Your immune system works quietly every day, protecting your body from harmful germs and helping you recover from illness. Most of the time, we barely think about it. But sometimes, our bodies begin showing changes that deserve a closer look. Perhaps you’re catching infections more frequently than usual, feeling exhausted despite getting enough sleep, or noticing that small cuts take longer to heal. These symptoms can be easy to dismiss as stress, aging, or simply having a difficult week.

While occasional tiredness or a common cold doesn’t automatically mean your immune system is weak, certain persistent patterns may signal an underlying health problem. Doctors pay particular attention to infections that keep returning, illnesses that are unusually severe, and symptoms that don’t improve as expected. Digestive problems, unexplained swelling, and recurring mouth infections can also warrant investigation, although they have many possible causes.

There are seven important changes worth recognizing, and some are easier to overlook than you might think.

Continue below in Part 2.