What is a drug? It is a chemical substance that, when ingested, brings about a change in the physiology or psychology of an organism. The drug is usually distinguished from food or substance that is used for ingestion. The ingestion of drugs may be by inhalation, injections, smoking, ingestion, ingestion by patch on the skin, suppository, or dissolve under the tongue. Regarding pharmacology, a drug is a chemical substance whose structure is usually known and which, when administered to a living organism, causes a biological effect. Traditionally medicines have been obtained by extraction from medicinal plants, but recently they have also been obtained by organic synthesis. Drugs can be used for a limited duration of time or regularly for chronic diseases. Explain in detail the signs, symptoms, and drugs used for the treatment of at least five tropical diseases. Major tropical diseases include malaria, schistosomiasis, lymphatic filariasis, Chagas disease, and Leishmaniasis. Fortunately, there are drugs that relieve the signs and syndromes, or we can even treat these diseases with the pharmaceutical route.