If the target fails its saving throw, then they get another one periodically to throw off the charm effect. If the creature is currently being threatened or attacked by the caster or his or her allies, however, the creature is more likely to resist the effect of the spell.

Note also that the caster must be able to speak the person's language to communicate commands, or be able to communicate and be understood with gestures. Any act by the caster or apparent allies that threatens the charmed person breaks the spell. You gain a +2 insight bonus on Diplomacy checks made to interact with the target for every caster level, to a maximum of +20 at 10th level.ДЄ charmed person never obeys suicidal or obviously harmful orders, but he or she might take an action resulting in death if it will save the caster's life. The caster can try to give the subject orders, but the subject is unlikely to do anything outside its normal behavior pattern, this requires a Diplomacy check to get the subject to perform a contrary act. The spell does not enable the caster to control the charmed person as if he or she were an automaton, but he or she perceives the caster's words and actions in the most favorable way. This charm makes a humanoid of medium size or smaller regard the caster as his or her trusted friend and ally. Charm person is an enchantment spell that makes the subject a friend of the caster.Д¬harm Person is a common spell in the Realms

Charm person wikibot