Onion benefits for the body: raw, cooked and skin uses

Updated on 21 September 2026Published on 25 August 2018

Onion is the cheapest herbal ally in the house: one bulb, a board and a knife. This page sets out what onion actually contains, what herbalists and country tradition have long done with it — raw, cooked, as a honey macerate or laid on the skin — and the few situations where you should go easy on it.

Onion at a glance
Item	Detail
Botanical name	Allium cepa
Family	Amaryllidaceae (long classed with the Liliaceae, the lily family)
Part used	The bulb, mainly; also the green tops of spring onions
Forms of use	Raw, cooked, honey or sugar macerate, poultice, juice
Harvest season	Midsummer to late summer, once the leaves flop and yellow
Taste	Sharp, pungent and sulphurous raw; sweet, mellow and almost jammy cooked

What it is credited with

Onion has a long reputation as a diuretic food — raw, it is the form tradition favours for that.
Herbalism credits it with stimulating and antibacterial qualities, which is why it turns up in so many old household remedies.
Its polyphenol, selenium and copper content gives it a standing as an antioxidant food, traditionally eaten to support the body against everyday wear and tear.
In traditional herbalism, cooked onion — softening and emollient — was used to ease a stubborn, rattling cough and to loosen thick winter phlegm.
Cooked onion is traditionally eaten to rouse the appetite and support digestion, and country kitchens used it against sluggish bowels and trapped wind.
Folk practice laid a slice of raw onion on insect bites, itchy spots and small inflamed blemishes on intact skin.
Onion juice has a long cosmetic reputation for skin and hair, used in home rinses and masks.
Naturopathy treats it as a "cleansing" vegetable to include regularly in an ordinary balanced diet, rather than as a one-off cure.

How to use it

Raw, in the day’s food

Half a small onion, finely sliced, is plenty for a salad or a sandwich for two.
Soak sliced raw onion in cold water for 10 minutes to tame the bite without losing the crunch.
Red onion is the mildest raw; yellow is the sharpest; white sits between the two.
Add it at the last moment, dressed with oil and lemon or vinegar.

Cooked, the gentlest form

Two or three onions sliced and sweated slowly in oil or butter for 20 to 30 minutes turn sweet and easy on the stomach.
Onion soup, baked whole onions, stuffed onions, pies, fried rings, mash: all count.
Traditionally taken as a warm bowl in the evening through the cold months.
It seasons meat and fish, sits well with nearly every vegetable, and is the base of countless sauces and pâtés.

The old honey macerate

Slice one onion into a bowl, cover with runny honey or unrefined sugar, cover and leave overnight at room temperature.
By morning a thin syrup has drawn out. Strain it off and keep it in a jar in the fridge for two to three days.
Tradition takes a spoonful two or three times a day for a few days during a scratchy, coughing patch — no longer.
Taste: sweet, sharp, faintly savoury. Lemon juice makes it easier to swallow.

On the skin

Cut a thick slice of raw onion and hold it on the bite or itchy patch for a few minutes.
Use it on unbroken skin only, and rinse afterwards.
Test on the inside of the forearm first: onion juice stings sensitive skin.

cooking onion benefits — *Slow cooking turns the sharp bulb sweet and easy to digest*

Forms of use compared
Form	How it is prepared	What tradition uses it for
Raw	Thinly sliced, in salads, sandwiches or salsas	The form credited with diuretic and stimulating action
Cooked	Sweated, baked, stuffed or simmered in soup, 20–30 minutes	Traditionally eaten to support appetite and digestion, and to ease a stubborn cough
Honey macerate	Sliced onion covered in honey, left overnight, strained	The classic household syrup for a scratchy winter throat and cough
Poultice or slice	A thick raw slice held on intact skin for a few minutes	Folk use on insect bites, itching and small inflamed spots

onion nutritional content — *Each ring of the sliced bulb is one leaf the plant grew*

Cautions

Raw onion is not always well digested by people with a delicate or easily irritated digestive tract. Cooked onion is far gentler.
It can aggravate reflux, heartburn and bloating in sensitive people, and is high in fermentable sugars — a known trigger on a low-FODMAP regime.
Allergy to onion, garlic and other alliums exists, though it is uncommon. Stop at the first sign of a reaction.
Pregnancy and breastfeeding: onion as food is part of normal eating. Concentrated preparations — syrups, juices, cures taken daily — are best discussed with a midwife or doctor first.
Children: cooked onion in food is fine. Never give honey-based preparations to a baby under one year old.
On medication: if you take anticoagulants or blood-thinning drugs, or medication for blood sugar, keep your onion intake steady and mention any concentrated onion cure to your doctor or pharmacist.
Apply raw onion to unbroken skin only, for a few minutes, and never on open wounds, burns or the eye area.
Onion is toxic to dogs and cats — do not share trimmings or leftovers with pets.
Growing note: as for the soil type, avoid clay-laden soil and prefer it light, soft and well drained. Onion does not tolerate acid soil; a siliceous-clay mix suits it best.
Onion is food and a traditional household remedy, not a treatment. Persistent symptoms belong with a healthcare professional.

Frequently Asked Questions

The one thing to remember: eat it cooked most days for gentleness, raw now and then for its diuretic reputation — and keep the honey macerate for a scratchy winter week, not as a daily habit.

Is raw or cooked onion better?

They are used differently. Raw onion is the form tradition credits with diuretic and stimulating qualities, while cooked onion is the soft, sweet version herbalism turns to for appetite, digestion and a stubborn cough. If raw onion sits badly with you, cook it and lose nothing in flavour.

How do I make the old onion and honey syrup?

Slice one onion into a bowl, cover it with runny honey, cover the bowl and leave it overnight at room temperature. Strain off the thin syrup in the morning and keep it refrigerated for two or three days. Tradition takes a spoonful two or three times a day during a coughing patch, and never gives it to a baby under one year old.

Does it matter which colour of onion I use?

Each variety differs a little in flavour and in what it brings nutritionally, so the sensible move is to rotate them rather than hunt for one superior type. Red is mildest raw, yellow the sharpest, white in between. Mixing them across the week is the simplest approach.

How long do onions keep?

Fresh bunched onions last about a week in the vegetable drawer of the fridge. Dried, properly cured bulbs keep for months in a dark, dry, well-ventilated spot, and the darkness is what stops them sprouting. Discard any that turn soft or smell sour.

Can I use onion on my skin?

Folk practice lays a thick raw slice on insect bites, itching or a small inflamed blemish for a few minutes, then rinses. Use it on intact skin only, never on open wounds or near the eyes, and test on the inside of your forearm first because the juice stings sensitive skin.

This information is provided for general interest and reflects the traditional use of plants. It is not a substitute for medical advice. If you are on medication, pregnant, or in any doubt, ask a healthcare professional.

Written by Gaspard Lorthiois | Loves helping out, especially when it comes to growing things. Worked in herbal medicine, runs a farm, and dabbles in tech. Master's degree and engineer.

La page de Gaspard Lorthiois