Vascular Occlusion Warning Signs and the First Hour Response

This article is intended for qualified aesthetic practitioners. It is educational and does not replace accredited complications training, your own clinical judgement or the full published guidelines referenced below.

Vascular occlusion is the complication every injector plans for and hopes never to see. It happens when filler enters or compresses a blood vessel, cutting off supply to the tissue that vessel feeds. Caught in the first minutes, most cases resolve. Missed, or mistaken for a bruise, it can progress to skin breakdown, scarring and, rarely, permanent loss of vision.

Below: the warning signs in the order they appear, arterial versus venous patterns, how to separate occlusion from bruising, and a structured first-hour response.

Why vascular occlusion happens

There are two broad mechanisms. In an arterial event, product is injected directly into an artery or embolises within it, travelling downstream until it lodges and blocks flow. In a venous event, filler or the swelling that follows it presses on veins from outside, slowing drainage. The ACE Group guideline on managing vascular occlusion notes that venous compression is seen more often with hyaluronic acid fillers, and that arterial events typically present immediately while venous ones tend to show up later.

Events are under-reported, but the ACE Group paper cites an estimated incidence of around 1 in 100,000 for dermal fillers overall, alongside a survey of 52 injectors in which 62% said they had experienced at least one intravascular event. The per-syringe risk is low, but many injectors will manage at least one over a career.

The higher-risk areas

Any area can be affected, but some carry more risk because of vessel density, end-artery anatomy or connections to the ophthalmic circulation. The glabella is the classic example: the ACE Group paper states that around half of reported vascular occlusion cases arise from glabellar injections. For visual complications specifically, a 2024 review in Aesthetic Surgery Journal identified 365 new cases of partial or complete vision loss published between 2018 and 2023, with the nose (40.6%), forehead (27.7%) and glabella (19.0%) the most common sites. Hyaluronic acid was the product in 79.6% of those cases.

Lips need the same vigilance, given the volume of lip work and the superficial course of the labial arteries. Nose work deserves particular respect: an earlier literature review in the Journal of Cosmetic Dermatology found nasal augmentation carried the greatest risk of filler-induced visual compromise in its dataset. If you offer non-surgical rhinoplasty fillers, your training, consent process and emergency preparation should reflect that.

Vascular occlusion symptoms, in the order they appear

The ACE Group guideline (adapted from De Lorenzi) sets out a useful timeline. Knowing what to expect at each stage helps you avoid both false reassurance and panic.

• Immediately, or within seconds: pain. Filler treatment is not normally associated with severe pain, so sudden or escalating pain warrants an urgent review. Pain felt away from the injection site is also a warning sign. Bear in mind that lidocaine in the product or a nerve block can mask it.
• Immediately: blanching. The area looks pale, white or dusky and stays that way after the needle or cannula is withdrawn. Blanching can be transient, and adrenaline in local anaesthetic can mimic or hide it.
• Minutes to tens of minutes: livedo. A reticulated, mottled, lace-like pattern develops as perfusion becomes patchy.
• Minutes: delayed capillary refill. The guideline treats a capillary refill time of more than three seconds as suggestive of vascular compromise.
• Tens of minutes to hours: blue-grey or dusky purple colour as deoxygenated blood builds up in the tissue. Coolness of the skin is not usually apparent straight after injection.
• Days: skin breakdown, which may be followed by repair over days to weeks.

How to check capillary refill properly

Apply moderate pressure to the area for five seconds, release, and time how long the colour takes to return. Always compare with the equivalent untreated area on the other side. The ACE paper cites normal values of around two seconds for men under 65, three seconds for women under 65 and four seconds in older patients, which is why a side-to-side comparison matters more than a single number. A brisk refill sitting on top of bluish discolouration can point towards venous insufficiency rather than arterial blockage.

Arterial or venous: reading the pattern

• Arterial occlusion usually announces itself during or immediately after injection: acute pain, blanching, then livedo and slow refill.
• Venous occlusion tends to present later, sometimes hours after the patient has left, with a duller ache or no pain at all and a darker, congested discolouration.

Because venous events can surface after discharge, aftercare information should tell patients exactly which changes to report and how to reach you out of hours. The ACE Group is explicit that a suspected occlusion must be reviewed in person, not judged from photographs or messages.

Vascular occlusion vs bruising

A bruise needs reassurance; an occlusion needs treatment. The key test is blanching under pressure. A bruise is blood that has leaked into the tissue, so it does not blanch when pressed. The duskiness of vascular compromise comes from deoxygenated blood sitting in the vessels, and it behaves differently on a refill test.

