Yes Graham, I think it is very likely.
As an airline pilot (or many other types of professional pilot), you cannot place your colleagues or your passengers in any degree of unreasonable jeopardy. When it comes to chronic medical conditions, there are many cases that may be acceptable from the "reasonable risk" standpoint. For example, Hypertension (high blood pressure) is a chronic condition that usually involves long term (lifetime) medication. However in a case where the controlling medication is forgotten, lost, or otherwise not taken, it is very unlikely to result in short term incapacitation. That may well not be the case with somebody who is susceptable to severe allergic reaction, particularly where the triggers are likely to be commonly encountered.
The regulator in these matters in the UK, is the medical division of the Civil Aviation Authority. In other countries the regulator is usually also that countries Civil aviation adminstration. They and they alone are responsible for setting the acceptable standards. There is very often a flexibility and individual assesment made of conditions that may actually or potentially be disqualifying, and often an individual assesment is made with the consultation of medical specialist reports. However only the CAA will be able to properly advise you in this respect. Any advice given here is opinion or anecdotal, and as such it would be unwise to base any hard career choices on what is simply general comment or opinion.
When you are old enough to qualify for a licence, it would be very prudent to first submit to a class 1 medical. It isn't particularly cheap, and the result might he disappointing, but the cost is very small in relation to the potential sums involved in flight training.