Doctors say thresholds for "normal" blood pressure and cholesterol levels have been set so low healthy people might be put on unnecessary medication.
High blood pressure can be a sign of disease
The European Society of Cardiology drew up guidelines on cardiovascular disease prevention in 2003.
However, GPs Steinar Westin and Iona Heath say under them as many as 90% of people over 50 could be labelled at risk, and end up on drugs.
The study is published in the British Medical Journal.
The GPs are concerned that many people might end up taking drugs which would be of little benefit to them, but which are expensive and associated with side effects.
People 'at risk'
The guidance sets the following thresholds:
Blood pressure above 140/90 mm Hg
Serum cholesterol of 5 mmol/l
However, the European Society of Cardiology said the concerns were based on a "fundamental misunderstanding" of the purpose of the guidance.
When the guidelines were applied to adults in Norway, 76% of the population were defined as being at risk, including half of all 24-year-olds.
This is despite the average life expectancy in Norway being 78.9 years.
The researchers say the proportions are likely to be even higher if the same thresholds are applied to the UK - where average life expectancy is 78.1 years.
Not only do the drugs potentially cause physical side effects, the researchers are concerned there may be psychological effects from being labelled as vulnerable to heart disease.
Writing in the BMJ, the researchers say: "We have far too little understanding of the psychological impact and the wider health consequences of being labelled at risk."
Doctors have raised concern about too many people being labelled as being at risk before.
In 1999, more than 800 doctors, pharmacists and scientists from 42 countries signed an open letter expressing concern that World Health Organization hypertension guidelines would result in increased use of drugs at great expense and for little benefit.
Ways to cut heart disease risk
Take more physical exercise
Reduce saturated fat and salt in your diet
Eat at least five portions of fruit and vegetables a day
The European Society of Cardiology issued a statement saying the guidance was intended to help identify people who could benefit from modifying their lifestyle to reduce risk - not to label people as sick.
The guidance did not recommend intensive therapy for people whose blood pressure and cholesterol levels were higher than the threshold levels.
"In such subjects, simple lifestyle measures are the basis of management with drugs held in reserve for only the highest risk people."
The statement also questioned the merits of the Norway study, and said other studies did not estimate that such a high number of people would be defined as being at risk.
Cathy Ross, medical spokesperson for the British Heart Foundation, said: "The limits suggested should act as guidelines in the assessment of risk and should be used in combination with lifestyle advice.
"Furthermore, it is better for patients to be made aware of their risk, and to take action to lower it, than to keep the threshold high simply to avoid an unfortunate 'label'."