What Is an Overactive Immune System? (2024)

Your immune system is a fascinating, interconnected network. It protects you from millions of harmful bacteria, microbes, viruses, toxins and parasites just waiting to invade the openings of your mouth and nose and any break in your skin.

If these unwelcome intruders do get inside your body, your immune system goes to work, sending out lines of defense — in your blood, organs, muscles or bones.

Your immune system is vital to life, but sometimes, it can get overzealous. And that’s when problems can start.

Rheumatologist Leonard Calabrese, DO, explains what can cause your immune system to go into overdrive and offers advice on how to manage things if it does.

What is an overactive immune system?

An overactive immune system means your body can’t tell the difference between the good guys (healthy cells) and the bad guys. So, it overreacts, attacking and damaging healthy tissues by mistake. And it may even keep attacking after getting rid of the invader.

Having an allergic reaction to normally harmless things (allergens), like dust, mold, pollen, pet dander or certain foods, is common if you have an overactive immune system. Examples include:

• Asthma: Your airways get narrow or swollen and are blocked by too much mucus, which can make you cough, wheeze and have trouble breathing.
• Eczema: You get dry and itchy patches of skin.
• Allergic rhinitis (hay fever): Causes sneezing, runny, itchy nose and watery eyes.

“In many cases, an immune system that overreacts is as harmful and dangerous as one that stops working,” clarifies Dr. Calabrese. “Basically, it means your immune system has turned against you.” And that can lead to serious autoimmune conditions.

Autoimmune conditions and overactive immune systems

According to Dr. Calabrese, an overactive immune system can contribute to many different autoimmune conditions. The most common are:

• Rheumatoid arthritis (RA): Your immune system attacks your joints, leading to inflammation, redness, pain and stiffness. Over time, this can cause your joints to be misshapen and difficult to move.
• Multiple sclerosis (MS): Your immune system destroys the fatty layer that surrounds and protects your nerves from damage. Without it, you’re vulnerable. As MS progresses, it attacks your brain, spine and eyes. This causes problems with your balance, muscle control, vision and other bodily functions.
• Celiac disease: With this condition, when you eat gluten (a protein found in wheat, barley, rye and other grains), your immune system attacks your small intestines, damaging the finger-like projections (villi) that help your body absorb nutrients.

Other autoimmune conditions include:

• Lupus (affects your skin, joints and blood cells).
• Vasculitis (affects your blood vessels).
• Sjögren’s syndrome (causes dry eyes and dry mouth).
• Inflammatory bowel disease (affects your digestive tract).
• Chronic fatigue syndrome (causes excessive exhaustion, headaches, joint and muscle pain).

Causes of an overactive immune system

Doctors still don’t know exactly why the immune system sometimes fails. But there are clues to how it happens.

“The immune system is an integrated network that’s hard-wired into your central nervous system,” explains Dr. Calabrese. “So, when it’s healthy, everything works automatically. But things go haywire when the system starts to crumble. For example, if you don’t sleep well and get stressed out, your body will produce more of the stress hormone cortisol.

“Over time, high cortisol levels can have a degenerative effect on your body. Healthy bone and muscle break down and slow the healing process. Cortisol can interfere with digestion and metabolism, as well as adversely affecting your mental functions.”

Signs of an overactive immune system

If your immune system is working overtime, you may have one or more of these symptoms:

• Fatigue.
• Unexplained fever.
• Unexplained weight loss.
• Drenching night sweats.
• Itchy skin.
• Sore, aching muscles.
• Fingers or toes that tingle or are numb.
• Trouble focusing.
• Hair loss.
• Inflammation, rashes or redness anywhere on your body.
• Swollen lymph nodes in your neck, armpits or groin.

Normalizing an overactive immune system

Depending on what type of symptoms you’re having, your provider may recommend medications for pain, skin rashes, trouble sleeping, depression and anxiety, among others. Lifestyle changes may also help.

“Though we don’t always know exactly why an immune system fails, we do know that adopting healthy habits can help keep your immune system ticking along well,” Dr. Calabrese says.

Some of the best habits for a healthy lifestyle include:

• Eating nutritious foods.
• Getting regular exercise.
• Keeping a weight that’s healthy for you.
• Catching enough ZZZs.
• Staying up to date on vaccines.
• Managing stress.

These steps support good cardiovascular health and can contribute to a healthy immune system.