Blood Pressure and Garlic
Garlic is said to lower high blood pressure - or so we read time and again. Should people with high blood pressure really consume this pungent bulb, or the powders and granules made from it, more often?
In 2008, eleven different studies on lowering blood pressure with garlic were analyzed. Some studies did show greater reductions in blood pressure with garlic compared with placebos (the higher the starting blood pressure, the greater the possible reduction in blood pressure), but no consistent results were found. This was partly due to the insufficient methodological quality of the studies. For example, information on how blood pressure was measured during the observation period of each study was lacking.
In 2010, Australian researchers examined the effect of so-called black garlic in patients with hard-to-control high blood pressure. Black garlic is regular garlic that's been "aged" by fermentation. The 50 participants took four capsules daily for twelve weeks containing black garlic extract (960 mg with 2.4 mg S-allylcysteine) or a matching placebo. The results showed a reduction in blood pressure, but it was not statistically significant.
A 2016 meta-analysis also showed a reduction in blood pressure values, but about one third of the study participants did not respond to garlic.
In 2019 another meta-analysis was published that looked at 12 studies in which participants took garlic as a powder or capsule, or in the form of aged garlic.
This analysis found that garlic lowered participants' systolic blood pressure by an average of 8 – 10 mmHg and diastolic pressure by about 5-6 mmHg. However, this did not occur in all participants; some experienced smaller reductions than these averages, meaning their blood pressure dropped less. This is attributed to the fact that the response to the garlic preparation apparently depends on how well each participant is supplied with B vitamins.
It was also shown that aged garlic has a positive effect on the arteries, specifically on arterial stiffness. It was further found that aged garlic, like other garlic products, has a blood-thinning effect, but does not increase the risk of bleeding.
In 2019 another meta-analysis was published that looked at 12 studies in which participants took garlic as a powder or capsule, or in the form of aged garlic.
This analysis found that garlic lowered participants' systolic blood pressure by an average of 8 – 10 mmHg and diastolic pressure by about 5-6 mmHg. However, this did not occur in all participants; some experienced smaller reductions than these averages, meaning their blood pressure dropped less. This is attributed to the fact that the response to the garlic preparation apparently depends on how well each participant is supplied with B vitamins.
It was also shown that aged garlic has a positive effect on the arteries, specifically on arterial stiffness. It was further found that aged garlic, like other garlic products, has a blood-thinning effect, but does not increase the risk of bleeding.
It's important to mention that garlic can interact with various medications. It can enhance the antiplatelet ("blood-thinning") effect of platelet aggregation inhibitors, such as aspirin. Because an increased bleeding tendency may also occur when taken with oral anticoagulants like Marcumar, and with newer agents such as Xarelto, Eliquis, etc., garlic supplements are not recommended in these situations. On the other hand, garlic can reduce the effectiveness of protease inhibitors in people with HIV.
The 2019 meta-analysis confirmed a blood-pressure-lowering effect of garlic. However, this was not seen in all participants. Some people respond to garlic with lower blood pressure, while others unfortunately do not. As that meta-analysis suggested, this may also depend on B-vitamin status. Considering the possible interactions mentioned, you can enjoy fresh garlic as a food. Whether to use a garlic supplement to lower blood pressure should, however, be discussed with your treating doctor first, especially if you are already taking medication for high blood pressure.
Sources:
- https://www.thieme-connect.com/products/ejournals/abstract/10.1055/a-0659-7629
- https://www.aerzteblatt.de/blog/43556/Knoblauch-Dufte-fuer-den-Blutdruck
- https://www.maturitas.org/article/S0378-5122%2810%2900227-6/abstract
- https://www.ncbi.nlm.nih.gov/pubmed/22895963
- https://www.aerzteblatt.de/nachrichten/73371/Pflanzliche-Praeparate-Diese-Wechselwirkungen-sollten-Kardiologen-kennen
- https://www.jacc.org/doi/10.1016/j.jacc.2016.11.078
- https://pubmed.ncbi.nlm.nih.gov/32010325/
- https://www.spandidos-publications.com/10.3892/etm.2019.8374
This article is from Tensana – the leading app since 2011, helping hundreds of thousands of people monitor their blood pressure every day.
Our content is based on carefully researched, evidence-based data and is continuously updated (as of 12/2025).
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
