High blood pressure 

The usual initial Sectral dosage for mild to moderate high blood pressure is 400 mg per day which may be taken in a single-dose or in two doses of 200 mg apiece.  The usual daily Sectral dosage ranges from 200 to 800 mg. People with severe high blood pressure may take up to 1200 milligrams per day divided into two doses.  Sectral may be taken alone or in combination with other medications for high blood pressure. 

Irregular heartbeat

The usual starting Sectral dosage for irregular heartbeat is 400 mg per day divided into two doses.  Your doctor may gradually increase the dosage to a range of 600 to 1200 mg per day.  If your physician decides to stop this high blood pressure medication he will gradually reduce the dosage rather them stopping it abruptly. 

Dosage for children: 

The effectiveness and safety has not been established for children. 

Sectral dosage for older adults: 

Your physician will determine your dosage depending upon your particular circumstances, but will not usually exceed 800 mg per day. 

Overdosage: 

Any medication taken in excess of the prescribed amount can be dangerous to your health.  If you believe you may have overdosed you should seek medical attention immediately. 

There is little specific information related to overdosage on Sectral; however overdose symptoms seen with other beta-blockers may include: 

Difficulty breathing, extremely low heartbeat, irregular heartbeat, low blood pressure, low blood sugar, seizures, severe congestive heart failure