Bad effects of taking the pill: 1. Adverse reactions after taking the pill: In the early stages of taking the pill, some people will have early pregnancy-like reactions: dizziness, headache, fatigue, drowsiness, loss of appetite or nausea and vomiting. In addition, menstrual disorders, stretch marks on the skin, weight gain, breast pain and increased leucorrhea may occur. 2. The pill may aggravate thrombotic diseases, congestive heart failure, blood disorders, malignant hypertension and other diseases. 3. The hormones in the pill may promote the development of tumors. Precautions for the use of birth control pills: 1. Women with hyperthyroidism are advised not to use birth control pills during the treatment period. 2. Women suffering from chronic headache, especially migraine and vascular headache, should not use them. 3. Lactating women are prohibited.