Sultamicillin, the active ingredient in your medication, is an antibiotic and does not typically cause heavy menstrual bleeding or directly affect your menstrual cycle. However, the physical stress of the infection your body is fighting can sometimes temporarily disrupt your hormonal balance, leading to slight changes in your period. Additionally, if you are using hormonal birth control, some antibiotics can occasionally cause breakthrough spotting. Please rest assured that this is generally temporary. If your heavy bleeding persists, is severe, or is accompanied by severe pain, please consult your healthcare provider to rule out other underlying causes.