OnabotulinumtoxinA Injection

OnabotulinumtoxinA is a botulinum toxin injection used across a broad range of medical and cosmetic conditions, depending on the specific product.

• Botox — treats overactive bladder (OAB) with urge incontinence, urgency, and frequent urination in adults who haven't responded to anticholinergic medications
• Botox — treats urinary incontinence caused by nerve-related bladder overactivity (e.g., from spinal cord injury or multiple sclerosis) in adults who haven't responded to anticholinergic medications
• Botox — treats neurogenic detrusor overactivity (nerve-caused bladder overactivity) in children aged 5 and older who haven't responded to anticholinergic medications
• Botox — prevents headaches in adults with chronic migraine (15 or more headache days per month, with headaches lasting 4 or more hours); not approved for episodic migraine
• Botox — treats spasticity (muscle stiffness and tightness) in patients aged 2 and older
• Botox — treats cervical dystonia (abnormal head position and neck pain) in adults
• Botox — treats severe primary axillary hyperhidrosis (excessive underarm sweating) in adults when topical treatments haven't worked; safety for sweating in other body areas has not been established
• Botox — treats blepharospasm (uncontrolled eyelid spasms) associated with dystonia in patients aged 12 and older
• Botox — treats strabismus (crossed eyes) in patients aged 12 and older
• BOTOX Cosmetic — contains the same active ingredient as Botox but is approved separately for cosmetic indications

OnabotulinumtoxinA works by blocking the release of acetylcholine — the chemical messenger that nerves use to tell muscles to contract, sweat glands to produce sweat, and the bladder to squeeze. It does this by cleaving (cutting) a protein called SNAP-25 inside nerve endings, which prevents the nerve from releasing its signal. When injected into a muscle, it produces a partial, localized reduction in muscle activity. When injected into the skin, it temporarily stops nearby sweat glands from activating. When injected into the bladder wall, it calms the overactive nerve signals driving urgency and leakage.

The effects are local and reversible — over time, nerve endings can regrow connections to the muscle, which is why repeat injections are needed to maintain the benefit.

OnabotulinumtoxinA is always given as an injection by a trained healthcare professional — never taken by mouth. The route (into a muscle, into the skin, or into the bladder wall) and the number of injection sites depend on the condition being treated. In general, injections are given no more frequently than every 3 months, though the interval may be longer for some conditions.

• For bladder conditions, patients are typically monitored for at least 30 minutes after the procedure and must be able to urinate before leaving
• For chronic migraine, injections are given across multiple sites on the head and neck
• For sweating, injections are placed into the skin of each underarm
• Always follow your prescriber's specific instructions — do not seek re-injection sooner than your doctor advises

Side effects vary by the condition being treated, but the most commonly reported ones include:

• Urinary tract infection, painful urination, or urinary retention (most common with bladder injections)
• Neck pain or headache (most common with migraine or cervical dystonia treatment)
• Pain, bruising, or bleeding at the injection site
• Upper respiratory tract infections or bronchitis (more common with spasticity treatment)
• Sweating in areas other than the underarms (after axillary hyperhidrosis treatment)
• Flu-like symptoms such as nausea, fever, or muscle aches
• Localized muscle weakness near the injection site

Serious reactions — including signs of toxin spread such as trouble swallowing, speaking, or breathing, or severe allergic reactions like hives, swelling, or difficulty breathing — require immediate emergency care.

The biggest risk is spread of the toxin beyond the injection site. OnabotulinumtoxinA can travel from the injection area and cause symptoms such as generalized muscle weakness, drooping eyelids, double vision, trouble swallowing, slurred speech, or breathing difficulty — sometimes hours to weeks later. This has led to deaths in some cases. Children treated for spasticity face the highest risk, but adults can also be affected, especially those with pre-existing swallowing or breathing problems.

