Kounis Syndrome: Could a Simple Allergy Trigger a Heart Attack?

We usually think of allergies as something that causes a rash, a sneeze, or maybe some swelling — annoying, yes, but manageable. But what if an allergic reaction could affect your heart?

That’s the question many people are now asking after the sudden passing of businessman Sanjay Kapur. Early reports suggest that an allergic reaction may have led to a cardiac event, putting a rare condition called Kounis Syndrome in the spotlight.

It’s not something you hear about every day, but it’s real—and worth knowing about. 

What is Kounis syndrome?

Kounis Syndrome is a rare condition where an allergic reaction affects the heart. It can also affect arteries in other organs, like mesentric ischemia (abdominal artery) or brain infarcts.

It’s sometimes called “allergic angina” or “allergic heart attack.”

When you're exposed to something you're allergic to — like a food, insect sting, or medication — your body releases chemicals like:

• Histamines
• Cytokines
• Leukotrienes

These can cause:

• Spasm and narrowing of the arteries 
• Plaque rupture
• Or even the development of clots

All of this can reduce blood flow to your heart. That’s when symptoms like chest pain, breathlessness, or even a heart attack can happen.

What causes it?

Kounis Syndrome usually begins with an allergic reaction. Common triggers include:

• Certain medications
• Insect stings or bites
• Foods like nuts, seafood, or dairy
• Environmental allergens such as pollen or latex
• Contrast dyes used during medical scans

Once exposed, the body releases a surge of chemicals aimed at fighting the allergen, but in Kounis Syndrome, they also affect the heart.

What does it feel like?

The symptoms can look like a combination of a heart problem and an allergic reaction:

• Chest pain or tightness
• Shortness of breath
• Rashes, hives, or flushing
• Swelling of the face or lips
• Dizziness or fainting
• Nausea or discomfort

These usually begin within minutes to an hour after allergen exposure. If the person already has heart disease, symptoms may be more severe.

Who can get it?

There are three types of Kounis syndrome, depending on your heart health:

• Type I: Happens in people with no previous heart disease. The allergic reaction alone causes an artery spasm.

• Type II: Occurs in people with known heart disease. The allergic reaction can worsen an existing blockage.

• Type III: Occurs when a previous heart procedure or implant is involved. Sometimes, the body can react to materials used in that implant—like metal or coatings. If an allergic reaction is triggered, it can cause clotting around the implant, which may reduce blood flow to the heart.

How do doctors diagnose it?

Since Kounis Syndrome sits at the crossroads of an allergy and a heart issue, here's what they usually check:

• Your symptoms — especially if chest pain or tightness appears during or after an allergic reaction
• Your vital signs — like heart rhythm and blood pressure
• Blood work — to look for signs of stress on the heart or a strong immune response
• Scans or imaging — to check how well blood is flowing to the heart
• Allergy history — including recent exposures to foods, bites, or medications

How Is It Treated?

Kounis Syndrome needs fast action because it involves both an allergic reaction and the heart. Here's what happens — and what you can do if you're ever in that situation.

What to do immediately:

If someone develops chest pain, breathlessness, or faints during or after an allergic reaction:

• Call emergency services right away
• Keep the person calm and seated or lying down
• Loosen tight clothing
• If they have an emergency allergy kit, help them use it
• Don’t delay medical care — even if the symptoms seem to improve

What doctors will do:

At the hospital, the team will:

• Work to ease the allergic reaction
• Protect the heart and restore blood flow
• Monitor heart and breathing closely

Long-term prevention:

• Know your allergy triggers
• Keep emergency action plans or kits handy
• Tell healthcare providers about any past reactions, especially before procedures

Kounis Syndrome may be rare, but it’s a good reminder to listen to your body — especially when symptoms don’t follow the usual script. A little caution is key!