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January 27, 2026
Dr Tim Pearce
One of the most common questions asked by aesthetic clinicians in complications forums is what to do if your patient is allergic to hyaluronidase but you need to treat a vascular occlusion (VO).
In this blog Dr Tim Pearce discusses the issue of hyaluronidase allergy and the impact this may have on delivering an emergency reversal when managing a vascular occlusion incident, weighing up the risks of treatment versus the risks of anaphylaxis.
Do you feel anxious about causing complications? Many clinicians feel so overwhelmed with the thought of causing a vascular occlusion that it stops them growing their aesthetics business. Dr Tim is currently hosting a webinar series to help you overcome your fear of complications so that you can uplevel your knowledge, and increase your CPD-certified learning to build a successful aesthetics business. Sign up here >>
How do you know if your patient is allergic to hyaluronidase?
Diagnosing an allergy to hyaluronidase is very different to just knowing it as a fact, says Dr Tim. If you have a patient who received hyaluronidase in the past (with you or elsewhere) and they had a significant reaction, then you can make the diagnosis of allergy with certainty.
At the other end of the spectrum, we turn to risk factors. A common one is an allergy to bee stings and the assumed corollary that they must be allergic to hyaluronidase, with many practitioners using this as a complete contraindication, which Dr Tim disputes. He notes that there are approximately fifty-two different compounds within bee stings and only one of them is hyaluronidase, thus you cannot say with 100% certainly that the patient is allergic to hyaluronidase due to a history of bee sting allergy. Therefore, you must decide how to determine if they are truly allergic. You can perform an intradermal test with hyaluronidase, which will provide some information, but like any screening test, it is not black and white, there are false positives and false negatives.
Results can range from minor, mild erythema which might just be part of the normal process of injecting into the skin, to a large, red, raised weal, and everything in between; this can be confusing. As aesthetic clinicians, we must try and decide on the use of hyaluronidase, or not, based on these results. A difficult decision when you are faced with a vascular occlusion.
Top Tip from Dr Tim
“When performing your hyaluronidase intradermal screening test, add in a control for a little more certainty to your results. Do this by injecting a small amount of saline next to the area and compare it with your test injection of hyaluronidase solution. This enables you to see how much reaction is from the action of injection, rather than specifically the hyaluronidase.”
Approximately one in two thousand people will have some kind or level of allergy to hyaluronidase, this does not mean straight to anaphylaxis, and this also means that it is not common. Sadly, this information relies on data reporting, and Dr Tim suspects that a lot of allergic reactions go unreported, thus data is poor. He encourages all aesthetic clinicians to use the MHRA’s Yellow Card reporting system if they experience hyaluronidase reactions as it adds to the wealth of knowledge for us all.
What should you do in the event of a vascular occlusion with an allergic patient?
Check out another of Dr Tim’s blogs for additional advice on managing a vascular occlusion using an emergency protocol and how many vials of hyaluronidase you might require.
Broadly speaking there is a consensus that if it is a medical emergency, like a vascular occlusion, you can go ahead and reverse it with hyaluronidase and you do not need to perform an intradermal test. These tests are not 100% indicative, one way or the other, therefore it is better to start the process of reversing the compromised blood flow to the area of tissue. Of course, there is the chance of a reaction after your first injection, which is likely to cause you to stop treatment, even small doses can result is dramatic reactions like swelling.
Therefore, Dr Tim believes that it is reasonable to look for some risk factors first, before you dive in – ask your patient if they are allergic to bees, for example. Then consider your clinic set-up and the risks to you and your patient, especially if the answer to that question is yes. If you are in a remote location, miles from a hospital, and you only have a single EpiPen® in clinic, your decision process will be different to a clinic fully stocked with adrenaline and oxygen in an emergency bag.
Depending on your circumstances, you could decide that an intradermal test might be helpful before you consider reversing the VO, especially if it yields a significant reaction which could indicate a potential for anaphylaxis or severe allergic reaction (e.g., swelling of the face and neck) were you to deliver multiple vials of hyaluronidase. However, Dr Tim understands that there is a lack of data to dictate actions from the results of an intradermal test, with certainty – how big does the weal have to get to determine likelihood of a significant allergic response?
