Angioedema and COVID-19: Causes, Symptoms & Treatment

COVID-19 can trigger angioedema, a rapid and sometimes dangerous swelling of deeper skin and mucosal tissues, through a mechanism that has little to do with a typical allergic reaction. The virus disrupts the body’s bradykinin system, the same chemical pathway involved in blood-pressure regulation and inflammation, leading to fluid leaking from blood vessels into surrounding tissue. This connection matters because bradykinin-driven swelling does not respond to the standard allergy medications most emergency rooms reach for first, and recognizing the difference can change outcomes.

How SARS-CoV-2 Sets Off Swelling

The virus that causes COVID-19 enters cells by latching onto a protein called ACE2 on cell surfaces. ACE2 normally helps break down bradykinin, a small molecule that dilates blood vessels and increases their permeability. When SARS-CoV-2 binds to ACE2, it effectively pulls ACE2 out of commission, and bradykinin and its breakdown products accumulate instead of being cleared.¹ The excess bradykinin forces plasma out of blood vessels and into surrounding tissues, producing the characteristic non-itchy, deep swelling of angioedema.

Researchers have also proposed that SARS-CoV-2 infection directly reduces levels of C1 esterase inhibitor, a protein that normally keeps the contact activation system (including bradykinin production) in check.² Losing both the ACE2 breakdown pathway and the C1 inhibitor brake at the same time creates a kind of double hit: bradykinin floods the system with no adequate mechanism to rein it in. This helps explain why angioedema can appear in COVID-19 patients who have no history of allergies or swelling.

What COVID-Related Angioedema Looks and Feels Like

Angioedema tied to COVID-19 tends to affect the face, lips, mouth, and tongue, and it develops without the hives or itchiness that typically accompany allergic swelling.³ In hospitalized patients, particularly those on ventilators, the onset of facial swelling and tongue protrusion has been observed roughly ten to fourteen days after intubation.³ That timeline fits a bradykinin-driven process rather than an immediate allergic event, which would start within minutes of exposure to a trigger.

In less severe COVID-19 cases, angioedema can still appear. One report described a 37-year-old man with no prior medical history apart from a recent COVID-19 infection who developed swelling of the lips and upper arms along with hives and mild abdominal pain.⁴ Abdominal pain is worth noting: angioedema can affect the intestinal wall, causing cramping and nausea that may be misread as a gastrointestinal illness rather than a swelling episode.

A case series of African American COVID-19 patients who developed angioedema found that none had the hallmarks of a histamine-driven allergic reaction, meaning no skin rash and no elevation in certain white blood cells associated with allergies.⁵ The absence of those features is a clinical red flag: it points toward bradykinin as the culprit and signals that antihistamines and epinephrine are unlikely to help.

Why ACE Inhibitors Add Risk

ACE inhibitors are among the most commonly prescribed blood-pressure medications worldwide. They work by blocking angiotensin-converting enzyme, which has a side job of breaking down bradykinin. Even without COVID-19, ACE inhibitors carry a small but well-known risk of angioedema because they let bradykinin build up. When COVID-19 enters the picture, both the drug and the virus are independently suppressing bradykinin clearance, and the combined effect can push levels past the tipping point.

One case involved a 57-year-old man who had been taking the ACE inhibitor benazepril for four months without problems. He showed up at the emergency room with tongue swelling, shortness of breath, and difficulty speaking, and only later tested positive for COVID-19.⁶ The implication is that the virus tipped a precarious balance: benazepril alone had not caused angioedema, but benazepril plus SARS-CoV-2 did.

African Americans may face elevated risk in this scenario. ACE inhibitor-induced angioedema is already more common in Black patients for reasons that are not fully understood, and the additional bradykinin burden from a SARS-CoV-2 infection may amplify that vulnerability.⁷ Early in the pandemic, there was debate about whether patients should stop ACE inhibitors to reduce COVID-19 complications. Medical guidelines ultimately advised continuing the medications because the cardiovascular benefits outweigh the angioedema risk for most people, but the interaction remains something clinicians should watch for.⁶

Bradykinin-Mediated Versus Histamine-Mediated Swelling

This distinction is arguably the most critical piece of practical knowledge for anyone dealing with angioedema in the context of COVID-19. Histamine-mediated angioedema is the kind most people are familiar with: it accompanies allergic reactions, shows up with hives and itching, and responds to antihistamines, steroids, and epinephrine. Bradykinin-mediated angioedema is a different animal. It tends to come on more slowly, favors the face and oropharyngeal area, and carries a higher risk of progressing to airway obstruction. Critically, it does not respond to steroids, antihistamines, or epinephrine.⁸

This matters because emergency departments reflexively treat acute swelling episodes with epinephrine and steroids. When COVID-19 is driving angioedema through bradykinin, those standard treatments may simply fail. Clinicians in published case reports have noted that steroids did not alleviate symptoms in COVID-19 angioedema patients, consistent with a bradykinin-driven mechanism.³ For the patient, the practical takeaway is straightforward: if you develop facial or throat swelling during or shortly after a COVID-19 infection and standard allergy treatments are not working, make sure the treating team considers bradykinin-mediated angioedema. It requires different drugs.

