A promotion email from Groupon offering discounted cosmetic surgery, including breast enlargement, has been banned for "pressuring" consumers into hurriedly making potentially life-changing decisions in just a few hours.

The email offered discounts of well over 50% on operations at a clinic in Manchester if consumers booked before midnight on the day the deal was sent out.

Recipients of the email could click through to "fine print" that stated regulations such as that purchasers had to be over 18 and that there is an initial consultation before any procedure takes place. The deal was sent out in May with surgery to take place by 28 November.

The Advertising Standards Authority received a complaint from a member of the public and the Independent Healthcare Advisory Service that the Groupon deal was irresponsible "because it encouraged recipients to hurry into a decision to purchase cosmetic surgery".

Groupon said it did not believe the promotional email "encouraged a frivolous or rushed decision to purchase the voucher".

It said the offer was available to buy for 24 hours only, a decision made in conjunction with the clinic that provided the surgery, and that the tactic of a time limit was "an indicator of their business model and was not indicative of pressure purchase tactics".

Groupon said the steps involved to get to the point of surgery, such as a consultation and being able to request a refund, meant that by the end of September 48 of 186 consumers had cancelled their vouchers.

The ASA pointed out that the marketing and ethical code run by the British Association for Aesthetic Plastic Surgeons (BAAPS) prohibited ads that offered discounts linked to a deadline date for booking appointments "or other date-linked incentives". The practice also goes against the good practice guide of the General Medical Council.

"We considered that the decision to undergo physically invasive procedures was one that required substantial consideration," said the ASA. "We noted consumers only had 24 hours in which to buy the voucher and because of that, we considered that consumers buying the voucher would have already financially and mentally committed themselves to going ahead with a procedure."

The ASA said that the "very limited time in which consumers had to buy the voucher pressured consumers into making a decision to (to all intents and purposes) purchase cosmetic surgery".

The ASA said the email promotion was irresponsible and banned the ad.

"We have moved quickly to address the ASA ruling and have already changed subsequent plastic surgery deals to extend the period they are available for," said a spokeswoman for Groupon, adding that the company has reviewed its process for offering such deals and has extended the expiration time limit to "at least three days" on average.

"Groupon endeavours to ensure that all of our advertised deals meet the highest possible standards and are both responsible and provide clear information for our customers," said the spokeswoman. "We are always striving to make the Groupon experience the best it can be and to ensure that the deals we offer are great value for our customers."

• To contact the MediaGuardian news desk email editor@mediatheguardian.com or phone 020 3353 3857. For all other inquiries please call the main Guardian switchboard on 020 3353 2000. If you are writing a comment for publication, please mark clearly "for publication".

• To get the latest media news to your desktop or mobile, follow MediaGuardian on Twitter and Facebook.