units per injection site):
- 2 injections in each corrugator supercilii muscle (the muscles above each eyebrow that pull the brows together)
- 1 injection in the procerus muscle (the muscle at the bridge of the nose between the brows)
Each vial of Letybo (50 units) is reconstituted with 1.25 mL of sterile 0.9% sodium chloride solution. After reconstitution, each 0.1 mL contains 4 units of botulinum toxin type A.
| Injection Site | Number of Injections | Dose per Injection | Total Dose |
|---|---|---|---|
| Right corrugator supercilii | 2 | 4 units (0.1 mL) | 8 units |
| Left corrugator supercilii | 2 | 4 units (0.1 mL) | 8 units |
| Procerus | 1 | 4 units (0.1 mL) | 4 units |
| Total | 5 | 4 units each | 20 units |
Children
Letybo is not approved for use in children or adolescents under 18 years of age. No clinical data are available for this population, and the safety and efficacy have not been established. Botulinum toxin should never be administered to minors for cosmetic purposes.
Elderly (Over 75 years)
The clinical studies for Letybo's approved indication (glabellar lines) included patients up to 75 years of age. There is limited data on the use of Letybo in patients over 75 years, and it is not recommended for use in this age group for the approved cosmetic indication.
Treatment Interval
It is recommended that at least 3 months should elapse between two treatments with Letybo. This interval is based on the typical duration of the drug's effect and is important for safety reasons. More frequent injections increase the risk of developing neutralizing antibodies against botulinum toxin, which could reduce the effectiveness of future treatments.
Overdose
Overdose with botulinum toxin can cause paralysis of muscles and nerves beyond the intended injection site. Signs and symptoms of overdose may not appear immediately after injection but can develop over hours to days. Symptoms may include:
- Generalized weakness or muscle paralysis
- Drooping of the upper eyelids (ptosis) or double vision
- Difficulty swallowing (dysphagia) or speaking (dysarthria)
- Partial paralysis of the respiratory muscles, potentially leading to breathing difficulty
Seek immediate medical attention. The patient should be monitored in a hospital setting and may require respiratory support. Botulinum toxin antitoxin may be considered in severe cases, though its efficacy after symptoms have developed may be limited. Find your emergency number →
What Are the Side Effects of Letybo?
The most common side effects of Letybo are headache and injection site reactions. Less common effects include eyelid drooping (ptosis), eyelid spasms, and bruising around the eyes. Most side effects are mild to moderate, appear within the first few days, and are temporary. Serious side effects such as difficulty swallowing or breathing are very rare.
Like all medicines, Letybo can cause side effects, although not everyone experiences them. The majority of reported side effects are mild to moderate in severity, typically occur within the first few days after injection, and resolve spontaneously without additional treatment. The risk and nature of side effects are influenced by factors including injection technique, the dose administered, individual patient anatomy, and any underlying medical conditions.
It is important to distinguish between expected, transient effects of the treatment (such as mild redness or swelling at injection sites) and side effects that may warrant medical attention. The following classification uses standard frequency categories based on clinical trial data and post-marketing surveillance.
Common
- Headache
- Injection site reactions (redness, swelling, tenderness)
Uncommon
- Drooping of the upper eyelid (ptosis)
- Eyelid spasms (blepharospasm)
- Local swelling (eyelid, face, around eyes)
- Injection site: pain, bruising, swelling, itching, hardening, pressure
- Bruising around the eyes (periorbital hematoma)
- Upper respiratory tract infection (e.g., common cold)
- Elevation of the outer eyebrows (Mephisto sign)
- General discomfort
Rare
- Reduced sensation in the eyelid
- Drooping eyebrow
- Bleeding in the conjunctiva (subconjunctival hemorrhage)
- Eye pain, dry eyes, visual field disturbances, blurred vision
- Reduced sensation in the throat
- Constipation
- Voice changes (dysphonia)
- Migraine, dizziness
- Abnormal sensations (tingling, crawling, itching)
- Nausea
- Dry skin, hives (urticaria), itching (pruritus)
- Facial pain, fever
- Inflammation of hair follicles (folliculitis)
- Cold sores (oral herpes)
- Elevated potassium levels (hyperkalemia)
- Influenza-like illness
Very Rare
- Muscle weakness (distant from injection site)
- Difficulty swallowing (dysphagia)
- Aspiration pneumonia (infection from inhaling food or liquid)
- Difficulty breathing (respiratory compromise)
Serious Side Effects Requiring Immediate Attention
While extremely rare, the most serious potential complication of any botulinum toxin treatment is the distant spread of the toxin effect. This occurs when the botulinum toxin migrates beyond the intended injection site to affect muscles elsewhere in the body. Symptoms can include generalized weakness, double vision or blurred vision, drooping eyelids, voice changes, difficulty articulating words, difficulty swallowing, and difficulty breathing.
