Answer: To kill the bacteria causing the illness
Step-by-step explanation:
When a person takes antibiotics, the bacteria causing diseases will be severely hampered in its operations which will lead to the symptoms of the disease reducing. The bacteria will not die until the drug is taken as prescribed which is why the full dosage must be taken.
If it is not, the bacteria can regain strength and start causing sickness again except this time, it may grow an immunity to the antibiotics which means that an even stronger dosage of antibiotics will be needed.