Botox® is a popular FDA-approved therapeutic and cosmetic procedure in part because it is relatively easy for trained practitioners to administer in controlled clinical settings.
Since the early 2000s, the FDA and other health authorities in the United States have approved Botox to treat more than a dozen cosmetic and musculoskeletal conditions, from frown lines to migraines. Medical professionals have safely administered Botox Cosmetic and Botox Therapeutic, the two products marketed under the Botox trade name, to millions of individual patients during this period.
While Botox administration is not of the same degree of difficulty as inpatient surgery and does not require years of training to provide, it is nevertheless a significant medical procedure that carries appreciable risks. Clinicians who wish to add Botox treatment in their practice must understand how to inject Botox safely: best practices for diluting the medication, evaluating treatment candidates, selecting injection sites, ensuring proper dosing, and following up with patients after treatment.
While practitioners will require a Botox training course, this article is a good start as it covers all the above topics and more. Let’s first review what you can expect from the remainder of the material here, then jump into an overview of injection procedures and technical specifications for the medication.
What to Expect From This Guide on How to Inject Botox
- How Botox is injected
- Technical specifications for the medication and general injection procedures
- How Botox works on human nerves and muscles
- How to evaluate treatment candidates and spot contraindications before injection
- Monitoring Botox injection sites and patients for possible side effects and complications
How Is Botox Injected?
Botox treatment is an outpatient procedure that, including post-procedure observation, can usually be completed within an hour’s time.
Botox is generally administered by intradermal injection (into the layer of skin below the dermis) or subcutaneous injection (into the fat layer below the skin). The angle of entry is important: too shallow and the medication may not diffuse through the target muscle; too deep and the risk of systemic complications may increase. Care must be taken to avoid major blood vessels and nerves.
Botox Dilution and Injection Protocols
Injection protocols vary by procedure. For example, Botox treatment for bruxism typically involves a total of eight injections of 4 to 5 units in three facial muscles:
- Masseter muscle: 2 injections, 4 to 5 units each
- Temporalis muscle: 4 injections, 4 to 5 units each
- Lateral/medial pterygoid muscle: 2 injections, 4 units each
Finer cosmetic treatments typically necessitate fewer injections. The typical course for treatment of depressed nasal tip is generally just 2 injections at 3 units each (6 units total).
Refer to these injection guidelines for common Botox-treated conditions, keeping in mind that while facial anatomy is consistent, every patient is different and actual unit counts will vary within these ranges:
- Forehead lines: Anywhere from 5 to 25 units is adequate, depending on the extent of the treatment area. Inject well above the brow line to reduce the risk of ptosis (eyelid droop), a common Botox side effect.
- Mentalis muscle (for “dented chin”): Up to 20 units, depending on the extent of the dent.
- Transverse nasal lines (“bunny lines”): Anywhere from 5 to 25 units is indicated, with more for deeper or more extensive lines.
- Perioral lines (“smokers’ lines”): No more than 5 or 6 units is indicated, with less for finer lines.
- Crow’s feet: Anywhere from 5 to 15 units is indicated, depending on depth and extent.
Botox dilution is vitally important. Clinicians must refer to the correct dilution guidelines (Botox Cosmetic or Botox Therapeutic) to ensure safe, effective treatment. For example, the Botox Cosmetic dilution guidelines require 2.50 mL of diluent (sterile sodium chloride solution) per 100-unit vial to produce a dose containing 4 units per 0.1 mL — the approved dose at each of the five injection sites in a typical glabellar lines treatment.
Dilution guidelines may vary by procedure. Micro Botox, a shallow-angle procedure that smooths fine lines in the face and neck, requires dozens or hundreds of injections of highly dilute “microdroplets”: 10 to 20 injections per 0.05 mL (2-unit) droplet.
How Botox Works on Human Nerves and Muscles
Botox works by blocking the release of acetylcholine, a neurotransmitter that instructs muscles to contract. The result is a temporary paralysis of the affected muscles. Following Botox injection, treated muscles are either entirely unable to contract on their own or have greatly reduced motility.
In certain contexts, Botox may block or inhibit the release of other key neurotransmitters. For example, Botox is effective in treating pain associated with chronic migraine headaches and in quelling the headaches themselves because it blocks the release of glutamate, an excitatory neurotransmitter that transmits pain signals. Botox may act on glutamate signals over longer time spans than on acetylcholine signals, making it an effective treatment for migraine-related pain.
Evaluating Treatment Candidates and Identifying Contraindications
Patients are generally not good candidates for Botox treatment (and other cosmetic injectables) if they present with any of the following medical issues:
- Certain conditions that require ongoing medical monitoring, such as myasthenia gravis or Lambert-Eaton syndrome
- Certain serious, chronic underlying health conditions, such as congestive heart failure, diabetes (Type 1 or 2), or rheumatoid arthritis
- Known sensitivity to any component of treatments derived from botulinum toxin A, including the toxin and inactive ingredients like albumin, sucrose, or lactose
- Appreciable facial asymmetry, ptosis, or other anatomical defects
- Known history of facial palsy
- Current or recent skin infection in the area of treatment
- Current pregnancy, expected/planned pregnancy, or breastfeeding
Patients taking certain medications are not suitable for Botox treatment either, including (but not limited to):
- Anticoagulants, such as warfarin
- Aminoglycoside antibiotics
- Drugs that may increase the potency of Botox, including muscle relaxers
- Drugs that may interfere with or reduce the potency of Botox
Age is also an important consideration. There is no agreed-upon age threshold for the general contraindication of Botox, but older patients are more likely to present with medical contraindications and/or experience side effects and complications from treatment. Providers should balance older patients’ desired outcomes against these potential risks.
After the Injection: Monitoring for Possible Side Effects and Following Up Treatment
Botox side effects and complications are rare but can occur following any treatment, regardless of the dosing or underlying condition being treated. Providers must understand these risks prior to treatment, counsel treatment candidates accordingly, and be prepared to follow up with and monitor patients as necessary.
The most common side effects for Botox injected in the face and forehead affect facial expressions and include smile abnormalities (crooked or lopsided grin) and eyelid drooping. These depend on the injection location. Other localized or generalized side effects can include:
- Swelling or pain near the injection site
- Bruising or redness near the injection site
- Headache or a feeling of pressure in the head
- Flulike symptoms
The active ingredient in Botox is capable in rare cases of spreading beyond the local injection site and causing systemic complications that may be serious. Such complications may include but aren’t limited to:
- Muscle weakness throughout the body or in specific muscle groups
- Loss of bladder control (urinary incontinence)
- Difficulty speaking or swallowing
- Vision problems
Short-term complications can occur within minutes of treatment, necessitating onsite patient monitoring immediately following injection. Providers should advise patients against physical activity for 24 hours after treatment and instruct patients to contact them with concerns.
Moving forward, Botox injection intervals vary by patient and the condition being treated. Botox’s effects typically last at least three to four months and may last longer, depending on dosing and injection site. The recurrence of symptoms and the patient’s tolerance for treatment will influence injection frequency as well. Providers should counsel patients not to expect permanent changes following Botox treatment, as botulinum toxin A does not address the root causes of the conditions it is approved to treat and its efficacy wanes as the toxin leaves the system.