Chemotherapy is administered to treat various types of cancers. Cancer is a life-threatening disease caused by the uncontrolled growth of abnormal cells. Cancer cells or malignant cells can spread to other parts of the body through the blood and lymphatic system. There are various types of cancers, such as lung cancer, breast cancer, prostate cancer, colon cancer, skin cancer, liver cancer, etc. Major categories of cancer are carcinoma, sarcoma, leukemia, lymphoma, and myeloma as well as cancers of the central nervous system. If cancer is diagnosed in its early stage, the chances of healing are more. How Does Chemotherapy Work? Chemotherapy is the most common treatment method for different types of cancers. It involves the use of chemicals to prevent the growth of cancer cells. The drugs used in this therapy are known as 'anticancer drugs', and they destroy the malignant cells. These drugs are classified into various groups such as alkylating agents, antimetabolites, anti-tumor antibiotics, topoisomerase inhibitors, mitotic inhibitors, corticosteroids, and related medications. Chemotherapy can be administered intravenously, given orally in the form of a pill, or injected into the body cavity. Generally, this treatment is given in cycles. Each cycle is administered every 1 to 4 weeks, and there is a rest period between every chemo cycle. The chemo drugs act by killing the cancer cells, thereby preventing them from spreading and slowing their growth and multiplication. Many a time, a combination chemotherapy of two or more chemo drugs may be given at a time. Some drugs restrict the effect of certain hormones in the body. The therapy can be given before or after surgery. If given before surgery, it is called neoadjuvant chemotherapy, which aims at shrinking the tumor before it is surgically removed. If given after surgery, it is known as adjuvant chemotherapy, which focuses on killing the cancer cells left after the surgery. Sometimes, the chemo drugs are administered in combination with radiotherapy, biological therapy, or surgery. Side Effects: A Detailed View Chemotherapy is a systemic cancer treatment that can affect the entire body. The chemo drugs work by destroying rapidly-dividing cancer cells. But, these drugs are not able to differentiate between malignant cells and normal body cells. Malignant cells as well as some other normal cells like those in the blood, intestinal tract, nails, hair, mouth, and vagina are constantly dividing. The chemo drugs travel throughout the body and destroy normal healthy cells in the bone marrow, digestive tract, hair follicles, mouth, and reproductive system. Some of them affect the cells in the lungs, heart, bladder, kidneys as well as the nervous system. This can lead to many side effects. The severity of the side effects depends upon the type of drugs administered and the patient's overall health. They can be acute (short-term), chronic (long-term), or permanent. Some common side effects are constipation, diarrhea, nausea, vomiting, fatigue, hair loss, and certain blood-related symptoms such as anemia. Other side effects include intestinal problems, loss of appetite, weight loss, nerve and muscle problems, sore mouth, gums, and throat, dry and discolored skin, kidney and bladder irritation as well as sexuality and fertility issues. Hair loss Temporary hair loss (alopecia) is one of the depressing consequences of this therapy as it affects your appearance. Hair follicle cells are one of the rapidly dividing cells in the body. Since the chemo drugs cannot differentiate between these cells and malignant cells, they destroy healthy hair follicles cells, leading to hair loss. Nausea It is one of the most common side effects which is observed. It can lead to loss of appetite, constipation, and dehydration. Moderate to severe nausea can also cause vomiting. Diarrhea and constipation The cells in the intestinal lining are among the rapidly growing normal cells that are destroyed during chemotherapy, causing diarrhea. Diarrhea during cancer treatment is also due to anxiety, stress, malnutrition, or colon surgery. It can cause stomach pain and cramping, bloating, nausea, loss of appetite, and skin irritation. Some pain relievers and anticancer medications can cause constipation. These symptoms may also occur if your diet doesn't contain adequate amount of fibers or fluids. Allergic or hypersensitivity reaction Chemo drugs can lead to allergies or hypersensitivity reactions triggered by the immune system response. Anaphylaxis is a severe allergic reaction, which can cause low-blood pressure, shock, and even death. Major symptoms of allergic reactions are breathing difficulty, skin rashes, hives, flushing (redness of the face and neck), swelling of the eyelids, lips and tongue, and systemic reactions such as liver and kidney diseases. Skin problems Skin problems such as rashes, or dry, flaky, cracked, and itchy skin may occur. Fatigue Most cancer patients complain of tiredness, lack of energy, and fatigue. It is due to pain, loss of appetite, lack of sleep as well as low blood count. Fatigue appears suddenly and can last for several days, weeks, or months. Mouth and throat sores Anticancer drugs can cause irritation of the tissues of the mouth and throat, resulting in bleeding. They may also lead to tender gums and sore throat. Mouth sores, also known as stomatitis or mucositis, cause swollen, red ulcers in the oral cavity. The patient is unable to talk, eat, chew, or swallow due to painful ulcers. Nerve and muscle effects In some cases, anticancer drugs affect the nerves, leading to peripheral neuropathy. Therefore, the symptoms like weakness, burning, tingling, pain or numbness in the hands or feet can be experienced. Some drugs cause weakness or soreness of the muscles. Nerve and muscle-related problems can also lead to symptoms such as loss of balance, pain when walking, shaking or trembling, jaw pain, stomach pain, and hearing loss. Suppressed bone marrow Blood cells like white blood cells, red blood cells, and platelets are produced in the bone marrow. Since the therapy targets rapidly dividing cells, it affects the bone marrow cells. As a result, the production of blood cells in the bone marrow is suppressed, increasing the risk of infections. Anemia Reduced ability of bone marrow to produce red blood cells can cause a decrease in their number. Red blood cells are responsible for carrying oxygen to all parts of the body. Due to deficiency in red blood cells or anemia, body tissue is deprived of sufficient amount of oxygen. Anemia causes symptoms like fatigue, shortness of breath, dizziness, weakness, and tiredness. Infection Chemotherapy causes diminished production of white blood cells (leukopenia) in the bone marrow, leading to weakened-immune system, which makes your body more vulnerable to infections. Infections are mainly due to bacteria, fungi, viruses, and parasites. Some common areas of infection are mouth, throat, lungs, sinuses, skin, intestine, and genital tracts. Major signs and symptoms of infection are swelling, redness, and pus at the site of injury, mucus or pus in the saliva, cough, nasal drainage, sore throat, high fever, chills, and a burning sensation during micturition. Bleeding or clotting problems Due to suppressed bone marrow functioning, the number of platelets decreases. Platelets play a major role in the process of blood clotting, and thus, prevent bleeding. Reduced platelet count leads to symptoms like unexpected bruising, longer bleeding after minor cuts, nosebleeds or bleeding gums, vaginal bleeding other than menstruation, hematuria, black or bloody stool, headaches, and changes in vision. Flu-like symptoms Some people experience flu-like symptoms, a few hours after the chemo cycle. These symptoms include headache, nausea, tiredness, chills, slight fever, loss of appetite, and muscle and joint pain. Effect on sexual organs The therapy can affect sexual organs in both men and women. The anticancer drugs can lower the sperm count, which may result in temporary or permanent infertility in men. Anticancer drugs can affect the ovaries and hormonal levels. This can cause menopause-like symptoms (dry vagina and hot flashes), and temporary or permanent infertility in women. In spite of these side effects, chemotherapy is one of the most effective treatment options for various types of cancer. In most cases, the side effects disappear after the treatment is stopped. These effects can be prevented by taking appropriate medications, maintaining proper hygiene, intake of dietary supplements, and following a healthy lifestyle that includes a healthy diet and regular exercises. Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a replacement for expert medical advice.