Other pointers that favour occlusion over bruising:

• The discolouration follows a vascular territory or a net-like livedo pattern, rather than sitting as a discrete patch around an entry point.
• Pain is out of proportion to the procedure, or is increasing rather than settling.
• Capillary refill on the affected side is slower than on the untreated side.
• The colour is spreading or darkening over time.

If you are unsure, treat it as an occlusion until proven otherwise.

The first-hour response

The ACE Group describes vascular occlusion as a time-critical event. A sensible sequence, drawn from its guideline, looks like this:

1. Stop injecting immediately. If possible, aspirate as you withdraw the needle or cannula.
2. Tell the patient what is happening, calmly and honestly, and document the time.
3. Apply conservative measures: firm massage, which may be needed for several minutes, warmth to encourage vasodilation, and tapping over the area.
4. Reassess capillary refill and colour. If refill is sluggish but not beyond three seconds, conservative measures may be enough. If there is no improvement, or refill exceeds three seconds, the guideline moves to hyaluronidase.
5. Follow the published hyaluronidase protocol for HA fillers. The ACE Group recommends a high-dose, pulsed approach: treating the whole area of compromised tissue, not just the injection point, and repeating hourly until refill, colour and pain show clinical resolution. It states that skin testing is not required in this emergency because the risk of tissue loss generally outweighs the risk of an allergic reaction. Dosing and administration should come from the guideline itself and your prescriber, not from a blog post.
6. Consider adjuncts the guideline describes, including aspirin where there are no contraindications. It no longer recommends topical nitroglycerin, and it advises against prophylactic antibiotics where the skin is intact.
7. Escalate early if you are out of your depth. Contact a more experienced colleague or a complications service.

Hyaluronidase is a prescription-only medicine, so non-prescribing practitioners must have a clear, pre-agreed arrangement with a prescriber who can respond quickly. Sorting that out on the day of a complication is too late.

Any visual symptom is a 999 emergency

Sudden blurred vision, visual loss, eye pain, a drooping eyelid, restricted eye movement or neurological signs after treatment near the nose, glabella or forehead need emergency hospital care, not a wait-and-see approach in clinic. The 2024 Aesthetic Surgery Journal review found ptosis in 56.2% and ophthalmoplegia in 44.1% of visual-loss cases, and stroke-like features in 19.2%. Outcomes were poor: of cases reporting them, 68.2% saw no recovery of vision.

Follow-up after a vascular occlusion

The ACE Group advises that every patient with a vascular occlusion is followed up until the problem has fully resolved, which may mean daily review at first. Photograph each visit and keep a clear timeline of what was done and when. If more filler is needed once everything has settled, the paper suggests an interval of 7 to 14 days before retreating.

Reducing your risk before you inject

No technique removes the risk entirely, but several habits lower it:

• Know the anatomy of every area you treat, including variant vessel courses.
• Consider a cannula in higher-risk planes. The ACE paper notes that cannulas of 25G or larger are less likely to penetrate vessels than sharp needles. Our cannulas range covers common gauges and lengths, and we have written separately on lip filler techniques from tenting to cannula.
• Do not rely on aspiration alone. The ACE paper cites studies putting the reliability of aspiration at roughly 33% to 63%, so a negative aspirate is not proof you are outside a vessel.
• Inject slowly, with low pressure and small aliquots, and keep the needle or cannula moving where appropriate.
• Choose products suited to the area. Using a filler designed for the depth and tissue you are treating, from our lip filler collection for example, helps you avoid overcorrection and excess volume that can add to compression.
• Keep an emergency kit stocked and in date, with your protocol and prescriber contact details to hand.

Frequently asked questions

How quickly does vascular occlusion happen?

Arterial events usually show signs during injection or immediately after, with pain and blanching within seconds and livedo developing over minutes. Venous occlusion can take longer and may appear hours after treatment, which is why patients need clear instructions on what to report.

What does vascular occlusion look like in lip filler?

Early on, a pale or white area along the lip that does not refill properly, often with disproportionate pain. Over the following minutes this can become a mottled, lace-like pattern, then a dusky blue-grey or purple colour. Compare refill with the unaffected side of the lip.

How can you tell bruising from a vascular occlusion?

Press on it. A bruise is leaked blood and does not blanch under pressure. Vascular compromise is associated with slow capillary refill, a livedo pattern, escalating pain and colour that spreads or darkens over time. If in doubt, manage it as an occlusion.

Final thoughts

Vascular occlusion is rare for any single treatment but a real possibility over a long injecting career. The practitioners who manage it well are not the ones who never encounter it; they are the ones who recognise it in the first minutes, already have a prescriber and a protocol in place, and follow up until the tissue has fully recovered. Read the full ACE Group guideline and rehearse your response with your team. For a related complication, see our piece on preventing and correcting the Tyndall effect.