Yes, you can take vitamin C with losartan. There are no known drug interactions between the two, and clinical trials studying blood pressure have routinely allowed participants to take vitamin C supplements while on antihypertensive medications like losartan. That said, there are a few details worth understanding about how these two substances overlap in your body.
No Direct Interaction on Record
Major drug interaction databases, including Drugs.com, list no interactions between losartan and vitamin C. This means vitamin C is not expected to change how your body absorbs, processes, or eliminates losartan, and losartan should not interfere with vitamin C absorption either.
In animal research, vitamin C and losartan have been given together to study their combined effects on kidney protection. While the combination wasn’t more effective than either substance alone for that purpose, the studies did not flag safety concerns from co-administration. The pairing simply didn’t offer added benefit in that specific context.
Both Affect Blood Pressure, but Differently
Here’s where things get interesting. Losartan works by blocking receptors that a hormone called angiotensin II uses to tighten blood vessels. When those receptors are blocked, your vessels relax and blood pressure drops. Vitamin C, it turns out, works on a related but earlier step in the same system. Research in hypertensive rats found that vitamin C reduced the production of the enzyme (ACE) that creates angiotensin II in the first place. Vitamin C has also been shown to decrease the binding strength of angiotensin II to the very receptors that losartan blocks.
In practical terms, this means vitamin C and losartan both nudge blood pressure downward, but through different mechanisms in the same pathway. A large meta-analysis of 29 randomized controlled trials found that vitamin C supplementation modestly lowers blood pressure. Fifteen of those trials included people already taking blood pressure medications, so the combination has been studied in real patients without raising red flags.
The blood pressure effect of vitamin C is generally small, so the risk of your pressure dropping too low from adding a supplement is minimal. But if you already run on the lower side or feel dizzy on losartan, it’s worth monitoring your readings when you start vitamin C.
Kidney Considerations at High Doses
Losartan is commonly prescribed to protect kidney function in people with high blood pressure or diabetes. Vitamin C at normal doses poses no known risk to the kidneys. However, very high doses of vitamin C (well above the recommended daily amount of 65 to 90 mg for most adults) can increase oxalate levels in urine, which may stress the kidneys over time.
If you’re taking losartan specifically for kidney protection, sticking to moderate vitamin C doses is a reasonable approach. Clinical trials in blood pressure research have used doses ranging from 60 mg to 4,000 mg per day. The upper tolerable limit for adults is 2,000 mg per day, beyond which digestive side effects like nausea and diarrhea become common. For most people, 200 to 500 mg daily provides the full antioxidant benefit without unnecessary risk.
Timing and Practical Tips
There’s no evidence that you need to separate these two by time of day. You can take them together at breakfast or at different times, whichever fits your routine. Losartan can be taken with or without food, and vitamin C is well absorbed either way, though taking it with a meal can reduce the chance of stomach upset at higher doses.
If you take other supplements alongside vitamin C, those are worth checking separately. Potassium supplements, for instance, can be a concern with losartan because the drug raises potassium levels on its own. Vitamin C does not share this effect, which is one reason the combination is considered safe.
Who Should Pay Extra Attention
People with existing kidney disease, those on dialysis, or anyone with a history of kidney stones should be more cautious with vitamin C supplementation in general, not because of a specific interaction with losartan, but because impaired kidneys handle oxalate less efficiently. If you fall into one of these groups and want to supplement, lower doses (under 250 mg) are a safer starting point.
For most people taking losartan for high blood pressure, a standard vitamin C supplement is perfectly fine to add to your daily routine. The two substances work on overlapping biological pathways without interfering with each other, and the combination has been used in clinical research without documented problems.