Getting so anxious

Hi, I don’t how to describe this but I keep getting a lot of anxiety to do with getting addicted to drugs? I really honestly don’t know how to explain it? I’ve done drugs wayyyyyyy in the past, never got addicted to them ever, would never do them again. 

But I have this big amount of worry that what if one day I become a drug addict? It’s really weird I know, I really don’t know where it’s come from it’s just causing me a lot of distress and I’m just scared that one day I will get addicted to them, but I don’t even want to do drugs? That’s the weird thing about it!? It is just causing me anxiety and I honestly do not know why? I do not want to do drugs I do not feel the need to do them so why is this thought scaring me so much? 

I have tried to google it to find some solution but it doesn’t really say anything, I already suffer with anxiety as it is. 

Please can someone let me know what they think and maybe why I feel like this? It’s really distressing me! It’s just worrying me I just keep thinking ‘what if in the future I become a drug addict?’

What drugs are you talking about ?