Your immune system is your body’s first-line defense against invaders like germs. It helps protect you from getting sick and promotes healing when you’re unwell or injured. You can strengthen your immune system by eating nutritious foods, exercising and getting enough sleep.
Your immune system is a large network of organs, white blood cells, proteins and chemicals. These parts all work together to protect you from germs and other invaders. Your immune system also helps your body heal from infections and injuries.
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Your immune system works hard to keep you healthy. It does this by:
Invaders your immune system protects you against include:
When your immune system is working properly, it:
But things don’t always go this smoothly. Sometimes, your immune system doesn’t work properly. For example, it may be too weak to fight off invaders, or it may launch too strong of a response.
Many different conditions can weaken your immune system and make you more susceptible to infection. Conditions at birth are less common than those that develop later in life, like Type 2 diabetes and cancer.
At the other end of the spectrum, your immune system may react too strongly to invaders (real or perceived). It may mount an attack when there’s no invader. Or it may keep attacking after getting rid of an invader. An overactive immune system can lead to problems like autoimmune diseases or allergic reactions.
Many parts of your body, including immune system organs and cells, work together to keep you healthy. The main components of your immune system are:
Innate immunity is protection that you’re born with. Your innate immune system is part of your body’s first-line defense. It responds to invaders right away by attacking any organism that shouldn’t be in your body. It doesn’t need prior training to tell the difference between cells that belong in your body and those that don’t.
The white blood cells involved in innate immunity don’t learn to recognize certain invaders. They also have no memory of attacking invaders and don’t offer protection against specific germs (or the infections they cause) in the future.
That’s where acquired immunity comes into play. Acquired immunity, also called adaptive or specific immunity, is protection your body gains (acquires) over time from exposure to germs. Certain white blood cells called lymphocytes remember specific invaders and can tell when they don’t belong in your body. So, if those invaders try to get in again, the lymphocytes can quickly spring into action and work with other cells to eliminate the threat.
Vaccines support your acquired immunity by training its cells to identify and destroy invaders before they make you sick.
Conditions that can interfere with the normal workings of your immune system include:
Signs and symptoms vary depending on the condition and may include:
Healthcare providers often use blood tests to check how well your immune system is working. Specific blood tests your provider may order include:
Some medications do important work in your body but in the process, can weaken your immune system. These include:
If you need any of these treatments, talk to your healthcare provider about how you can support your immune system.
No one likes getting sick, and it’s common to wonder how to improve or strengthen your immune system. Because your immune system is complex, there’s no fast and easy answer that works for everyone on how to build it up. That’s why it’s important to talk to a healthcare provider. They can give you individualized advice based on your medical history. They’ll also talk to you about your lifestyle and daily habits to see what changes you can make.
Here are some general tips to keep your immune system running smoothly:
Many different medical conditions, medications and lifestyle factors can weaken your immune system and prevent it from defending you as well as it should. If you feel like you’re always sick or have symptoms that never go away, make an appointment with a healthcare provider. They’ll determine if you have a weak immune system and what’s causing the issue.
Like a home security system that guards against intruders and sounds the alarm when needed, your immune system is on-call and ready to signal for help when it perceives a threat. The cells and organs of your immune system work together to locate, identify and remove germs and other invaders to keep you safe and healthy. But guarding isn’t your immune system’s only duty. Its crew also heals the damage that intruders cause, just like you’d need someone to repair a broken window or door.
But even the best security system can malfunction sometimes. Autoimmune diseases or other conditions can disrupt your body’s ability to defend itself against intruders or repair damage. That’s why it’s important to see a healthcare provider regularly for checkups. They can find problems early and, if needed, provide treatment to keep your immune system working at its best.
Last reviewed by a Cleveland Clinic medical professional on 10/20/2023.
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