You need to self-coach yourself through these things. I promise you that needles are not reused so when this thought pops into your head you need to say "NO, NEEDLES ARE NOT REUSED, NOW MOVE ON." You would be surprised how effective yelling at yourself in your head is. You need to replace those negative thoughts with positive ones. We get so caught up in the fictions that we can't see the facts anymore.
Here is a breathing technique for you to practice as well. I use this when I start to think I might have a panic attack and I can usually stop it from happening.
You take a deep breath in through your nose, hold it for 5 seconds and count this out in your head, then let it all out through your mouth. Practice this while you are laying down with your hands on your stomach so you can feel the rise and fall of it with each breath. This will help calm you down. You can do this breathing in any situation and nobody will even know you are doing it. I use the self-coaching and breathing in the car all the time.
Take care.
I have no issue like that i have not been ever found or treated for ocd. Please tell me how can i overcome this problem.
Can you tell me what should i do?
You are stuck in the viscious cycle of doubt. Needles are not reused. Have you ever been diagnosed with OCD or Anxiety in general? It is hard to say whether this is OCD or Health Anxiety.