Jodie Sanderson, of Kenilworth Avenue, Galashiels, made the grim discovery while out playing with her three-year-old son Lewis in a communal area outside their block of flats in Langlee.
She revealed she is petrified the toddler could have ended up contracting HIV if he was jabbed by the deadly syringe which was left dumped on their doorstep by drugged-up yobs who are making their lives a misery.
Speaking to the Border Telegraph this week, Jodie, who revealed she is now too scared to let her son play outside alone, said: "It's disgusting. My worry is, if I wasn't with him, he could have ran ahead and actually picked it up himself. It was just lucky that we spotted it before he did."
The mother-of-three, who works as a security officer at Asda in Galashiels, blamed the local housing association for moving drug addicts into their neighbourhood. And she was critical of their response after attempting to contact them to report the find and ask for advice on safely disposing of the needle.
Jodie, who claimed drug addicts are turning their home into a no-go area, said: "I've lived here for nine years and never had any problems like this until Scottish Borders Housing Association started moving tenants who are known drug addicts in to a block full of children. It's just not right."
But she added: "When I called them to report it nobody seemed interested. I got passed round five times to five different people and had to keep explaining myself over and over again. I was quite disappointed."
It is just the latest in a series of dirty needles found dumped in residential areas of the Borders in recent weeks which prompted police to warn addicts to be more responsible when disposing of their drugs paraphernalia.
The Border Telegraph previously reported how a doting dad was left shocked after it took community wardens almost 24 hours to respond to a report of a needle found outside his home in nearby Winston Place, also in Langlee.
Jodie said: "This used to be a great flat but I'm not happy living here anymore. This was the best flat out of the whole street, there was never any trouble, never any bother, and then they stuck in some riff raff and it's gone downhill and there is arguing and fighting."
But she added: "A lot of young kids live in this block and they can't go out into their garden now."