Swallowing and breathing difficulties are medical emergencies and can be life-threatening. If you develop any difficulty swallowing, speaking, or breathing after receiving Letybo, seek emergency medical care immediately.
A severe allergic reaction (anaphylaxis) to botulinum toxin is also possible, though extremely rare. Signs include sudden onset of difficulty breathing, swelling of the face, lips, mouth, or throat, widespread hives, and a drop in blood pressure. This requires immediate emergency treatment.
Pain associated with injections and/or fear of needles can lead to a vasovagal response (fainting) due to a sudden drop in blood pressure. If you have a history of needle phobia or fainting during medical procedures, inform your healthcare provider so that appropriate precautions can be taken, such as having you lie down during the procedure.
How Should You Store Letybo?
Unopened Letybo must be stored and transported refrigerated at 2-8°C (36-46°F). After reconstitution, the solution should be used immediately or within 24 hours if stored at 2-8°C. Keep out of the reach and sight of children.
Proper storage of Letybo is critical to maintaining the potency and safety of the product. Botulinum toxin is a biological product that can lose its effectiveness if exposed to inappropriate temperatures or handling conditions. While patients typically do not handle or store Letybo themselves (as it is administered in a clinical setting), understanding the storage requirements provides context for the overall safety profile of the treatment.
Storage Before Reconstitution
- Temperature: Store and transport at 2°C to 8°C (36°F to 46°F)
- Light: Store in the original packaging to protect from light
- Freezing: Do not freeze
- Expiry: Do not use after the expiration date printed on the label and carton (EXP). The expiration date refers to the last day of that month
Storage After Reconstitution
Once Letybo has been reconstituted (dissolved in sterile saline), the chemical and physical stability of the solution has been demonstrated for 24 hours at 2-8°C. However, from a microbiological perspective, the product should ideally be used immediately after reconstitution. If not used immediately, the healthcare professional is responsible for the in-use storage conditions.
Any reconstituted solution that has been stored for more than 24 hours must be discarded. The reconstituted vial should only be used for a single treatment session in a single patient. Any remaining solution must be properly disposed of and must not be saved for later use.
Disposal
Due to the nature of botulinum toxin, specific disposal procedures are required. Unused Letybo should be reconstituted with a small amount of water and then autoclaved. Alternatively, it can be inactivated with dilute sodium hydroxide solution (0.1 N NaOH) or dilute sodium hypochlorite solution (0.5% or 1% NaOCl). All used vials, syringes, and materials must be disposed of in appropriate sharps containers and handled in accordance with local regulations for biological and medical waste.
What Does Letybo Contain?
Each vial of Letybo contains 50 units of botulinum toxin type A (produced from Clostridium botulinum) as the active substance. Inactive ingredients include human albumin and sodium chloride. After reconstitution with 1.25 mL saline, each 0.1 mL contains 4 units.
Understanding the composition of Letybo is important for identifying potential allergens and for healthcare professionals preparing the product. The formulation is designed to maintain the stability and biological activity of the botulinum toxin during storage and after reconstitution.
Active Ingredient
The active substance is botulinum toxin type A, produced by the bacterium Clostridium botulinum. Each glass vial contains 50 units of the toxin. After reconstitution with 1.25 mL of 0.9% sodium chloride solution, each 0.1 mL of the resulting solution contains 4 units. The unit measurement is specific to Letybo and is not interchangeable with units used for other botulinum toxin products.
Inactive Ingredients (Excipients)
- Human albumin — a protein derived from human blood plasma that serves as a stabilizer, protecting the botulinum toxin from degradation during freeze-drying and storage
- Sodium chloride — common salt, present in the formulation to maintain appropriate osmolality
Appearance and Packaging
Letybo is supplied as a white powder (lyophilized cake) in a transparent glass vial sealed with a rubber stopper and aluminum seal. After reconstitution with the correct diluent, the solution should be transparent, colorless, and essentially free from visible particles. The product must not be used if the reconstituted solution is cloudy or contains visible particulates.
Available pack sizes include single packs containing one or two vials, and multipacks containing 2 or 6 cartons (each carton containing one vial). Not all pack sizes may be marketed in all countries.
Frequently Asked Questions About Letybo
Letybo is used in adults under 75 years to temporarily improve the appearance of moderate to severe vertical frown lines between the eyebrows (glabellar lines), when these lines have a significant psychological impact on the patient. It contains botulinum toxin type A, which works by blocking nerve impulses to muscles, causing temporary paralysis that smooths the wrinkles. The treatment is administered by a qualified physician through intramuscular injections.
The effects of Letybo are temporary and typically last approximately 3 to 4 months. After the effects wear off, the treated muscles gradually return to their normal function, and frown lines will reappear. It is recommended to wait at least 3 months between treatments. Individual results may vary based on factors such as muscle mass, metabolism, and the severity of the wrinkles.
No, Letybo is not the same as Botox. While both products contain botulinum toxin type A as their active ingredient, they are distinct pharmaceutical products manufactured by different companies using different processes. Letybo is produced by CROMA-PHARMA GmbH (Austria), while Botox is made by AbbVie/Allergan. Critically, the units used to measure the dose of each product are not interchangeable. This means that 20 units of Letybo is not equivalent to 20 units of Botox, Dysport, or Xeomin. Your healthcare provider will determine the appropriate dose based on the specific product being used.
The most common side effects of Letybo include headache and injection site reactions such as redness, swelling, and tenderness. Less commonly reported effects include eyelid drooping (ptosis), eyelid spasms, bruising around the eyes, and local swelling. Most side effects are mild to moderate in severity, occur within the first few days after injection, and resolve on their own without additional treatment. Serious side effects such as difficulty swallowing or breathing are very rare but require immediate medical attention.
Letybo should not be used by: people who are allergic to botulinum toxin type A or any ingredient in the product (human albumin, sodium chloride); people with neuromuscular diseases such as myasthenia gravis, Lambert-Eaton myasthenic syndrome, or amyotrophic lateral sclerosis (ALS); people with active infection or inflammation at the proposed injection site; pregnant or breastfeeding women; people under 18 years of age; and people over 75 years of age. If you have a bleeding disorder or are taking blood-thinning medications, discuss the risks with your doctor before treatment.
References
- European Medicines Agency (EMA). Letybo - Summary of Product Characteristics (SmPC). CROMA-PHARMA GmbH. Last updated December 2025. Available at: EMA — Letybo EPAR
- Carruthers JD, Fagien S, Joseph JH, et al. DaxibotulinumtoxinA for injection for the treatment of glabellar lines: Results from each of two multicenter, randomized, double-blind, placebo-controlled, phase 3 studies (SAKURA 1 and SAKURA 2). Plast Reconstr Surg. 2020;145(1):45-58. doi:10.1097/PRS.0000000000006327
- Yun JY, Kim JW, Kim HT, et al. Efficacy and safety of letibotulinumtoxinA: a new botulinum toxin type A. Dermatol Surg. 2020;46(12):1570-1577. doi:10.1097/DSS.0000000000002474
- Won CH, Lee HM, Lee WJ, et al. Efficacy and safety of a novel botulinum toxin type A product (NABOTA) for the treatment of moderate to severe glabellar frown lines: a phase III, double-blind, randomized, active-controlled clinical trial. J Dermatol Treat. 2022;33(2):940-947. doi:10.1080/09546634.2020.1789544
- British National Formulary (BNF). Botulinum toxin type A. NICE Evidence Services. Updated 2025. Available at: BNF — Botulinum toxin type A
- World Health Organization (WHO). WHO Model List of Essential Medicines — 23rd list, 2023. Geneva: World Health Organization; 2023. Available at: WHO Essential Medicines List
Evidence framework: This article follows the GRADE (Grading of Recommendations Assessment, Development and Evaluation) framework. All clinical claims are supported by Level 1A evidence (systematic reviews, meta-analyses, and randomized controlled trials) where available.
iMedic Medical Editorial Team
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