Side effects
It is generally accepted that the health risks of oral contraceptives are lower than those from pregnancy and birth, and "the health benefits of any method of contraception are far greater than any risks from the method". Some organizations have argued that comparing a contraceptive method to no method (pregnancy) is not relevant—instead, the comparison of safety should be among available methods of contraception. Common
Different sources note different incidence of side effects. The most common side effect is breakthrough bleeding. A 1992 French review article said that as many as 50% of new first-time users discontinue the birth control pill before the end of the first year because of the annoyance of side effects such as breakthrough bleeding and amenorrhea. A 2001 study by the Kinsey Institute exploring predictors of discontinuation of oral contraceptives found that 47% of 79 people discontinued the pill. One 1994 study found that women using birth control pills blinked 32% more often than those not using the contraception. Another 2011 study, presented data that indicated 74% of the women experienced weight gain, and 51% recorded an appetite change. Another 47% of the women recorded vaginal dryness and 48% experienced low sex drive.On the other hand, the pills can sometimes improve conditions such as dysmenorrhea, premenstrual syndrome, and acne, reduce symptoms of endometriosis and polycystic ovary syndrome, and decrease the risk of anemia. Use of oral contraceptives also reduces lifetime risk of ovarian and endometrial cancer.
Hypermagnesemia is an electrolyte disorder in which there is a high level of magnesium in the blood. Symptoms include weakness, confusion, decreased breathing rate, and decreased reflexes. Complications may include low blood pressure and cardiac arrest.It is typically caused by kidney failure or is treatment-induced such as from antacids that contain magnesium. Less common causes include tumor lysis syndrome, seizures, and prolonged ischemia. Diagnosis is based on a blood level of magnesium greater than 1.1 mmol/L (2.6 mg/dL). It is severe if levels are greater than 2.9 mmol/L (7 mg/dL). Specific electrocardiogram (ECG) changes may be present.Treatment involves stopping the magnesium a person is getting. Treatment when levels are very high include calcium chloride, intravenous normal saline with furosemide, and hemodialysis. Hypermagnesemia is uncommon. Rates among hospitalized patients in renal failure may be as high as 10%. Signs and symptoms
Symptoms include weakness, confusion, decreased breathing rate, and decreased reflexes. As well as nausea, low blood pressure, low blood calcium, abnormal heart rhythms and asystole, dizziness, and sleepiness. Abnormal heart rhythms and asystole are possible complications of hypermagnesemia related to the heart. Magnesium acts as a physiologic calcium blocker, which results in abnormalities of the electrical conduction system of the heart. Consequences related to serum concentration:

4.0 mEq/L – Decreased reflexes
>5.0 mEq/L – Prolonged atrioventricular conduction
>10.0 mEq/L – Complete heart block
>13.0 mEq/L – Cardiac arrestThe therapeutic range for the prevention of the pre-eclamptic uterine contractions is: 4.0–7.0 mEq/L.