Treatment Approaches

When angioedema occurs alongside more common COVID-19 skin symptoms like hives, antihistamines combined with low-dose systemic steroids have shown benefit. The antihistamines help with the itching and surface-level swelling, while steroids dampen the broader inflammatory storm that activates the cells releasing histamine in the first place.⁹ This combination works when histamine is the primary driver.

For bradykinin-mediated episodes, the treatment toolkit is different and more specialized. Two drugs already approved for hereditary angioedema have attracted attention: icatibant, which blocks the bradykinin B2 receptor, and plasma-derived C1 inhibitor concentrate (pdC1INH), which replaces the regulatory protein that SARS-CoV-2 depletes. A randomized trial tested both agents against standard care in severe COVID-19 patients, and both showed improvements in lung imaging scores.¹⁰ Follow-up cardiac imaging found that pdC1INH significantly reduced markers of heart muscle swelling and cell enlargement, suggesting it may offer protection beyond the lungs. Icatibant showed less favorable cardiac effects by comparison.¹¹

These targeted therapies remain expensive and not universally available, and the evidence base is still built on relatively small studies. For most patients experiencing mild to moderate angioedema during a COVID-19 infection, supportive care and close monitoring of the airway are the main approach. The targeted bradykinin-blocking drugs are most relevant in severe hospitalized cases or when swelling threatens the airway and standard treatments are failing.

The Link to Severe Lung Disease

The bradykinin storm does not stop at visible swelling. The same mechanism that causes facial and throat angioedema can affect the lungs from the inside. Excess bradykinin increases vascular permeability in the lung tissue, and one analysis found that the resulting fluid shifts combine with increased production of hyaluronic acid in the lung’s air spaces to form a gel-like substance that impairs oxygen exchange.¹² This “internal angioedema” of the lungs may contribute to the severe respiratory distress seen in some COVID-19 patients, and it helps explain why the disease sometimes progresses rapidly to respiratory failure even when chest imaging does not initially look alarming.

From a treatment standpoint, if bradykinin is driving part of the lung pathology, then bradykinin-targeted therapies could in theory address respiratory deterioration alongside visible angioedema. That is the rationale behind the clinical trials using icatibant and C1 inhibitor concentrate in severe COVID-19, as described above. The evidence so far is suggestive but not yet strong enough to make these treatments standard of care for COVID-19 lung disease broadly.

Angioedema After COVID-19 Vaccination

Angioedema has also been reported as an uncommon side effect of COVID-19 vaccines, though the mechanism differs from what happens during actual infection. One case described a young woman who developed severe swelling with elevated eosinophils, a pattern called nonepisodic angioedema with eosinophilia, about a week after her second dose of the Pfizer-BioNTech mRNA vaccine. Her symptoms gradually resolved over roughly ten weeks with supportive care and without steroids.¹³ Notably, this was an eosinophilia-associated pattern rather than a bradykinin-mediated one, meaning it represents a different immune pathway entirely from the infection-related angioedema discussed earlier.

For people who have experienced angioedema in connection with polyethylene glycol (PEG), an inactive ingredient in mRNA vaccines, there has been concern about whether vaccination is safe. A case series followed fifteen patients with confirmed or suspected PEG hypersensitivity, some of whom had previously experienced angioedema or anaphylaxis with PEG-containing products. All fifteen tolerated COVID-19 vaccination using a graded dose protocol, with only three experiencing mild, self-limiting symptoms that did not require epinephrine.¹⁴ The approach involved administering the vaccine in progressively larger portions under medical supervision, allowing the clinical team to stop early if a serious reaction began.

Children and Multisystem Inflammatory Syndrome

In children, COVID-19-related swelling tends to show up in an unexpected place. Multisystem inflammatory syndrome in children (MIS-C), a delayed inflammatory condition that follows SARS-CoV-2 infection, has been linked to retropharyngeal edema, which is swelling behind the throat. A case series documented three children with suspected MIS-C who had retropharyngeal edema without any sign of bacterial infection.¹⁵ This kind of swelling can be mistaken for a bacterial abscess and might lead to unnecessary antibiotic courses or even surgery if the COVID-19 connection is not considered.

