Most of the chemotherapy drugs are strong and taking too little or taking stronger doses of the medication will harm you. For this reason, your medical oncologist calculates the chemotherapy doses carefully after examining your body and cancer. The overall dose depends on: Your body weight Age Medical history Body tolerance capacity The chemotherapy is usually given in regular intervals called cycles. A cycle may be a dose of one or more drugs on one or more days, followed by several days or weeks without treatment. This gives normal cells time to recover from the drug side effects. Some drugs may be given continuously while others might be given certain days in a row followed by a period of rest.