First — it's probably not what you think
If you feel like Botox has stopped working, the most important thing to understand is that true Botox resistance is rare — affecting an estimated 1–3% of long-term users. The majority of patients who feel their Botox isn't working are experiencing something else entirely: underdosing, changed expectations, incorrect placement, or a need to switch brands. These are all fixable without switching to a different class of toxin.
That said — true resistance is real. It exists, it's clinically documented, and when it occurs it does not respond to more Botox, higher doses, or switching brands within the type A category. For those patients, there is a solution most providers don't offer. At Plump Medical Spa in Newport Beach, Dr. Mortazavi is one of the few practitioners in Orange County who uses Myobloc — a type B botulinum toxin — specifically for resistance cases.
The real reasons Botox stops working
01
Underdosing — the most common cause
The most frequent reason patients feel Botox "isn't working" is simply inadequate dosing. Providers often underdose to reduce cost or be conservative with first-time patients. As patients' muscles become more accustomed to treatment, the same dose produces less visible effect. The answer is not a different product — it is the correct dose for your muscle mass and treatment area.
Most common
02
Wrong placement or technique
Botox placed in the wrong muscle group, at the wrong depth, or in the wrong location fails to produce the expected result — and is misattributed to product failure. For example, treating the glabella when the forehead is the primary concern, or treating the wrong level of a muscle produces partial or absent results that have nothing to do with resistance.
Very common
03
Switching brands without adequate time
Each type A toxin (Botox, Dysport, Xeomin) has different unit equivalencies and diffusion properties. Switching from one to another without adjusting dosing often produces a result that appears weaker — not because of resistance, but because the dose translation was incorrect.
Common
04
Fast metabolism
Some patients — particularly those with higher physical activity levels — metabolize neurotoxin faster than average. Results wear off in 6–8 weeks rather than 3–4 months. This is not resistance — it is metabolic clearance. More frequent treatment intervals or higher initial doses are the solution.
Confirm with provider
05
True antibody-mediated resistance
The immune system develops neutralizing antibodies against the botulinum toxin protein, rendering it ineffective before it can act on the neuromuscular junction. More common in patients with long treatment histories, frequent top-ups, or high cumulative doses. Confirmed when all type A products fail at appropriate doses with correct technique. Myobloc (type B) typically still works in these patients.
Less common — but real
How to tell the difference
The diagnostic test for true resistance is systematic: try Xeomin (the purest type A toxin with the lowest protein load) at a verified adequate dose, administered by a skilled physician with correct technique. If Xeomin at appropriate dose with verified placement produces no result within 10–14 days, true antibody-mediated resistance becomes the likely explanation and Myobloc becomes the next step.
What is Myobloc — and why it works when nothing else does
Botox, Dysport, Xeomin, and Daxxify are all type A botulinum toxins. They block the neuromuscular junction through the same mechanism and are targeted by the same neutralizing antibodies in resistant patients. Switching between them in a true resistance case produces no benefit — they are neutralized by the same immune response.
Myobloc (rimabotulinumtoxinB) is a type B botulinum toxin. It blocks the neuromuscular junction through a different molecular mechanism. Patients who have developed antibodies against type A toxins typically have no cross-reactive immunity to type B — which is why Myobloc works in patients who no longer respond to any type A product.
Type A — standard
Botox / Dysport / Xeomin
Toxin typeBotulinum A
MechanismSNAP-25 protein cleavage
Onset3–7 days
Duration3–4 months
Works for resistant patientsNo — same antibody target
Availability in OCUniversal
Type B — for resistance
Myobloc (rimabotulinumtoxinB)
Toxin typeBotulinum B
MechanismVAMP/synaptobrevin cleavage
Onset24–48 hours
Duration6–10 weeks
Works for resistant patientsYes — different mechanism
Availability in OCRare — Plump is one of few
The tradeoffs of Myobloc
Myobloc works — but it is not a perfect substitute for Botox. There are real tradeoffs that patients considering it should understand before their appointment.
Duration is shorter. Myobloc typically lasts 6–10 weeks compared to Botox's 3–4 months. Patients who use Myobloc regularly plan for 5–6 appointments per year rather than 3–4. For patients who have had no effective treatment for months or years, even 6–8 weeks of relief is meaningful.
Dry mouth is more common. Type B toxin has a higher affinity for autonomic nerve fibers compared to type A. Temporary dry mouth is a known side effect of Myobloc, particularly at higher doses. It typically resolves as the treatment wears off. Staying well hydrated during the treatment period helps.
Cost is higher per session. Myobloc is more expensive to produce and stock than type A toxins, which is one of the reasons most practices do not carry it. At Plump, Myobloc starts at $500 per session.
Dr. Mortazavi uses Myobloc himself. This is not a theoretical recommendation — it is a treatment he has personal clinical experience with. At Plump Medical Spa, Myobloc is not a fallback option offered grudgingly. It is a core specialty of the practice, and patients travel from across Orange County and Southern California specifically because Plump is one of the few practices that offers it well.
Frequently asked questions
Why has Botox stopped working for me?
The most common reasons are underdosing, incorrect placement, or fast metabolism — not true resistance. True antibody-mediated resistance is rare (1–3% of long-term users) and is confirmed only after adequate doses with correct technique fail to produce any result across multiple type A products.
Does switching from Botox to Dysport or Xeomin help with resistance?
Switching between type A products (Botox, Dysport, Xeomin, Daxxify) does not help in cases of true antibody-mediated resistance — they are all targeted by the same neutralizing antibodies. Switching brands is appropriate if dosing or technique adjustments haven't worked, as a diagnostic step. If all type A products fail at verified doses, Myobloc (type B) is the next step.
What is Myobloc?
Myobloc (rimabotulinumtoxinB) is a type B botulinum toxin that works through a different mechanism than Botox, Dysport, and Xeomin. Patients with antibodies against type A typically do not have cross-reactive immunity to type B — which is why Myobloc works in true resistance cases. It has a faster onset (24–48 hours) and shorter duration (6–10 weeks) compared to type A products.
How much does Myobloc cost at Plump Medical Spa?
Myobloc at Plump Medical Spa in Newport Beach starts at $500 per session. Exact pricing depends on the treatment areas and number of units required. Dr. Mortazavi determines appropriate dosing at consultation.
Can I come to Plump even if my filler was done elsewhere?
Yes — and this applies to Myobloc consultations as well. Patients who have been told their Botox is no longer working by other providers are welcome. Dr. Mortazavi evaluates the history, assesses candidacy, and determines whether true resistance or another cause explains the reduced response before recommending Myobloc.