Experience is often the key, and Dr Tim highlights that he has been performing intradermal tests for elective reversals for many years which means that he has seen many results. To diagnose an allergy, he looks for a positive reaction that is undeniably clear – a significantly large, swollen, red, itchy lump would deter him from proceeding with hyaluronidase due to the risk of triggering a full-blown anaphylactic reaction.
Planning for these real-world scenarios and being well prepared is critical. Healthcare professionals are always balancing the risks – the benefits versus potential harm. As the risk goes up, we must justify it with the benefits that it is likely to yield. However, it gets more difficult to justify the action, the more allergic someone is, or the more information you have pointing to the fact that they might be allergic.
So, what you do when there is a clear allergic reaction, and you have a vascular occlusion?
Dr Tim warns that you should think this through, before you get into that situation, so you know and understand your plan because chances are when you are in the thick of it your brain will not be functioning normally, you will be anxious, stressed, and unable to think clearly, so you must pre-plan. Think about the worse case scenario.
What are the worst possible outcomes of treating a patient with a known allergy to hyaluronidase?
In medical aesthetics, we tend to think of vascular occlusions as one of the worst things that can happen in clinic. Therefore, we put it at the top, it is a 10 out of 10 level medical emergency in our specialty.
The truth, however, explains Dr Tim, is that if you were to send your patient to Accident & Emergency with a vascular occlusion in their lip, for example, the department will not react like it is a 10 out of 10 level medical emergency. That patient will sit in the minor injuries triage section whilst they wait for patients with cardiac arrests to be attended first. Most vascular occlusions are serious and important for the patient, but it is a minor injury.
Similarly, it is an emergency to treat them before you risk necrosis in the area, but it cannot be put it in the same bracket of emergency as anaphylactic shock. Even if you did nothing to treat the VO and it became necrotic, the patient is not going to die. Yes, they will be upset and likely have long-term skin irregularities or scarring to the area after it has recovered.
Therefore, this is the crux of the situation – you are weighing up the potential of a small scar, in most cases, if you leave it to naturally recover (and use other aids to mitigate the VO), against the potential of triggering an anaphylactic reaction in a patient you already know to be allergic to hyaluronidase.
For that reason, concludes Dr Tim, he would not recommend carrying out a full reversal procedure with hyaluronidase when you have evidence that the patient may be allergic, because you cannot justify the risk of them having an anaphylactic reaction and dying. You would find it very hard to defend your position in court or in a fitness to practice hearing and could risk your medical license to practice.
For more information on using hyaluronidase to manage vascular occlusions from dermal filler injections, download Dr Tim Pearce’s Emergency Reversal Protocol.
You can find Dr Tim Pearce on Instagram if you have any further questions or comments about injecting the zygoma and cheek area with dermal fillers.
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Aesthetics Mastery Show
What If Patient’s Allergic To Hyaluronidase?
In this episode, Dr Tim debates whether it’s best to proceed with the hyaluronidase reversal and risk anaphylaxis, or to stand by and wait for the inevitable skin necrosis. Watch the full Aesthetics Mastery Show here.
The video has been watched over 16,000 times and has great comments from practitioners and injectors, including:
Very interesting. I had a patient clearly allergic to porcine derived hyaluronidase but not bovine. She also was not allergic to bees. Thanks for another very in depth and educational show.
Panda1122 A
This is the most informative video regarding the allergic to hyalase. You are wonderful. You have answered all the questions those always played in my mind. Thank you very much for it
Tahira Kashif
A number of patients also shared their experiences.
Read more and join in the debate on our YouTube channel.
Filler Complications eLearning Courses
If you want to increase your confidence by learning how to handle complications, Dr Tim Pearce offers two comprehensive courses that are highly rated by our delegates:
Both give CPD and certificates on completion.
In addition, browse our FREE downloadable resources on complications.
Dr Tim Pearce eLearning
Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.
Our exclusive video-led courses are designed to build confidence, knowledge and technique at every stage, working from foundation level to advanced treatments and management of complications.
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