Taking cold medicine will not affect your period. The flu is caused by viruses or bacteria, and taking antiviral and antibiotic drugs does not affect hormone secretion and therefore does not affect menstruation. Menstruation is affected by emotions, stress, diet, cold, exertion, etc. If menstrual cycle fluctuations occur during a cold, it is normal because the hormone levels change due to decreased resistance, poor rest, and poor digestion due to illness, which affects endocrine secretion and is not caused by medication. In particular, a cold can cause delayed menstruation, so pay attention to rest after the cold, take medication on time as prescribed by the doctor, and drink more warm water to promote excretion, so as to minimize the impact on the body. If you have a sexual life, do not exclude the possibility of pregnancy and wait patiently for your menstruation to return to normal.