We use it and yes, we sometimes do have problems with the teats blocking. We use Dr Browns size 3 teats and I always mix with warm water. I find that for best results, I add freshly boiled water to cooled boiled water (I make up 5oz bottles and let them cool and then add 2oz of boiling water when ready to feed). Also, I shake them for about 20 seconds which seems like ages when you're doing it (!!) but it's the only way to get it to dissolve. Even then, sometimes the teats block. I know Dr Browns do a Y-cut teat for thicker liquids but I don't think it's actually the milk that's thick, it just doesn't mix easily. xx