It depends on what kind of Nasal polyp it is. If it's non bleeding polyp and smaller in size, then Neti can help. You may start with Jala neti for few weeks. Thereafter it may be followed by catheter neti. If you get good results, you may go ahead with cotton sutra. But will have to do Neti more frequently like on daily basis or alternate days. However, we suggest that you must consult your physician to get your nasal polyp diagnosed before you practice neti.
Feel free to write for further clarifications on the issue.
Related: Unlock the Secrets of Jala Neti - The Headache Free Technique
Neti Pot - Generally, Copper Neti Pots are recommended. But now-a-days, good quality copper pots for neti are not available in the market, even at Amazon online market place - we could not find in the Amazon search for Copper Neti Pot. We tried with steel made neti pot too, and got disappointed with feedbacks thereof. The neti pots are better available at any of your local Yoga Institute like Morarji Desai Institution of Yoga at New Delhi, etc. The one we found that at amazon is cheap , can be easy to keep during travelling is small plastic neti pot at amazon. That works fine.
If you want to use to quality ceramic neti pot, that is available by Himalayan Institute at amazon, but yes it is expensive, even beyond the copper neti pot, but it is very customized to the nostrils and handling while doing neti. We have good experience of it as we have been using it for a long time. But again do not forget that it is ceramic one, it has to be handled with care and can be broken.