• People with neuromuscular diseases (myasthenia gravis, Lambert-Eaton syndrome, ALS) are at much higher risk of severe effects and need close monitoring
• Bladder injections carry a real risk of urinary retention — some patients need to self-catheterize temporarily after treatment
• Bladder injections can increase the risk of urinary tract infections
• Eye injections for blepharospasm can reduce blinking and lead to corneal damage if not monitored
• Strabismus injections carry a rare risk of bleeding behind the eye (retrobulbar hemorrhage)
• Botox units cannot be compared to or converted into units from any other botulinum toxin product — they are not interchangeable

OnabotulinumtoxinA can interact with several types of medications, increasing the risk of excessive muscle weakness or other serious effects:

• Aminoglycoside antibiotics (e.g., gentamicin, tobramycin) — can amplify the toxin's effects; avoid before bladder injections and use with caution at other times
• Curare-like compounds and other neuromuscular blocking agents — can dangerously increase muscle-weakening effects
• Muscle relaxants — can cause excessive muscle weakness when used together
• Anticholinergic drugs — can add to systemic side effects such as dry mouth, blurred vision, and urinary retention
• Other botulinum toxin products — using two different botulinum toxin products close together can cause excessive, unpredictable muscle weakness

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Do not use if you have a known allergy to any botulinum toxin product or to any ingredient in the formulation
• Do not receive injections if there is an active infection at or near the planned injection site
• Do not receive bladder injections if you have an active urinary tract infection, or if you have significant urinary retention and are not routinely self-catheterizing
• Tell your doctor if you have any nerve or muscle disease such as myasthenia gravis, Lambert-Eaton syndrome, or ALS — risk of serious side effects is significantly higher
• Tell your doctor if you have any difficulty swallowing or breathing before treatment
• Tell your doctor if you have a lung or breathing condition — patients with compromised respiratory function need close monitoring, especially when treated for spasticity or bladder issues
• Pregnancy: Based on animal studies, onabotulinumtoxinA may harm a developing baby; discuss the risks with your doctor before treatment
• Breastfeeding: It is unknown whether the medication passes into breast milk; talk with your doctor about weighing risks and benefits
• Children: Botox is approved for spasticity in patients 2 and older, bladder conditions in patients 5 and older, and blepharospasm/strabismus in patients 12 and older; it is not approved for chronic migraine, hyperhidrosis, or cervical dystonia in children
• Older adults: Urinary tract infections and urinary retention were reported more often in patients 65 and older receiving bladder injections; monitor closely

Too much onabotulinumtoxinA can cause widespread muscle weakness throughout the body — symptoms may not appear right away after the injection. If an overdose is suspected, the person should be medically monitored for several weeks for signs of muscle weakness, difficulty swallowing, or breathing trouble. If breathing muscles are affected, mechanical breathing support may be needed. An antitoxin exists and is available through the Centers for Disease Control and Prevention (CDC), but it cannot reverse effects that have already appeared — contact your local or state health department, or the CDC directly at 1-770-488-7100, if poisoning is suspected.

When injected intramuscularly, onabotulinumtoxinA produces a localized, partial reduction in muscle activity by chemically blocking the nerve's ability to trigger muscle contractions. The muscle may gradually shrink (atrophy) with repeated treatment, and over time the nerve can regrow connections, slowly reversing the effect. When injected into the skin, it temporarily shuts down sweat gland activity in that area. When injected into the bladder wall, it reduces the overactive nerve signals that cause urgency and leakage by blocking acetylcholine release along the bladder's nerve pathways.

After intramuscular injection at recommended doses, onabotulinumtoxinA cannot be detected in the bloodstream using current testing methods, meaning it acts locally rather than circulating through the body. Because it works at the injection site and does not reach measurable levels in the blood, standard measures like half-life and metabolism in the liver do not apply in the usual way. The clinical effects wear off over time as nerve endings regrow, which is why repeat treatments are needed.

stored in a refrigerator between 2° to 8°C (36º to 46ºF) for up to 36 months. stored in a refrigerator (2° to 8°C) for up to 24 hours until time of use .