If you have already poured caustic soda and it did not work, do not add any other chemicals (especially bleach or ammonia). Call a professional plumber immediately and tell them exactly what you used.
Caustic soda is a fantastic chemical for dissolving organic clogs in metal sink drains. But in a porcelain toilet, the risks of cracking the bowl, injuring yourself, or ruining your septic system far outweigh any benefit. Put the caustic soda away and reach for a plunger or an auger instead.
If you’re facing a stubborn clogged toilet, you might have come across a suggestion to use caustic soda (sodium hydroxide). It sounds like a powerful solution—because it is. But before you pour that heavy-duty drain cleaner into your porcelain throne, you need to understand exactly what happens, the serious risks involved, and the safer alternatives.