Whenever I talk to someone about switching to a natural deodorant, I hear the same worry: "What if I react to it?" It's a fair question. Your underarms are one of the most sensitive, most shaved, most rubbed-against patches of skin on your body. So before you swap your whole routine, there's one small step that is worth the effort: a patch test.
It takes about two minutes of effort and a day of waiting. Here's how to do it, and why I always recommend it, including for our own deodorant.
What is a patch test?
A patch test is simply trying a product on a small area of skin first, before using it properly. If your skin is going to react, you'd much rather find out on a patch the size of a 20 cent piece than across both underarms the morning of a big day.
It's not a guarantee. Nothing is, and I'd be wary of anyone who tells you otherwise. But it is a sensible, low-effort way to catch an obvious reaction early.
Why it matters more for sensitive skin
Si:zen began with a deodorant for sensitive skin, so this one is close to my heart. If your skin has reacted to products before, or you've had a rash from another natural deodorant, you already know how uncomfortable underarm irritation can be. It's also the reason we left bicarbonate of soda out of our formula, because it can irritate the underarm for some people. We use magnesium hydroxide instead.
But "formulated for sensitive skin" is not the same as "guaranteed to suit every single person". Everyone's skin is different, and we always recommend patch testing first. Our formula uses a small set of ingredients on purpose, which makes it easier to understand what you're putting on your body, and easier to work out what's behind a reaction if one ever happens.
If you're switching from an antiperspirant, a patch test is especially useful. Your underarms are already adjusting to life without aluminium, and you want to be able to tell the difference between your skin settling in and your skin disliking something.
How to patch test, step by step
1. Start with clean, dry skin. Choose a day when you haven't just shaved or waxed. Freshly shaved skin is more reactive, and it can make the result harder to read.
2. Pick your spot. The inner forearm or inner elbow works well because the skin is thin and easy to keep an eye on. Some people prefer to test a small area of the underarm itself, which is a good option too, as long as it's a small patch.
3. Apply a small amount. One light swipe over an area about the size of a 20 cent piece is plenty. More product won't tell you anything extra.
4. Leave it alone. Let it absorb and try not to wash or rub the area. Then wait a full 24 hours before judging the result.
5. Check in. Look at the spot after a few hours and again at the 24 hour mark. You're watching for redness, itching, burning, bumps or swelling beyond the patch.
6. Decide. If your skin looks and feels normal, you can start using the product as directed. If you notice a reaction, wash the area gently with water, stop using the product, and don't push through. If the reaction is strong or doesn't settle, check in with your pharmacist or doctor.
Irritation or transition period? How to tell the difference
This is the bit that trips most people up. When you move away from an antiperspirant, it's common to notice a bit more sweat and a bit more odour for the first one to two weeks while your underarms rebalance. That's the transition period, and it's normal. I've written about it in detail in Why Does Natural Deodorant Take Time to Work?
The transition period is about smell and sweat. A patch test reaction is about how your skin looks and feels. Extra odour while your body adjusts is not a sign you should stop. Redness, itching, burning or a rash is your skin telling you something different, and that deserves attention.
A note on fragrance
Our deodorant contains a skin-safe fragrance for the Santal scent. If you know you're sensitive to fragrance, the patch test is particularly worthwhile, and it's worth checking the full ingredient list before you buy. We're also working on a fragrance-free option. If you ever have questions or experience a reaction, please email us at hello@sizen.com.au. I'd genuinely like to hear about it.
A few extra tips
Test one new product at a time, so you know what's responsible if something happens. Skip the patch test if your skin is already irritated, and wait until it has settled. And when you do start using it, apply one or two light swipes to clean, dry underarms. You don't need to layer it on.
Every si:zen, a little care
Life moves in seasons, and so does your skin. A two-minute patch test is a small, kind thing to do for your body before you change a daily habit. Natural living should feel easier and calmer, not like a gamble. If you'd like to try our aluminium-free deodorant, you can find it here.
Amy x