Anemia: Causes, Types, and How Medications Affect Your Red Blood Cells

When your body doesn’t have enough anemia, a condition where your blood lacks sufficient healthy red blood cells to carry oxygen to your tissues. Also known as low hemoglobin, it’s one of the most common blood disorders worldwide—and often overlooked until you’re exhausted, pale, or out of breath climbing stairs. It’s not a disease itself, but a sign something else is wrong. Your red blood cells need iron, vitamin B12, or folate to make hemoglobin, the protein that grabs oxygen. If any of those are missing, your cells shrink, weaken, or die off faster than your body can replace them.

There are many kinds of anemia, and each has a different cause. iron deficiency, the most common form, happens when you don’t get enough iron from food or lose too much through bleeding. Think heavy periods, ulcers, or even daily aspirin use. Then there’s vitamin B12 deficiency, often tied to gut problems like Crohn’s, gastric bypass, or just poor absorption as you age. Some people don’t make intrinsic factor—the protein your stomach needs to absorb B12—and that leads to pernicious anemia. And then there’s anemia from chronic disease, like kidney failure or cancer, where your body just stops making enough red blood cells, even if nutrients are fine.

Medications play a big role—both in causing and treating anemia. Drugs like proton pump inhibitors (PPIs) for acid reflux can block iron absorption over time. Metformin, used for diabetes, is linked to lower B12 levels. Even some antibiotics and chemotherapy drugs can crush your bone marrow’s ability to produce new blood cells. On the flip side, iron pills, B12 shots, and erythropoietin (EPO) injections are common fixes. But here’s the catch: taking supplements without knowing the cause can hide the real problem. A simple blood test can tell you if your anemia is from low iron, low B12, or something deeper.

You’ll find posts here that dig into how common meds like furosemide, hydrochlorothiazide, and even antivirals can affect your blood counts. Others show how supplements like biotin can mess with lab results, making anemia look worse—or better—than it is. There’s also advice on what to ask your doctor when your hemoglobin drops, and how to tell if your fatigue is just stress or a sign your red blood cells are failing.