The warning from Waitrose Good Food Guide editor Elizabeth Carter comes as surveyors Morgan & Clarke dubbed the move as the "death of the specials board and menu blackboard".
The upcoming legislation is binding on the UK Government from 13 December 2014 and is designed to inform and protect consumers with a focus on 14 named major allergens and intolerance-causing substances. It will require publicans and others in the hospitality industry to provide allergen details on freshly prepared food.
"Whilst it was hoped that simple notification on a chalk blackboard or specials’ board stating "dishes may contain allergens; refer to our menu" would be OK, this will definitely not be sufficient for a specials’ board or a menu that is only set out on a blackboard," said a spokesman for Morgan & Clarke.
"It is quite likely that specials will, individually, have to carry details of the dish contents."
Carter said: "It does kill kitchen spontaneity. It would be a shame if specials boards went, as you often find more interesting dishes there.
"I don’t know how chefs can get around this minefield. A smart chef could maybe work out a basic recipe that he [or she] can work with the seasons, avoiding some named allergens, but you can’t expect chefs to cover everything.
"Restaurants house totally different kitchens from those making supermarket and pre-packaged food. It isn’t a crisp, clean, factory operation, but an environment with different sections when making food from scratch.
"It is hard enough for chefs to cover all the health and safety and hygiene regulations. It’s too much — very Big Brother — and the onus has to be on the customer.
"I have sympathy for people with allergies but it is also about common sense. Good restaurants check for allergies on booking.
"I just can’t understand why anyone with a life-threatening allergy would play Russian roulette in a restaurant."