Rasona (Garlic) in Ayurveda: Properties & Everyday Use

What it is

Rasona, also called Lashuna or Lasuna in Ayurvedic literature, is the bulb of Allium sativum L., garlic (Usha Patil et al., IJAAR review of Ayurvedic and modern literature). It is among the most researched medicinal plants in the world: NCCIH notes "a great deal of research has been done on garlic, especially on its effects on levels of cholesterol and related lipids" (NCCIH). Crushing the clove converts alliin to allicin, the sulfur compound behind garlic's pungency and much of its studied bioactivity (NCCIH). Garlic products differ widely: fresh, dried powder, oil, and aged garlic extract (standardized to S-allylcysteine) are chemically distinct, so trial results from one preparation do not automatically transfer to another.

Classical properties

• Taste (rasa): pungent (Katu), bitter (Tikta)
• Qualities (guna): light (Laghu), dry (Ruksha)
• Potency (virya): warming (Ushna)
• After digestion (vipaka): pungent (Katu)
• Doshas: traditionally said to settle Vata and Kapha; may increase Pitta

Traditional use

NCCIH notes that ancient writings from Egypt, Greece and India describe garlic's use for headache, pneumonia, throat conditions and gastrointestinal disorders (NCCIH). In Ayurveda it is called "Maha aushadha" (the great medicine) and features in classical treatment of vata disorders and as a rasayana (rejuvenative), with uses also recorded for digestion, respiratory complaints and cardiac conditions (IJAAR review). These are traditional claims: the trial evidence is assessed separately below.

What research has looked at

Blood pressure

The human evidence is real but modest. A 2015 systematic review and meta-analysis of 7 randomized, placebo-controlled trials in people with hypertension found garlic lowered systolic blood pressure by about 6.7 mmHg and diastolic by about 4.8 mmHg versus placebo. The authors still concluded that more rigorously designed trials with long-term follow-up are warranted before garlic can be recommended to treat hypertension (Xiong et al., Phytomedicine). An earlier meta-analysis of 11 trials found a mean systolic drop of 4.6 mmHg overall and 8.4 mmHg in the hypertensive subgroup (Ried et al., BMC Cardiovascular Disorders, via DOAJ).

A single well-designed dose–response RCT (n=79, 12 weeks) tested aged garlic extract as an adjunct to existing antihypertensive medication in uncontrolled hypertension: one dose level reduced systolic pressure by 11.8 mmHg versus placebo: but the lower and higher doses did not reach significance, so the dose response is not straightforward (Ried et al., European Journal of Clinical Nutrition). Never use it in place of, or alongside, prescribed medicine without your doctor. NCCIH's overall assessment remains cautious: "limited evidence suggests that garlic supplements may reduce blood pressure to a small extent in people who have high blood pressure" (NCCIH).

Cholesterol

NCCIH states garlic supplements "may reduce levels of total cholesterol and low-density lipoprotein (LDL) cholesterol to a small extent in people who have high blood cholesterol levels" (NCCIH). A 2016 meta-analysis of 39 randomized controlled trials (2,300 participants) found reductions of roughly 10% in total and LDL cholesterol when garlic was taken for more than 2 months by people with slightly elevated concentrations (cited in NCCIH's cholesterol evidence digest). The effect is modest compared with cholesterol-lowering drugs, and an NCCIH-funded trial of three garlic preparations found no effect at all (same digest).

Blood sugar

NCCIH notes garlic supplements "may reduce blood sugar to a small extent in people with diabetes" (NCCIH). This is a small, secondary finding: not a basis for managing diabetes.

What the evidence does not support (yet)

NCCIH is explicit on the negatives: "consuming garlic does not seem to reduce the risk of stomach cancer" and it is uncertain whether garlic influences colorectal cancer risk (NCCIH). For the popular cold-season "immune booster" claim, a 2022 review identified only two studies suggesting possible benefit: both small and methodologically weak (NCCIH).

Safety notes

NCCIH's safety summary (updated February 2025): garlic taken orally has been used safely in research studies lasting as long as 7 years. Side effects include breath and body odor, abdominal pain, flatulence and nausea; some people have allergic reactions (NCCIH).

Three warnings deserve emphasis:

• Bleeding risk. "Taking garlic supplements may increase the risk of bleeding." Tell your healthcare providers: especially before surgery or if you take anticoagulants or aspirin (NCCIH).
• Drug interactions. Garlic has been found to interfere with some drugs, including saquinavir, an HIV drug (NCCIH cholesterol digest).
• Topical burns. Some garlic forms used topically are safe, but "fresh raw garlic may not be safe when used topically. It can cause severe skin irritation and chemical burns" (NCCIH).

Garlic "may not be safe for use during pregnancy or while breastfeeding when taken orally in amounts greater than those found in foods" (NCCIH).

FAQs

Does garlic lower blood pressure?

Modestly, in people who already have high blood pressure. A 2015 meta-analysis of 7 placebo-controlled RCTs found systolic drops of about 6.7 mmHg and diastolic drops of about 4.8 mmHg (Xiong et al.); NCCIH calls the evidence "limited" and the effect small (NCCIH). It is an adjunct, not a replacement for prescribed medication.

Does garlic lower cholesterol?

To a small extent, in people with high cholesterol: NCCIH says garlic supplements may reduce total and LDL cholesterol slightly (NCCIH), and a 39-trial meta-analysis found roughly 10% reductions when taken for more than 2 months (NCCIH digest).

How much garlic was used in the blood-pressure trials?

Swastik does not suggest amounts. The right amount depends on the person, the preparation and the product, so check with a qualified Ayurvedic practitioner or your doctor before taking any herb.

Can garlic prevent cancer?

No. NCCIH states that consuming garlic does not seem to reduce stomach cancer risk and that evidence for colorectal cancer is uncertain (NCCIH). There are no clinical trials supporting a cancer-prevention claim.

Is garlic safe before surgery?

Be cautious: garlic supplements may increase bleeding risk, so tell your healthcare providers before any surgery: especially if you also take anticoagulants or aspirin (NCCIH).

Can raw garlic be put on the skin?

No: NCCIH warns that fresh raw garlic applied topically can cause severe skin irritation and chemical burns (NCCIH).

Sources

• NCCIH — "Garlic: Usefulness and Safety" (updated February 2025): NCCIH
• NCCIH — "High Cholesterol and Natural Products: What the Science Says": NCCIH
• Xiong X et al. "Garlic for hypertension: A systematic review and meta-analysis of randomized controlled trials." Phytomedicine. 2015;22(3):352–361. PMID: 25837272 — PubMed · PMID 25837272
• Ried K, Frank OR, Stocks NP. "Aged garlic extract reduces blood pressure in hypertensives: a dose-response trial." European Journal of Clinical Nutrition. 2013;67(1):64–70. PMCID: PMC3561616 — PubMed · PMID 23169470
• Ried K et al. "Effect of garlic on blood pressure: A systematic review and meta-analysis." BMC Cardiovascular Disorders — doaj.org
• Usha Patil et al. "Rasona (Allium sativum): A Wonder Drug from Ancient to Modern and Kitchen to Medicine." International Journal of Ayurveda and Allied Sciences (IJAAR) — ijaar.in

Disclaimer

This article is for educational purposes only and is not medical advice. Herbal products can interact with medications and are not suitable for everyone. Talk to a qualified healthcare practitioner before use — especially if you are pregnant, breastfeeding, managing a medical condition, or taking prescription medicines.