Tell your doctor before using suxamethonium if you have or had tetanus, tuberculosis, other severe or long standing infection or illness, cancer, anemia, malnutrition, liver or kidney problems, auto-immune diseases (multiple sclerosis), an underactive thyroid gland (myxoedema), muscle disease (such as myasthenia gravis), a blood transfusion or a heart-lung by pass, been in contact with insecticides, allergic reaction to any muscle relaxant given as part of an operation.