The main goals of drug development are efficacy and safety. Since all medications can do damage as well as aid recovery, the issue of safety is relative. The difference between the usual effective dose and the dose that causes serious or life-threatening side effects is called the margin of safety. It is desirable that the margin of safety be wide; But when a serious condition is treated, or when there are no other options, then often a limited margin of safety must be accepted. If the drug's usual effective dose is also toxic, doctors use the drug only if the condition is serious and there is no safer alternative. However, the most useful drugs are effective, and most are safe. Penicillin is one of these drugs. With the exception of people who are allergic to penicillin, it is virtually non-toxic, even when used in large doses. On the other hand, barbiturates, which were commonly used as a sleep aid, can often interfere with breathing, cause a dangerous drop in blood pressure, and even cause death if taken in excessive doses. Newer sleep aids, such as temazepam and zolpidem, have a wider margin of safety than barbiturates. It is not always possible to manufacture effective drugs with a large margin of safety and few side effects. As a result, some drugs must be used even if their safety margin is very limited. For example, warfarin, which is used to prevent blood clotting, can cause bleeding; But it is used when absolutely necessary, with the need to bear the risks of its use. People who take warfarin need frequent check-ups to see how much of the drug's blood-thinning effect is needed, and to investigate whether the dose is appropriate, increased, or decreased to achieve a treatment goal. Clozapine is another example of this. This drug is often useful in people with schizophrenia after all other drugs have failed. But there is a serious side effect of using clozapine. It may reduce the production of white blood cells, which are needed to prevent infection. Because of this risk, people taking clozapine should have regular blood tests while they are taking this drug. To help ensure their treatment plan is as safe and effective as possible, make sure they tell their health care providers regularly about their health history, medications (including over-the-counter) and dietary supplements (including medicinal herbs) they are currently using, and any other relevant health information So. In addition, a person should not hesitate to ask the doctor, nurse, or pharmacist about treatment goals, side effects and other problems that may occur, and the extent to which they can be involved in implementing the treatment plan.