🧅 What Is Fermented Onion Juice?

By TheFoodieDad Last updated Jul 14, 2025

Fermented onion juice is made by lacto-fermenting onions in salt water (brine) or their own juices. This process grows beneficial bacteria (probiotics) that enhance digestion, immunity, and nutrient absorption. The result is a tangy, mildly sour juice rich in enzymes and gut-friendly microbes.

✅ Benefits
❌ Drawbacks

Benefits of Fermented Onion Juice

✅ Internal (Drinking)

Probiotic Support

Helps restore gut flora, supports digestion, and boosts immunity
Anti-inflammatory & Antioxidant

Fermentation enhances bioavailability of compounds like quercetin and allicin
Detoxifying

Helps cleanse the liver and supports metabolic functions
Better Tolerance

Gentler on the stomach than raw onion juice — lower chance of gas or irritation

✅ External (Topical)

All the same hair and skin benefits as raw onion juice — but with added:

Enzymes that may help exfoliate the skin
Balanced pH – better for sensitive skin or scalp

Risks and Drawbacks of Fermented Onion Juice

Possible Digestive Discomfort
- Although fermentation reduces harshness, fermented onion juice can still cause gas, bloating, or stomach upset in some people, especially if consumed in large amounts or if they have sensitive digestion
Allergic Reactions or Skin Irritation
- When applied externally, fermented onion juice may cause irritation, redness, or allergic reactions, particularly for sensitive skin or scalp
- Always do a patch test before topical use
Risk of Contamination
- Improper fermentation can lead to growth of harmful bacteria or mold. Signs include foul odor, discoloration, or visible mold. Such batches should be discarded immediately
Strong Smell and Taste
- Fermented onion juice has a strong, tangy smell and flavor that some people find unpleasant or overpowering, which may limit its use
Interactions with Medications
- Like raw onion juice, fermented onion juice may have blood-thinning effects and could interact with blood-thinning or other medications. Consult a healthcare provider if you have concerns
Not Suitable for Everyone
- People with certain health conditions, pregnant or breastfeeding women, or young children should exercise caution and consult a doctor before regular internal use

🧃 How to Make Fermented Onion Juice

Making fermented onion juice at home is surprisingly easy and requires just a few basic ingredients.

✳️ Ingredients you’ll need:

1–2 onions (red or yellow)
1 teaspoon non-iodized salt (like sea salt or Himalayan)
1 cup filtered water (or let tap water sit out 24 hours to dechlorinate)
Optional: garlic, ginger, peppercorns for flavor or added benefits

🥣 Step-by-step guide to making fermented onion juice:

Chop onions into thin slices or small chunks
Place them in a clean glass jar (leave 1 inch of headspace)
Dissolve salt in water, then pour over onions to fully submerge
Use a clean weight (like a glass pebble or leaf of cabbage) to keep onions submerged
Cover loosely with a lid or cloth (for gases to escape)
Ferment at room temperature (18–22°C / 64–72°F) for 3–7 days
Taste daily. When tangy and mildly sour, strain the brine and store in the fridge

🧪 Optional: After fermenting, you can blend and strain to make a more potent “fermented onion juice” extract.

Internal (Drinking it)

Start with 1–2 teaspoons daily, either:
- On an empty stomach, or
- Before meals to aid digestion
Can be diluted in warm water or added to salad dressings or soups (after cooking)

⚠️ Avoid heating, or you’ll kill the probiotics.

External (Hair/Scalp/Skin)

Apply the liquid directly to the scalp, acne spots, or dark patches
Leave on for 15–30 minutes, then rinse with warm water
Use 2–3 times a week

⚠️ Still do a patch test before first use, especially if you have sensitive skin.

🤼 Raw Fermented Onion Juice VS Fermented Onion Juice

Feature	Raw Onion Juice	Fermented Onion Juice
Smell	Strong	Milder, tangy
Stomach Tolerance	Can be harsh	Gentler
Probiotics	❌	✅ Yes
Skin Use	Good	Excellent (pH-balanced)
Hair Use	Stimulating	Gentler, nourishing
Shelf Life	3–4 days (fridge)	1–2 weeks (fridge)

💡 Tips, precautions, and storage

Store fermented juice in a sealed glass container in the fridge
If it smells rotten, foams excessively, or has mold — discard it
You can also reuse the brine to ferment a new batch (like a “starter”)