Palandu (Onion) in Ayurveda: Properties & Everyday Use

What it is

Palandu is the Sanskrit name for the onion: the bulb of Allium cepa L. (family Amaryllidaceae, formerly placed in Liliaceae), one of the world's oldest cultivated vegetables and a medicine-food used across Ayurveda, Unani, and folk traditions. The WHO monograph Bulbus Allii Cepae defines the herbal drug as the fresh or dried bulb, with organosulfur compounds (thiosulfinates, cepaenes) and the flavonol quercetin among the constituents of pharmacological interest (WHO Monographs on Selected Medicinal Plants, Vol. 1, 1999). White and red varieties are both used; Ayurvedic texts distinguish rakta palandu (red) and shweta palandu (white) forms.

Classical properties

• Taste (rasa): sweet (Madhura), pungent (Katu)
• Qualities (guna): heavy (Guru), oily (Snigdha)
• Potency (virya): warming (Ushna)
• After digestion (vipaka): sweet (Madhura)
• Doshas: traditionally said to settle Vata; may increase Pitta and Kapha

Traditional use

The WHO monograph organizes onion's uses into three tiers: uses supported by clinical data (principally prevention of age-dependent changes in blood vessels, and loss of appetite). Uses described in pharmacopoeias and traditional systems (treatment of bacterial infections such as dysentery, use as a diuretic, treatment of ulcers, wounds, scars and keloids, asthma, and as an adjuvant in diabetes); and folk uses not supported by experimental or clinical data (WHO Monographs, Vol. 1). In Ayurvedic practice, palandu juice is traditionally instilled in the nostrils for nosebleeds, warmed juice is put in the ear for earache, and heated onion poultices are applied for joint pain and swelling: these are traditional applications, not clinical proof (Seema et al., World J Pharm Res 2017).

What research has looked at

Blood pressure (randomized trial of quercetin from onion skin)

In a randomized, double-blind, placebo-controlled crossover trial (n=70 overweight-to-obese adults with pre-hypertension or stage 1 hypertension), quercetin from onion skin extract taken for 6 weeks reduced 24-hour ambulatory systolic blood pressure by 3.6 mmHg versus placebo in the hypertensive subgroup, with no significant effect in pre-hypertensives and no changes in cholesterol, glucose, or oxidative markers (Egert et al., Br J Nutr 2015). This tested a quercetin extract, not whole onion: and the effect was modest and limited to people already hypertensive.

Acute vascular effects (randomized crossover trial)

In a randomized, double-blind, placebo-controlled crossover meal study (n=22 overweight-to-obese hypertensive patients), a single dose of quercetin from onion skin extract did not change postprandial blood pressure or endothelial function after a high-fat, high-carbohydrate meal (Brüll et al., Eur J Nutr 2016). A single dose does nothing measurable: any effect would require sustained intake.

Immune markers (randomized trial)

An 8-week randomized, double-blind, placebo-controlled trial of onion peel extract found no significant effect on natural killer cell activity or serum cytokines (IL-2, IL-6, IL-12, IL-1β, IFN-γ, TNF-α) in adults (Cho et al. 2024). Onion's popular "immune booster" reputation is not supported by this trial.

Safety notes

Allergic reactions such as rhinoconjunctivitis and contact dermatitis have been reported with onion (WHO Monographs, Vol. 1). The WHO monograph reports no general precautions concerning drug interactions, pregnancy, nursing mothers, or pediatric use: which means none were documented, not that safety is proven. As a widely eaten food, onion is generally safe in culinary amounts; concentrated extracts have only short-trial data. People on anticoagulant or antiplatelet drugs should note that onion constituents have shown antiplatelet activity in laboratory and animal studies, so medicinal-strength use deserves a clinician's input.

FAQs

Is palandu just the onion in my kitchen?

Yes: palandu is the Sanskrit name for onion (Allium cepa), and Ayurvedic texts distinguish red (rakta) and white (shweta) varieties (Seema et al., World J Pharm Res 2017). Traditional medicinal uses (juice for nosebleeds, earache, poultices) use the same plant, but in preparations and amounts beyond normal cooking.

Does onion lower blood pressure?

Weakly, at best. One 6-week-per-period crossover RCT found a 3.6 mmHg systolic reduction in already-hypertensive people using quercetin extracted from onion skin, not whole onion, while a single-dose study found no effect at all (Egert et al. 2015; Brüll et al. 2016). Eat onions as a healthy food, not as a blood-pressure treatment.

What does WHO actually endorse onion for?

Prevention of age-dependent changes in blood vessels and loss of appetite are the uses WHO lists as supported by clinical data. Dysentery, diuretic use, wounds, asthma, and diabetes-adjuvant use are listed as traditional/pharmacopoeial, and many folk uses (aphrodisiac, earache, fevers) as unsupported by experimental or clinical data (WHO Monographs, Vol. 1).

How much onion did the studies use?

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.

Is onion safe in pregnancy?

Onion as food is a normal part of diets worldwide. The WHO monograph documents no specific precautions for pregnancy or nursing: which reflects absence of reported data rather than proven safety of medicinal-strength preparations (WHO Monographs, Vol. 1). Culinary use is uncontroversial; medicinal doses should be discussed with a clinician.

Sources

• World Health Organization. WHO Monographs on Selected Medicinal Plants, Vol. 1 (1999) — Bulbus Allii Cepae — ogwlresources.s3.amazonaws.com
• Egert S et al. "Effects of a quercetin-rich onion skin extract on 24 h ambulatory blood pressure and endothelial function in overweight-to-obese patients with (pre-)hypertension: a randomised double-blinded placebo-controlled cross-over trial." Br J Nutr. 2015 — core-varnish-new.prod.aop.cambridge.org
• Brüll V et al. "Acute intake of quercetin from onion skin extract does not influence postprandial blood pressure and endothelial function in overweight-to-obese adults with hypertension: a randomized, double-blind, placebo-controlled, crossover trial." Eur J Nutr. 2016 — springermedizin.de
• Cho HJ et al. "Effect of onion (Allium cepa L.) peel extract on natural killer cell and cytokines in a randomized, double-blind, placebo-controlled trial." Nutr Res Pract. 2024 — PMC · PMC10861340
• Seema et al. "Palandu (Allium cepa): therapeutic uses." World J Pharm Res. 2017;6(2) — wisdomlib.org

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.