When it comes to deodorants, it is easy to mistake a chemical burn for an allergic reaction and vice versa. 

A chemical burn happens when the pH of your deodorant is higher or lower than your skin's pH. Both can lead to a painful chemical reaction on your skin. 

An allergy happens when an ingredient in your deodorant does not agree with the chemistry of your skin and simply irritates it immediately or over time. 

How does a chemical burn happen and how to avoid it from a deodorant? 

Chemical burns happen when you put an irritant on your skin such as an acid or base. It's easy to avoid chemical burns. Read the label and understand the active ingredients in the formulation.

Most natural deodorants stop body odour with the help of a weak base or a weak acid or fermented fungi as the main active ingredient.

• The most commonly used weak bases are baking soda and/or magnesium hydroxide.
• The most commonly used weak acids are mandelic acid and glycolic acid. 
• The most commonly used fermented fungi are Saccharomyces ferment.

A weak base dissolves poorly in water and a weak acid does not ionize fully in water. Meaning there is no free base or acid available to cause a chemical reaction. However, if you allow them to soak in sweat for days together, they will cause a painful reaction.

The pH of your naked underarm is between 5.5 to 6. This pH is quite cozy for bacterial growth. The bases will raise the pH of your skin and the acids will lower the pH of your skin. By raising or lowering the pH in your underarms, your deodorant is creating a hostile environment for bacterial growth. The ferment is also acidic and it has live enzymes that break down odour causing compounds. When using a deodorant that has an acid or a base as an active ingredient, observe the following,

• Give your underarms a good scrub in the shower every day and make sure there is no residue from the previous day left in your underarms.
• Trim or shave your underarm hair. Hair is porous and will trap particles from your deodorant. This can lead to a chemical reaction later. 

While baking soda can be used in small quantities to balance the pH of formulations, it is not skin safe or suitable as an active or main ingredient. If your deodorant contains baking soda as the main ingredient, the chances of you getting a chemical burn are 100%. If your deodorant from the previous day is not washed away properly, some of it will react with your underarm sweat and will cause a reaction on all skin types. It is only a matter of when or how soon. There are no exceptions. Commercial antiperspirant deodorants use a Lewis acid like Aluminium chlorohydrate. If you are using one with an ingredient like this, you may want to follow the same precautions. 

How to treat a chemical burn?

Don't treat a chemical burn yourself. Consult your doctor immediately.

The second type of natural deodorant contains an antibacterial agent that uses its physical property to influence chemical behaviour. Super Deodorant is the best example of this kind of deodorant. In Super Deodorant, pure silver is present in very small quantities. When silver clings to your skin, it will continuously release silver ions and destroy malodour causing bacteria. We use magnesium hydroxide to balance the pH of our formulation and make it more skin-friendly. While none of the ingredients used in Super Deodorant will cause a chemical burn, we tell our customers to keep up decent personal hygiene while using our product. At least wash your underarms once every day. 

How does an allergic reaction to natural deodorant happen and how to avoid it?

Any deodorant can cause an allergic reaction if you are allergic to one or some of the ingredients present in the deodorant. I am allergic to almonds and I cannot eat them. But I can use almond oil topically without issues. I am allergic to some protein in almonds. As the oil does not contain protein, it doesn't hurt me when I use it on my skin. Almond or not, every time, I buy a new skincare product, I do a patch test for 24-48 hours before putting the product to full use. Make it a habit to read the label patiently and do a mandatory patch test. Another good tip is to choose a formulation with fewer ingredients. If you can, go for a deodorant without baking soda or essential oils or fragrance. If you are allergic to yeast, avoid deodorants with ferments such as Saccharomyces.

If you are using deodorant with mandelic acid/lactic acid/glycolic acid or another alpha hydroxy acid, limit use to once per day and use very little product.  Long-term overuse could cause redness, swelling, itching and flaking.

Sometimes you may experience sensitivity after a few days of use in the form of an itchy bump or a rash in your underarm. It could be a one-off incident or a real allergy. The only way to be certain is by doing a divide and conquer. Apply deodorant to one underarm and leave the other underarm alone for a day or two and see what happens. If you experience any discomfort, discontinue use immediately. If you are in the habit of moisturizing your underarm before applying deodorant, you may want to give the moisturizer a break in the underarm region. 

How to treat an allergic reaction?

Stop using the product and leave your underarms alone. It should heal on its own but if the discomfort continues for more than 1 or 2 weeks, seek medical help.