Onion juice is simply the liquid squeezed from raw onions. You can make it with a blender, a grater or a food processor and a strainer: no juicer needed. It is mainly used as a cooking ingredient and as a traditional hair treatment. This guide shows three easy methods, how to store it safely and what the research says about using it on hair.
Quick answer: Peel and roughly chop 1 medium onion, blend it with 1–2 tablespoons of water for 30 seconds, then strain through a fine-mesh strainer or cheesecloth and squeeze. One medium onion gives about ¼ cup (60 ml) of juice. Store it in a sealed jar in the fridge for up to 3 days.
What You Need
- 1–2 medium onions (red, yellow or white all work; red is slightly milder)
- 1–2 tablespoons water (only for the blender method)
- A blender, food processor or box grater
- A fine-mesh strainer, cheesecloth or nut-milk bag
- A clean glass jar with a lid
How to Make Onion Juice: 3 Methods
Method 1: Blender (fastest)
- Peel the onion, cut off the root end and chop it into quarters.
- Blend with 1–2 tablespoons of water for about 30 seconds until it is a smooth pulp.
- Pour the pulp into a strainer lined with cheesecloth set over a bowl.
- Gather the cloth and squeeze firmly until no more juice comes out.
Method 2: Grater (no machine)
- Grate the peeled onion on the fine side of a box grater into a bowl.
- Spoon the grated onion into cheesecloth and squeeze the juice into a bowl.
- This gives slightly less juice than a blender but needs no water.
Method 3: Juicer
A masticating (slow) juicer extracts onion juice without water and gives the cleanest result. Wash the juicer straight away, because onion smell lingers in plastic parts. See how to wash a juicer.
Tips to Reduce the Smell and Tears
- Chill the onion in the fridge for 30 minutes before cutting; cold onions release fewer eye-irritating compounds. More ideas in how to cut an onion without crying.
- Work quickly and keep the juice covered.
- Wash your hands, board and blender with cold water first, then soap; rubbing your hands on stainless steel also helps.
How to Store Onion Juice
Raw onion juice spoils quickly. Keep it in a clean, airtight glass jar in the fridge and use it within 3 days. Freeze extra in an ice-cube tray for up to 3 months and thaw only what you need. Throw it out if it smells sour or looks cloudy and fizzy. Our juice storage guide explains why fresh juices go off quickly.
Using Onion Juice on Hair: What the Research Shows
The most cited study is small: in 2002, researchers in Iraq asked 23 people with patchy hair loss (alopecia areata) to apply crude onion juice twice daily. After 6 weeks, hair regrowth was reported in most of them, compared with far fewer in a tap-water group (Sharquie & Al-Obaidi, Journal of Dermatology, 2002). The study was small and not blinded, and it did not test common genetic hair thinning, so onion juice is not a proven hair-growth treatment.
- How people use it: massage 1–2 tablespoons into the scalp, leave it on for 15–30 minutes, then shampoo.
- Patch test first: onion juice can irritate skin. Test it on a small area of the inner arm for 24 hours.
- See a dermatologist for sudden or patchy hair loss; it can have medical causes that need treatment.
Drinking Onion Juice
Plain onion juice is very strong and can cause heartburn, gas and bad breath. Most people use it in small amounts in marinades, dressings and soups. If you want to drink onion, blend it with fruit instead, as in our onion and banana juice, or try onion water. For what onions contain and the health research, see benefits of onion juice.
Frequently Asked Questions
How much juice do you get from one onion?
A medium onion (about 150 g) gives roughly 3–4 tablespoons (45–60 ml) of juice, depending on the method and how hard you squeeze.
Which onion is best for juice?
Any onion works. Red onions are milder, while yellow and white onions are stronger. For hair use, most people use red or yellow onions.
Can I make onion juice without a blender or juicer?
Yes. Grate the onion finely and squeeze it through cheesecloth or a clean thin towel.
How long does onion juice last?
Up to 3 days in a sealed jar in the fridge, or about 3 months frozen in ice-cube trays.