For parents, the relevant symptom to watch for is a child who develops fever, neck stiffness, or difficulty swallowing several weeks after a known or suspected COVID-19 infection. MIS-C itself is rare, and retropharyngeal edema within MIS-C is rarer still, but it illustrates how broadly SARS-CoV-2 can disrupt the body’s fluid balance across different tissues and age groups.

People with Hereditary Angioedema During the Pandemic

Hereditary angioedema (HAE) is a genetic condition in which patients already have a deficiency in C1 esterase inhibitor, the same protein that SARS-CoV-2 may deplete. You might expect these patients to fare especially poorly during COVID-19, and some early pandemic commentary raised that alarm. The reality, based on the available data, has been more reassuring. A study comparing angioedema attack frequency and quality of life across pre-pandemic, pandemic, and post-pandemic periods in HAE patients found no statistically significant differences in most quality-of-life measures, including daily functioning, mood, nutrition, and overall scores.¹⁶

The one dimension that approached significance was fear, which is unsurprising given that HAE patients were told they might be at higher risk from a virus that attacks the same pathway underlying their condition. But in terms of actual attack frequency and severity, the pandemic did not reliably make HAE worse. This may be because HAE patients are already on prophylactic therapies that address bradykinin dysregulation, or because the mechanism by which SARS-CoV-2 disrupts the system does not stack onto the genetic deficiency in a straightforward additive way.

Recognizing Angioedema When COVID-19 Is Not the First Suspect

One of the trickier aspects of COVID-19-related angioedema is that it can be the presenting symptom before a patient even knows they have the virus. The case of the 57-year-old man on benazepril is a good example: he came in for tongue swelling and airway trouble, and the COVID-19 diagnosis came afterward.⁶ In settings where COVID-19 is circulating, unexplained angioedema without a clear allergic trigger should prompt testing for SARS-CoV-2, particularly in patients on ACE inhibitors or those from populations with higher baseline rates of angioedema.

The forensic literature has underscored the importance of this recognition. An analysis of deaths from angioedema and anaphylaxis in the context of COVID-19 highlighted that bradykinin-mediated angioedema carries a higher risk of progression to fatal airway obstruction than histamine-mediated forms, partly because it is slower to develop and may not trigger the urgency that a sudden allergic reaction does.⁸ The slower onset can be deceptive. A patient whose face is gradually swelling over hours may not get the same rapid escalation of care as someone in obvious anaphylactic shock, yet the airway risk can be just as severe or worse.

For anyone who experiences sudden facial swelling, lip swelling, tongue enlargement, or unexplained difficulty swallowing during or after a COVID-19 infection, the appropriate response is emergency medical evaluation. Mention the COVID-19 connection and any ACE inhibitor use upfront, because that context can steer the treating team toward the right category of treatment rather than defaulting to epinephrine and antihistamines alone.

1
PubMed Central. Dysregulated Bradykinin: Mystery in the Pathogenesis of COVID-19
2
PubMed Central. C1 esterase inhibitor and the contact system in COVID-19
3
PubMed Central. Angioedema in African American Patients Hospitalized for COVID-19
4
PubMed Central. Acquired Angioedema Post COVID-19 Infection: Can SARS-Cov-2 Induce Angioedema?
5
Otolaryngology Case Reports. Coronavirus disease-19 infection and angioedema in African Americans: A case series
6
PubMed Central. Angioedema, ACE inhibitor and COVID-19
7
PubMed Central. Angiotensin-Converting Enzyme (ACE) Inhibitor-Induced Angioedema in an African American Male With Coronavirus Disease 2019 (COVID-19)
8
PubMed Central. Deaths from Angioedema-Anaphylaxis and Covid-19
9
PubMed Central. Management of urticaria in COVID-19 patients: A systematic review
10
PubMed Central. Evaluation of the efficacy and safety of icatibant and C1 esterase/kallikrein inhibitor in severe COVID-19: study protocol for a three-armed randomized controlled trial
11
PubMed Central. Assessment of the myocardial effects of Bradykinin inhibitors by cardiac magnetic resonance (CMR) in discharged COVID-19 patients
12
eLife. A mechanistic model and therapeutic interventions for COVID-19 involving a RAS-mediated bradykinin storm
13
PubMed Central. Nonepisodic Angioedema with Eosinophilia Following Receipt of the BNT162b2 mRNA COVID-19 Vaccine
14
PubMed Central. Safety of COVID-19 vaccination in patients with polyethylene glycol allergy: A case series
15
PubMed Central. Multisystem inflammatory syndrome in children (MIS-C) and retropharyngeal edema: A case series
16
PubMed Central. Effect of COVID-19 on hereditary angioedema activity and quality of life