How Do Bath Bombs Fizz? The Science Behind Your Favourite Self-Care Item Explained

Stocksy / Sally Anscombe

Bath bombs are just the best after a long, boring day at work, aren't they? It's so easy to run a bath and just chuck one in, sit back and wait for the glorious smells and colours to take over. If you're inquisitive like me, you may have asked yourself before, 'How do bath bombs fizz?' or maybe even wondered if you can make them yourself at home. Keep reading to find out...

How Do Bath Bombs Work?

Interestingly, bath bombs are actually pretty similar to things like Alka Seltzer and soluble aspirin. According to BBC Focus magazine They all contain sodium bicarbonate and citric acid, which causes the 'fizz'. When these ingredients are dry, they don't react. But when they get wet, the citric acid and sodium bicarb dissolve and react with one another, forming sodium citrate and carbon dioxide. The carbon dioxide is the thing that bubbles and breaks the bath bomb up.


easternblot on YouTube

Want to know more? This video by Eastern Blot explains the science behind the bath bomb, as well as showing you how to make your own, which leads nicely onto my next question...

Can You Make Your Own Bath Bombs?

Yes, absolutely! I recommend starting on YouTube and watching a handful of tutorials before you start. Easternblot's video shows how to make a bath bomb with the following ingredients: baking soda, citric acid, corn starch, epsom salt, water and oil. She also later notes in her written recipe that it's worth also adding in drops of perfume and/or food colouring for fragrance and fun colours. And if you don't fancy trying to find all of those ingredients down at your local Tesco you can pick up a bath bomb making kit.

All you need to do is mix the dry ingredients all together, then mix the wet ingredients together, before very slowly adding the wet mix to the dry to form a wet sand consistency. Then, simply leave the mix in a bath bomb mould or small bowl to dry out overnight, then remove it from the mould for a day or two longer et voila!

Five Great Bath Bombs If You're Not Really Into The Whole DIY Thing:

Lush Sex Bomb Bath Bomb



Super soothing and a little bit sexy, this bath bomb is the perfect antidote to a long, boring day. With hints of jasmine, ylang ylang and clary sage, it smells as good as it looks.

Sol De Janeiro Bum Bum Limited Edition Bath Bomba


Sol De Janeiro/Cult Beauty

If you're a fan of Sol De Janeiro's incredible-smelling cream and shower gel, this bath bomb will be right up your street. It smells like fresh mangos mixed with caramel and pistachio, so yeh, pretty awesome.

Lush Intergalatic Bath Bomb



If you want your bath to turn into a galaxy of bright and bold colours, this is the product to pick up. It also smells super refreshing, uplifting and green with vetivert and cedarwood.

The Body Shop Mango Bath Bomb


The Body Shop

Super affordable and perfect for a cosy Friday night in treat, The Body Shop's Mango bath bomb is everything you've dreamed of and more.