Why Am I Getting Sick So Often? Causes and When to See a Doctor

The short answer to why you keep getting sick so often is that your immune system is usually not broken. It is being undermined by a stack of ordinary things. The main culprits:

• Short sleep — the best-studied risk factor
• Chronic stress — keeps your defenses down
• Nutrition gaps — the raw materials your immune system runs on
• Dehydration and run-down basics
• High exposure — kids, travel, crowded workplaces

Most of the time, frequent illness is those factors compounding, and it's fixable. A smaller share reflects something medical, which is why “when to see a doctor” gets its own section below.

Short sleep measurably raises your odds of catching a cold. In a study of 164 healthy adults given cold-virus nose drops, those who slept under 5 hours a night in the week before had about 4.5 times the odds of developing a cold compared with those who slept more than 7 hours; 5 to 6 hours carried a similar risk (Prather et al., 2015). Sleep measured by a wrist tracker, not self-report, drove the result. Fragmented sleep, in that study, did not.

If you're getting sick constantly and also under-sleeping, start there before anything else.

Psychological stress raises infection risk in a dose-response pattern. In a classic trial, 394 healthy adults were deliberately exposed to cold viruses; the more stress they reported beforehand, the more often they developed a cold, from about 27% at the lowest stress levels to 47% at the highest (Cohen et al., 1991). Stress hormones, cortisol among them, help regulate immune activity, which is one proposed reason stressful stretches so often end in getting sick.

This is also where frequent illness connects to a bigger picture: the same chronic stress that runs your immune system down shows up as poor sleep and low energy too. We cover the stress side in depth in our guide to high cortisol and how to lower it.

Nutrition gaps matter for immune function because the immune system needs a steady supply of specific micronutrients, including vitamins A, C, D, E, B6 and B12, folate, zinc, iron, copper and selenium, and even a marginal deficiency may impair immunity (Gombart et al., 2020). That review was written partly by employees of a multivitamin maker, and it notes that the data on supplementing to prevent infection are contradictory. The practical point is narrower: chronic under-eating or a diet short on protein, fruit and vegetables can leave you deficient, and correcting a real deficiency is the goal. Megadosing a single "immune-boosting" supplement is not.

The evidence shows glutathione matters to immune cells, but it does not show that taking glutathione prevents infection in healthy people. Glutathione is the main antioxidant inside cells, and lymphocytes (a type of white blood cell) work best at a balanced, intermediate glutathione level. Even moderate shifts in that level change how lymphocytes behave (Dröge & Breitkreutz, 2000).

One limit worth stating plainly, since we sell glutathione: a review of glutathione and immune function found that lymphocytes in healthy people already sit at an optimal glutathione level on average, and found no indication that giving glutathione or its precursor cysteine enhances resistance to infection in healthy people (Dröge & Breitkreutz, 2000). The benefit in that review was confined to diseases that cause a genuine cysteine and glutathione deficiency. If you are healthy and getting sick often, the fundamentals above are the evidence-based fix. Protocol MD's physician-prescribed glutathione is compounded and not FDA-approved, and it is not a treatment for frequent infections.

Sometimes you're getting sick often simply because you're exposed often — young kids in daycare, frequent travel, a crowded workplace, a new city with new germs. That's not an immune failure; it's math. Basic hygiene (handwashing, not touching your face), reasonable distance from obviously sick people, and staying current on recommended vaccinations do more here than any supplement. If your exposure genuinely spiked and then you started getting sick more, that's often the whole explanation.

Some frequent illness has a medical cause, and that is when it warrants a doctor's visit. It's worth a physician's evaluation if you're getting frequent, severe, or unusually persistent infections — for example, infections that are hard to shake, keep recurring in the same place, or seem out of proportion to your exposure.

Persistent, unexplained frequent illness can occasionally reflect an underlying condition a physician can identify and address, and that's not something to self-diagnose from an article. If your pattern feels excessive and it isn't explained by an obvious cause like sleep, stress, or a houseful of sick kids, get evaluated rather than keep guessing.

The bottom line is that getting sick often usually means a normal immune system is being undermined, not that it is failing. Work the fundamentals first, in order: protect your sleep, manage chronic stress, eat enough real food, stay hydrated and practice basic hygiene, and give them a few consistent weeks. If you are still getting sick constantly after that, see a physician rather than adding another supplement.