Losartan and losartan potassium are the same medication. Every losartan tablet you pick up at a pharmacy contains losartan potassium as the actual ingredient. The two names refer to different parts of the same molecule: “losartan” is the active portion that lowers your blood pressure, while “losartan potassium” is the complete chemical form used to manufacture the tablet.
Why Two Names Exist
Many medications are manufactured as “salt forms,” meaning the active drug molecule is paired with another element to make it more stable or easier for your body to absorb. In this case, losartan is paired with potassium to create losartan potassium, the version that actually goes into the tablet. This is extremely common in pharmaceuticals. Metformin hydrochloride, sertraline hydrochloride, and lisinopril dihydrate all follow the same pattern.
Under naming rules set by the United States Pharmacopeia, drug labels typically use the name of the active portion rather than the full salt name. So a prescription bottle might say “losartan 50 mg” even though the tablet physically contains losartan potassium. The FDA requires that the full salt name still appear somewhere on the label and packaging, which is why you’ll see “losartan potassium” in the fine print, on the manufacturer’s fact sheet, or in your pharmacist’s drug information printout. The brand-name version, Cozaar, officially lists “losartan potassium” as its active ingredient.
The 50 mg strength listed on your bottle refers to the losartan portion specifically, not the total weight of losartan potassium. This distinction matters only to chemists. For you, it means the dose on your label is already calibrated to the part of the molecule doing the work.
How Much Potassium Is in Each Tablet
Because the word “potassium” appears in the name, some people wonder whether the tablet is a meaningful source of dietary potassium. It isn’t. A 50 mg losartan potassium tablet contains about 4.24 mg of elemental potassium. For context, a single banana has roughly 422 mg. Even the 100 mg tablet delivers only about 8.48 mg of potassium, a nutritionally negligible amount.
That said, losartan itself can raise your potassium levels through a completely separate mechanism. As a blood pressure drug in the ARB class (angiotensin II receptor blockers), it affects how your kidneys handle potassium. This pharmacological effect is far more significant than the trace potassium in the tablet. The risk goes up if you also take potassium supplements, potassium-sparing diuretics, or certain other blood pressure medications. Periodic blood work to check potassium levels is standard for people on this drug, especially early in treatment or after a dose change.
How Losartan Works in Your Body
Once you swallow the tablet, the potassium portion splits off and the losartan molecule gets to work. It blocks a receptor (called AT1) that a hormone uses to tighten blood vessels. By blocking that receptor, losartan keeps your blood vessels more relaxed and your blood pressure lower.
Your liver also converts some of the losartan into a secondary compound called E-3174, which is roughly 10 to 40 times more potent at blocking the same receptor. This conversion depends on a specific liver enzyme. Some people carry genetic variations that make this enzyme less efficient, which can affect how well the drug works. If losartan doesn’t seem to be controlling your blood pressure adequately, this metabolic variation is one possible explanation your prescriber might consider.
Available Strengths and Typical Use
Losartan potassium tablets come in 25 mg, 50 mg, and 100 mg strengths. The standard starting dose for high blood pressure is 50 mg once daily. It’s also prescribed for kidney protection in people with type 2 diabetes and for reducing stroke risk in certain patients with an enlarged heart. A combination tablet that pairs losartan potassium with hydrochlorothiazide (a diuretic) is available for people who need additional blood pressure control.
What This Means for Your Prescription
If your prescription says “losartan” and your bottle says “losartan potassium,” or vice versa, you’re looking at the same drug at the same dose. Generic and brand-name versions all contain losartan potassium. No pharmacy has ever stocked a losartan tablet that wasn’t the potassium salt form. The naming difference is purely a labeling convention, not a clinical one.