Henna & Indigo Patch Test: Why It Matters & How to Do It Right

~ By Deepali Razdan

Switching to plant-based hair colour is one of the kindest things you can do for your scalp and hair — but before you dive in, there's one important step that takes just 48 hours and could save you a lot of discomfort: the patch test.

Whether you're new to henna and indigo or switching from a chemical dye, this guide walks you through exactly how to patch test an SVA colour kit — and what to look for.

Why Do a Patch Test?

Natural does not mean allergy-free! Even plant-based ingredients can occasionally cause a reaction in sensitive individuals. Just like one can be allergic to nuts & seeds, some can be allergic to henna or indigo leaf powders. Even though SVA formulas are pure botanicals — they can trigger a response in people with specific sensitivities.

A patch test lets you check how your skin reacts to the product before applying it all over your scalp. It's a small step that gives you confidence going into your first full colour session.

It's especially important if you:

Have a sensitive or itchy scalp.
Have a history of skin allergies, eczema, psoriasis, or dermatitis.
Are sensitive to any natural ingredients.
Have never used henna or indigo before.
Have used henna or indigo before and had a reaction.
Are switching from a PPD-based chemical hair dye.
Have an underlying medical issue.
Have an autoimmune condition.

What You'll Need for a Patch Test

SVA offers a free patch test kit — just reach out to our customer care team and we'll send it across to you (a nominal delivery charge applies).

SVA Patch test kit (sample of henna and indigo powders).
Warm water (ideally distilled or filtered).
2 small bowls and spoons.
A cotton bud or clean fingertip.
Clingwrap to cover.

SVA patch test kit ingredients: henna powder, indigo powder, bowls, spoons, clingwrap roll and warm water

Step-by-Step: How to Patch Test SVA Hair Colour

Step 1: Mix a Small Amount of Both Powders for Testing

In a small bowl, combine about 1 teaspoon of your SVA henna powder with 2 teaspoons of hot water to make a thick paste.
In a separate bowl, combine 1 teaspoon of SVA indigo powder with 2 teaspoons of warm water to make a thick paste.
Keep the paste consistency of toothpaste or yogurt. You don't need much — you're only applying a pea-sized amount to your skin.

Step 2: Choose Your Test Area

Apply the paste to a small area of skin that's easy to monitor but not too exposed. Good spots include:

The inner bend of your elbow
Behind one ear
The inner wrist (preferable)

These areas have thinner, more reactive skin — which makes them ideal for testing.

Diagram showing recommended patch test areas on the body: inner elbow, behind ear, and inner wrist

Step 3: Apply and Cover

Use a cotton bud or your fingertip to apply a small dot of each paste on the inner side of each wrist — about the size of a pea or a 50-cent coin will do.

Cover the paste with clingwrap and leave it on for 2–3 hours. Then rinse off gently with warm water and soap.

Applying henna and indigo paste to inner wrist for patch testing

Patch Test Wrists - Clingwrap Wrapped Around

Step 4: Wait 48 Hours

This is the most important part. After rinsing, monitor the area over the next 48 hours. You're looking out for:

Redness or inflammation
Itching, burning, or tingling
Swelling, raised skin, or hives
Any unusual skin reaction
Nausea or headache

Some temporary staining of the skin is completely normal — henna is a natural dye, and it will fade within a few days. Some may notice a bluish stain with indigo as well, which also fades. Staining is normal. Redness is not.

Skin showing normal henna stain after patch test — orange-brown colour that fades naturally

Step 5: Evaluate and Proceed

If you experience no irritation after 48 hours, you're good to go. You can proceed with your full colour application with confidence.

If you notice any discomfort or reaction, do not proceed with the full application. Rinse the area thoroughly and consult a dermatologist if symptoms persist.

Clear patch test result showing no irritation — skin looks calm and normal after 48 hours

A Note on Indigo

Some people who are fine with henna may have a sensitivity specifically to indigo. Testing them separately gives you a complete picture. If you feel any sensitivity with indigo, please connect with the SVA Customer Care team to discuss options. We can do further testing to see if you can tolerate our diluted indigo proportions used with Plant Toner.

How Often Should You Patch Test?

If you've been using SVA colour regularly without any issues, you don't need to patch test before every application. However, it's worth repeating a patch test if:

You've had a gap of 12+ months since your last use.
You've recently developed new allergies or skin sensitivities.
You're trying a new SVA formula for the first time.
You've had any illness that may have affected your immune response.

Ready to Colour?

Plant-based colour is a journey — and starting safely is the best first step. Once your patch test is clear, you're all set for a full, confident colour session.

Want to see the full application process before you begin? Watch our step-by-step tutorial on Instagram:

▶ Watch Application Tutorial on Instagram

Shop SVA Hair Colour

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Deepali Razdan

Deepali Razdan is a certified organic cosmetic formulator from Formula Botanica (UK) and the founder of SVA Plant Based Hair Dyes. For over a decade, she has researched the science and artistry of plant-based hair dyes, with a special focus on henna and indigo. Having helped more than 1,000+ women across Singapore transition to natural grey coverage, Deepali is passionate about creating chemical-free hair colour solutions that are effective, elegant and rooted in plant science.