I stopped taking them 5 yrs ago. I've noticed that I can't feel the glow of alcohol. I get the headache and feel groggy the next day, but no buzz. I had dental work done and the dentist couldn't get me numb. The nitrus had no effect at all. I thought he forgot to turn it on. He also gave me a prescription for codeine, but I stopped taking it because I didn't notice a differance. He gave me a dire warning and told me they were really powerful. I felt... nothing! Meanwhile, my husband took one and was on cloud 9! So unfair! It's frustrating and makes dental work hell. I just want the same opprotunity as everyone else to get tipsy. Has anyone heard of thsi before? What do I do?