Consumers with a pre-existing health condition can still switch health insurer without penalty.
The Health Insurance Authority says there has been a 14-fold rise in calls to its helpline and visits to its website.
It has stressed that some older people who are being treated for a medical condition are afraid they cannot switch to another provider, but this is not the case.
Consumers are being encouraged to switch after the VHI said it was increasing the cost of some of its plans by 45pc.
The HIA says many of those contacting the authority, particularly older people, were confused and mistakenly thought they would be refused cover if they were already suffering from a medical condition.
HIA boss Liam Sloyan said: "Consumers can be assured that any person can switch health insurance product without penalty, while maintaining existing benefits."
A consumer could even switch health insurance provider if they phoned from a hospital bed while having treatment as long as they opted for a health plan with similar benefits.
Mr Sloyan urged consumers to visit the authority website -- www.hia.ie or phone 1850 929166 -- to get advice.
The HIA will also be investigating reports that the VHI has been telling its customers they cannot move back to their original health plan within one year if they opt for a less expensive corporate plan.
Corporate plans are cheaper than individual health plans and often have better benefits.
They are available to everyone despite the fact that they are only marketed at companies taking out health plans on behalf of all of their staff.
Thousands of VHI customers are opting for a corporate plan equivalent to Plan B options after the company said the adult premium would rise by €444 to €1,430 from February 1.
The VHI said yesterday that people in a group scheme would have to come out of that scheme and make their own arrangements for direct payment.
Health insurance experts said this appeared to be a change of tack as up to now the insurer was allowing people to remain in a group scheme -- where their employer deducts their premium monthly while swapping an individual plan for a corporate one.