A young woman may sue McDonalds after she spilt her drive-thru hot chocolate on to her lap.

Sam Smith could even need plastic surgery after the 85 degrees drink, bought from the restaurant, fell into her lap, scalding her with second degree burns.

The 22-year-old says a trip to the loo is now 'torture.'

The estate agent blames the fast food chain for filling the piping hot drink too high in the cup, not fixing the lids on correctly and giving her two hot chocolates in an inadequate tray holder.

Sam suffered painful blisters and is likely to be off work for six weeks as it heals.

The professional and her mother Alison are even contemplating an operation to fix the wounds and are considering taking legal advice against McDonalds.

Sam said: "The design of the cup was wrong.

"They were too full, and there was a sharp bend and a speed bump in the drive-through, for some strange reason. I can't walk properly now, and shuffle around like a frog.

"Going to the toilet is excruciating. My mum threw a bottle of water over me when it happened, but the pain in my groin as indescribable."

Mother Alison said: "Sam's friend did exactly the same thing four years ago, but she was luckier as it was on her thigh.

"I'm going to start a campaign against McDonalds drive-thrus and hot drinks. It's such a delicate area for this to happen. This is not about any money. Sam is not an attention seeker at all.What would be the outcome if a baby was burnt like this?"

Sam, from Litherland has gone to specialist burns hospital in Whiston for expert help.

A spokesman for McDonald’s said: “We are sorry to hear that Mrs Smith’s daughter sustained an injury following her visit to our drive-thru restaurant and we hope she makes a speedy recovery.

“The safety and wellbeing of our customers and employees is our first priority and all of our restaurant crew are trained to serve hot drinks in a safe manner, with lids firmly secured. We have launched a full investigation and our customer services team will be in touch with Mrs Smith.”