How to Patch Test a New Oil or Powder
To patch test a new oil, blend or powder, apply a small amount to the inner forearm or behind the ear, leave it and wait 24 hours (48 hours for henna). If there is no redness, itching, swelling or burning, you can go ahead. If there is, wash the area with mild soap and water and do not use the product.
Why patch test?
Any ingredient, plant-based or not, can disagree with someone's skin. As the U.S. Food and Drug Administration explains in its guidance on allergens in cosmetics, reading labels and testing are simple ways to avoid a reaction. A patch test takes a minute to set up and spares you a reaction across your whole face or scalp.
How to patch test, step by step
- Choose the spot: the inner forearm or the skin just behind the ear. Both are delicate and easy to watch.
- Clean it: wash with mild soap and water, then pat dry.
- Apply a small amount: about the size of a coin, used exactly as you plan to use the product.
- Leave it: do not wash the area, and avoid covering it with tight clothing.
- Wait 24 hours, checking a few times.
- Read the result. No reaction? Go ahead. Any reaction? Wash it off and do not use it.
What to test, and how
| Product | What to test | Wait |
|---|---|---|
| Pure carrier oils | A few drops of the oil | 24 hours |
| Essential oils | The diluted blend, never the neat oil | 24 hours |
| Neem | The 1:9 blend | 24 hours |
| Leaf and peel powders | A little paste, mixed as you will use it, rinsed off after the usual time | 24 hours |
| Henna | A small amount of paste, plus a strand test on hair | 48 hours, before every application |
For essential oils, mix the blend first: see Essential Oils and Carrier Oils. For neem, see How to Use Neem Oil for Hair. For henna, see our pure henna guide.
Signs to watch for
- Redness or a rash
- Itching or burning
- Swelling, bumps or blisters
Mild warmth from an essential oil blend that fades within minutes is common; anything that lasts, spreads or worsens is a reaction. If you notice swelling of the face, lips or eyes, or difficulty breathing, seek medical help straight away.
The strand test, for hair
Hair has its own test. Before using henna, Mashat, or an oil on colored or recently bleached hair, apply the product to a small, discreet strand, usually from underneath at the nape, and rinse as normal. Check the color and feel once dry. Henna's final color takes 48 hours to settle.
What a patch test can and cannot tell you
A clear patch test is reassuring, but not a guarantee: skin can react to a product later, or on a more sensitive area such as the face. Introduce one new product at a time, so that if something does not suit you, you know which one. Stop using any product if irritation occurs.
Read the label first
Before you even test, check the ingredients for anything you know you react to. At FAYNAN, for example, the Botanical Hair Ritual Oil contains sesame and wild pistachio (a tree nut), and Pure Wheat Germ Oil is not for anyone with a wheat or gluten allergy. Every product page lists full ingredients and cautions.
Who should take extra care
- Anyone with sensitive skin or known allergies.
- Children: essential oils and neem are not for use on children.
- If you are pregnant, breastfeeding or under medical care, ask a healthcare professional before using essential oils.
New to oils? Start with How to Choose a Hair Oil or How to Choose a Face Oil, and browse the Pure Botanicals collection.