Medically Reviewed by Hansa D. Bhargava, MD
Lack of Sleep
Not getting enough sleep can make you more likely to catch viruses or germs. And you also may take longer to get better. That’s because your body can’t make as many infection-fighting cells and proteins called antibodies that help defend against illness. Your body releases certain proteins that help the immune system, called cytokines, only during sleep.
Anxiety
Stress and worry aren’t great germ fighters. Just having anxious thoughts can weaken your immune response in as little as 30 minutes. Constant stress takes an even bigger toll and makes it harder to fend off the flu, herpes, shingles, and other viruses. Talk to your doctor if you can’t shake your worry or if it gets in the way of normal life.
Low Vitamin D
You may know you need it for strong bones and healthy blood cells. But vitamin D also helps boost your immune system. You can get it in eggs, fatty fish, and fortified foods like milk and cereal. Sunlight is another key source. In the summer, just 5-15 minutes of rays on your hands, face, and arms 2-3 times a week usually is enough. In the winter, you might need a bit more.
Certain Medications
They include drugs to treat allergies, arthritis, lupus, IBS, and organ transplant. Corticosteroids are one example, as are TNF inhibitors for inflammation and chemotherapy for cancer. Talk with your doctor before you adjust any prescription medication.
Too Few Fruits and Veggies
These foods may help your body make more of the white blood cells you need to fight off infections. Fresh produce and nuts and seeds pack a lot of zinc, beta-carotene, vitamins A, C, and E, and other nutrients you need for a healthy body. Plant-based foods also fill you up with fiber, which helps lower your body fat percentage, which can strengthen your immune response.
Marijuana
Smoke from pot can inflame your lungs. If you use it regularly, you may have the same breathing problems you can get from nicotine cigarettes. That means coughing up colored mucus called phlegm and a higher chance of lung infections.
High-Fat Diet
Oils can hinder germ-fighting white blood cells. And high-fat diets over time can upset the balance of bacteria in your gut that can help immune response. Look for low-fat dairy with no added sugar, along with lean protein like seafood, turkey, and chicken, or lean cuts of beef with any visible fat cut off. Also, being obese seems to make you more likely to get the flu and other infections, like pneumonia.
Too Little Time Outdoors
Sunlight may energize special cells in your immune system called T-cells that help fight infection. But being outside brings other benefits, too. Many plants in the woods make phytoncides and other substances you breathe in that seem to bolster your immune function.
Smoking
Nicotine from cigarettes, chewing tobacco, or any other source can weaken your body’s ability to fight germs. Yes, vaping counts, too. And it’s not just the nicotine. Other chemicals in e-liquids seem to suppress your immune response, especially when you inhale them through vaping.
Alcohol
Just overdoing it once slows your body’s ability to fight germs for up to 24 hours. Over time, drinking too much blunts your body’s ability to repair itself. That may be part of the reason you’re more likely to get illnesses like liver disease, pneumonia, tuberculosis, and certain cancers. If you use alcohol, try to keep it to one drink a day for women and two drinks for men.
Grief
There is some evidence that sorrow, especially if lasts a long time, can depress your body’s immunity. The effect can linger for 6 months but may go on longer if your grief is deep or doesn’t ease. Talk to your doctor or a mental health professional if you need help with a loss or traumatic event.
Lack of Exercise
Regular aerobic exercise appears to help your body fight illness caused by viruses and bacteria. That’s in part because it helps the blood get around your body more efficiently, which means germ-fighting substances get where they need to go. Scientists continue to study exactly how exercise helps boost your immune system.
No Sex
Good news! Weekly intimacy seems to help boost your immune system compared to those who have it less often. Sex raises levels of a germ-fighting substance called Immunoglobulin A, or IgA. But more may not always be better. Couples who had sex more than twice a week had lower levels of IgA than those who had no sex at all.
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis, or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on this site. If you think you may have a medical emergency, immediately call your doctor or dial 911.