Therefore, you must not use magnets near pacemakers
It cannot be emphasized enough that you must not use magnets near people with pacemakers. A distance of min. 20 cm. is necessary, but to be safe it is best not to do so.
Pacemakers can switch off on magnetic contact
The electronics in pacemakers are sensitive to strong magnets, and in the worst case can put a pacemaker out of action. Obviously, a larger magnet in close contact with the skin is needed for this to happen, but since it can be a matter of life and death for people with pacemakers, there is no reason to be overconfident.
Many of the smallest neodymium magnets are used in everyday things that are not directly dangerous for people with pacemakers, but are magnets a la these tiny neodymium magnets: