Several common supplements can lower blood pressure enough to cause symptoms, especially if you’re already taking blood pressure medication or naturally run on the lower side. Potassium, magnesium, omega-3 fish oil, garlic extract, beetroot juice, and certain herbal supplements all have documented blood-pressure-lowering effects ranging from a few points to over 10 mmHg. A drop of just 20 mmHg can be enough to make you dizzy or faint.
Potassium
Potassium is one of the most powerful blood-pressure-lowering supplements available without a prescription. A meta-analysis of clinical trials found that potassium supplementation reduced systolic pressure (the top number) by about 4.5 mmHg and diastolic pressure (the bottom number) by about 3 mmHg. The effect is strongest in people who eat a lot of sodium, aren’t on blood pressure medication, and have low potassium intake to begin with.
Potassium works partly by helping your kidneys flush out excess sodium and partly by relaxing blood vessel walls. If you’re supplementing potassium while also eating potassium-rich foods like bananas, potatoes, and leafy greens, the combined effect can be significant. People on certain blood pressure medications, particularly ACE inhibitors, need to be especially cautious because these drugs already raise potassium levels.
Magnesium
Magnesium lowers blood pressure through several pathways. It relaxes blood vessel walls by blocking calcium from tightening smooth muscle cells, supports the production of nitric oxide (a molecule that dilates blood vessels), and helps regulate the nervous system signals that control vascular tone. It also influences aldosterone, a hormone that controls how much sodium and water your kidneys retain.
In trials involving people with high blood pressure and diabetes, magnesium supplementation lowered systolic pressure by about 5.8 mmHg and diastolic by 2.5 mmHg. That’s a meaningful drop, comparable to some low-dose prescription medications. Magnesium also affects potassium balance in the body, so its blood-pressure-lowering effect can compound with potassium supplementation.
Garlic Extract
Aged garlic extract is one of the better-studied supplements for blood pressure. A meta-analysis of 12 trials involving over 550 people with high blood pressure found that garlic supplements lowered systolic pressure by about 8.3 mmHg and diastolic by about 5.5 mmHg. Those numbers rival some first-line blood pressure drugs. The active compounds in garlic promote the production of hydrogen sulfide, which relaxes blood vessels.
Dosages in clinical trials ranged from 600 to 2,400 mg per day of garlic powder, delivering roughly 8 to 31 mg of allicin (the key active compound). If you’re taking garlic supplements alongside prescription blood pressure medication, the combined effect could push your pressure lower than intended.
Beetroot Juice
Beetroot juice contains high levels of dietary nitrates, which your body converts into nitric oxide. This molecule signals blood vessels to widen, reducing pressure. The effect is fast: blood pressure typically drops within 2 to 3 hours of drinking beetroot juice, and the reduction can be substantial.
In acute studies, systolic pressure dropped anywhere from 4 to 22 mmHg depending on the dose and the individual. One trial found a 7.7 mmHg drop that persisted at the 4-week mark with daily consumption. The strongest effects tend to happen in the first few hours, but regular intake over two weeks or more produces more consistent results than shorter periods. For someone whose blood pressure is already normal or low, these drops could easily push readings into symptomatic territory.
Omega-3 Fish Oil
Fish oil supplements containing EPA and DHA lower blood pressure in a dose-dependent way. At doses between 1 and 2 grams per day, systolic pressure drops by about 1.8 mmHg with no significant effect on diastolic. At 3 to 4 grams per day, the effect roughly doubles: systolic drops by nearly 4 mmHg and diastolic by about 1.9 mmHg.
These numbers are modest on their own, but fish oil is one of the most commonly taken supplements in the world. Many people take it alongside other supplements on this list without realizing the effects stack. The blood pressure reduction is strongest in people with high blood pressure who aren’t on medication, but it still occurs in those with normal readings.
L-Arginine
L-arginine is an amino acid that serves as the raw material your body uses to make nitric oxide. Inside the cells lining your blood vessels, an enzyme converts L-arginine into nitric oxide, which then signals the surrounding muscle to relax and the vessel to widen. This lowers the resistance your heart pumps against, reducing blood pressure.
The blood-pressure-lowering effect requires relatively high doses, but L-arginine is widely available as a standalone supplement and is also found in many pre-workout formulas. If you’re combining a pre-workout containing L-arginine with beetroot juice (another nitric oxide booster), the vasodilating effects can stack considerably.
Hibiscus Tea and Extract
Hibiscus is often overlooked as a casual herbal tea, but its blood-pressure-lowering effect is surprisingly potent. In one head-to-head trial, hibiscus extract performed comparably to lisinopril, a widely prescribed blood pressure medication. Hibiscus brought blood pressure to normal levels in 76% of participants, while lisinopril achieved this in 65%. Both reduced a key marker of the blood pressure regulation system (plasma aldosterone) by roughly 30 to 32%, with no significant difference between them.
Hibiscus also acted faster in some measures, producing significant systolic reductions by week 2, while lisinopril reached significance at week 4. This was a small study in people with mild to moderate high blood pressure, so the results don’t mean hibiscus replaces medication. But they do show that drinking concentrated hibiscus tea or taking hibiscus supplements can meaningfully lower blood pressure, which matters if yours is already on the low side.
Supplements With Weaker Evidence
Several other supplements show blood-pressure-lowering effects in clinical trials, though the evidence is less robust. These include vitamin C, resveratrol (found in red wine extract supplements), cocoa flavonoid supplements, melatonin (particularly the controlled-release form taken at night), isoflavones from soy, probiotics, and lycopene. Individually, their effects tend to be smaller, but they add to the total if you’re taking several.
Coenzyme Q10 (CoQ10) deserves a specific mention because it’s widely marketed for heart health. Despite earlier enthusiasm, a Cochrane review found moderate-quality evidence that CoQ10 does not have a clinically significant effect on blood pressure. If you’re concerned about low blood pressure, CoQ10 is likely not contributing to the problem.
How Stacking Supplements Compounds the Risk
The real danger often isn’t a single supplement but the combination. Someone taking magnesium for sleep, fish oil for heart health, potassium for muscle cramps, and drinking beetroot juice for fitness could easily be shaving 15 to 20 mmHg or more off their systolic pressure without realizing it. Add a daily cup of hibiscus tea and a garlic supplement, and the cumulative effect approaches or exceeds what prescription medications deliver.
This matters most for people already on antihypertensive drugs. The combined effect of prescription medication and multiple blood-pressure-lowering supplements can produce additive drops that cross into true hypotension. Blood pressure below 90/60 mmHg is generally considered low, but symptoms can appear with a relative drop of just 20 mmHg from your baseline, even if the absolute number still looks “normal” on paper.
Signs Your Blood Pressure Is Too Low
Supplement-induced low blood pressure feels the same as any other form of hypotension. The most common symptoms are dizziness or lightheadedness, especially when standing up quickly. You might notice blurred or fading vision, unusual fatigue, trouble concentrating, or an upset stomach. Fainting is possible with larger drops. These symptoms often come on gradually as supplement levels build in your system over days or weeks, making it easy to attribute them to stress, poor sleep, or aging rather than something you’re taking.
If you’re experiencing these symptoms and take any of the supplements listed above, try stopping them one at a time to see if symptoms improve. Most blood-pressure-lowering effects from supplements reverse within days to a couple of weeks after discontinuation, though the timeline varies depending on the supplement and how long you’ve been taking it.