Clinics bill you on the spot for any service given, including dispensing prescribed medication.Sometimes medication may not be available at the clinic. In such cases, ask the nurse to help you locate a pharmacy with stocks available. Medication can be ordered within one or two days. If you need special drugs from overseas it is wise to bring an ample supply (with doctor's certificate!) until you have ascertained availability in Singapore. Generally clinics and pharmacies are well stocked.   Many over the counter drugs available overseas cannot be purchased in Singapore unless you have a prescription. This includes oral contraceptives, sedatives, sleeping pills and tranquilizers. Some brands may be sold under a different name. Consult the pharmacist. Expect drugs to be relatively expensive in Singapore, as there is no government subsidy.