It means literally “do not put your salts in empty capsules.” Meaning, do not buy your own empty capsules and put salt inside them and swallow it.
Putting salts in empty capsules is not the same as buying supplements in capsule form.
Pre-manufactured electrolyte supplements, if you buy from a reputable source, should be formulated to be safe for your stomach lining. They should be designed to dissolve quickly, evenly, and not stick to your stomach lining.
To back what others have said: if you buy premade tablets, those should be fine. It’s when you are DIY is where problems can come in. That concentrated dose can really harm your gut. Speaking from experience: it basically burns a spot into it.
Source: dummy me did it and it hurt so bad I passed out. Then for about 3 weeks it felt like an ulcer was in there. And all I did was basically a watered down shot of salt and no salt.
I have a little “tin” box with a sliding lid.
In that i have some flakey sea salt. I like my finger and dump it in. A few pieces of salt sticks to my finger. Easy peasy.
Why make everything too complicated?