Hereditary angioedema (HAE) attacks can sometimes feel like they come out of nowhere. However, some people notice early warning signs before swelling starts.

Learning to recognize these early signs may help you act sooner and talk with your doctor about your treatment plan. This article explains the signs that may occur before an HAE attack and what to do if you notice them.

What Happens Before an HAE Attack?

Prodromes, also called prodromal symptoms, are early warning signs that can happen before an HAE attack starts. They may appear hours before an attack, and some people notice them days in advance.

🗳️ Which hereditary angioedema (HAE) symptom do you notice most?

Fatigue or low energy

Nausea or stomach pain

Tight or tingling skin

A nonitchy rash

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Some people with HAE use these signs to recognize when swelling may be starting. However, not every attack has clear early warning signs.

In a survey of 208 people with HAE, about 60 percent said they noticed early warning signs before a swelling attack.

What Signs Indicate an Attack May Be Coming?

Early warning signs can be subtle and easy to miss. You may not connect them to HAE until you notice a pattern over time.

The signs vary from person to person, but these are some of the most commonly reported:

Fatigue and Low Energy

Feeling unusually tired is one of the most commonly reported early signs of an HAE attack. In the survey mentioned above, 64 percent of the participants reported tiredness or fatigue before an attack.

This may feel like being sluggish, drained, or low on energy, even after a normal amount of sleep. Fatigue can also make it challenging to get work done or complete daily activities.

Mood Changes

Some people notice shifts in their mood in the hours or days before an HAE attack. This can include increased irritability, anxiety, or a low mood that feels out of character.

Feeling ‘Off’

“Malaise” is a term for a general feeling of being unwell. It may be hard to describe exactly what’s wrong, other than feeling like something is off. Feeling uneasy, ill, or weak could be a sign that a HAE attack is coming.

Nausea

When HAE swelling affects the stomach or gastrointestinal tract, it can cause nausea, diarrhea, vomiting, and abdominal pain.

For some people, nausea or stomach pain can be an early indication of an HAE attack. In the survey of 208 people with HAE, about 50 percent reported stomach pain or abdominal pressure before swelling starts.

Muscle or Joint Pain

Some people notice muscle aches or joint pain before an HAE attack begins. This discomfort may feel like general soreness before any swelling appears.

Tight or Tingling Skin

A feeling of tightness, pressure, or tingling in a specific area on the skin may be a sign that swelling will develop there later.

Unusual Rash

One of the most important early signs is a type of rash called erythema marginatum. It usually appears as discolored, ring-shaped patches on the arms, legs, or trunk. Erythema marginatum usually doesn’t appear on the face, palms of the hands, or soles of the feet.

The rash typically isn’t itchy or painful like hives, so it can sometimes go unnoticed. It may also disappear and come back within hours. About one-third of people with HAE experience erythema marginatum before swelling starts.

How Early Can Prodromes Start?

The timing of prodromes can vary widely. For some people, they provide warning signs hours or even days before a swelling attack.

Prodromes often begin hours before an attack. In the survey, 27 percent of people noticed prodromes two to six hours before swelling, while 29 percent had prodromal symptoms more than six hours before swelling.

How Can You Tell a Warning Sign From an Attack?

Knowing the difference between an early warning sign and an HAE attack may help you decide what to do next.

Early warning signs are usually milder. You might feel tired, achy, or nauseated or notice tightness, tingling, or a nonitchy rash.

During an attack, symptoms are usually more severe and may include visible swelling, more pain, or trouble moving or using the affected body part.

One simple way to think about it: Early warning signs happen before swelling starts. An HAE attack is when swelling is already happening.

How Does HAE Differ From an Allergic Reaction?

It can be easy to confuse HAE symptoms, especially swelling, with an allergic reaction, but they’re different conditions.

HAE usually doesn’t involve itching, whereas allergic reactions often do, especially when hives are present. Although some people develop a rash as a prodromal symptom, it’s different from the hives caused by an allergic reaction.

Allergic reactions are often treated with antihistamines, corticosteroids, or epinephrine, depending on how severe they are. However, these medications don’t treat HAE attacks.

Any throat swelling or trouble breathing is a medical emergency, whether it’s caused by HAE or an allergic reaction.

Why Does Tracking Prodromes Matter?

Noticing patterns in your early symptoms can make a real difference. Studies show that many people with HAE can predict an attack based on prodromes and take action sooner.

Tracking your early symptoms can help you:

• Recognize your personal warning signs
• Know how much time you typically have before swelling starts
• Decide when to use on-demand treatment

Keeping a symptom journal or diary can help. Try to keep track of what happens before and during each attack, including your symptoms and possible triggers. These may include emotional stress, physical activity, surgery, dental work, estrogen-containing birth control, or medications such as ACE inhibitors.

Steps To Take Before Swelling Starts

If you notice prodromal symptoms, it’s important to act early by following your HAE care plan.

• Follow your written HAE action plan — Many people with HAE have a personalized plan that outlines what to do to help reduce the severity and frequency of attacks.
• Consider on-demand treatment — If you’ve been prescribed an on-demand treatment, use it as early as possible when symptoms begin, according to your doctor’s instructions.
• Contact your healthcare team — Reach out to your doctor if your prodromes are new or changing or if your symptoms are more severe than usual.

Know When To Seek Emergency Help

If you notice any of the following symptoms, seek emergency care or call 911 immediately. These can be signs of throat or airway swelling, which can be life-threatening:

• Throat tightness
• Trouble swallowing
• Tongue swelling
• Trouble breathing

Getting Ahead of HAE Attacks

HAE attacks don’t always start without warning. Some people notice early signs, such as fatigue, mood changes, nausea, muscle aches, or a nonitchy rash, before swelling begins.

Learning your own pattern may help you act sooner and feel more prepared. These signs don’t happen before every attack, but they can provide helpful clues.

Join the Conversation

On myHAEteam, people share their experiences with hereditary angioedema, get advice, and find support from others who understand.

Have you noticed any early warning signs before an HAE attack starts? Let others know in the comments below.