Nausea and vomiting carries the worst memories of chemotherapy during cancer. However, the intensity of the discomfort differs in every individual. It is the most common question asked by many cancer patients that why does chemotherapy cause nausea and vomiting for something that is not even eaten? Scientists have traced down a vomiting center in the brain that is triggered by the infusion of chemotherapy drugs in our blood. Some people might feel nausea immediately after the drug administration and some may experience it a day later. All chemotherapy drugs could induce some nausea or vomiting like feeling, however different drugs have different emetogenic potential. Chemotherapy drugs for lymphoma are more likely to trigger nausea.

There are several factors that could stimulate the vomiting center in the brain and  cause nausea and vomiting,  these factors include the following:

1. Signals from chemoreceptor trigger zone (CTZ) in the brain that is stimulated by any chemical introduced in the blood
2. Brain cortex reacts to any sign of sight, smell, taste or emotional pain
3. Signals from the body balancing part of the ear might induce vomiting, this could even provoke motion sickness
4. Signs from the organs that are inflicted might evoke vomiting

These signals are transmitted through the neurotransmitters, chemicals that carry message within the nerves. The nausea and vomiting is most commonly brought about by activation of CTZ through various chemicals passed in the blood stream. Many people might vomit or feel nauseous by simply looking at  the drug or smelling a vomit during their previous cycles.

Antiemetics are the drugs given to combat or suppress the discomfort and uneasiness of nausea or vomiting. Some common antiemetics for chemotherapy are:

1. Prochlorperazine: Prochlorperazine is the most common drug for any kind of vomiting
2. Metoclopramide: Another common anti emetic is metoclopramide, it could be taken either as a pill or as an infusion along the veins
3. Dolasetron: Dolasetron belongs to a class of drugs called  serotonin antagonists or 5-HT3 receptor antagonists.  Serotonin antagonists help relieve chemotherapy induced nausea and vomiting and is also given to prevent it.

Few drugs complement or add to the efficacy of an antiemetic when given in combination with the above mentioned antiemetic drugs. Some  other drugs prescribed by the doctors to prevent and ease nausea and vomiting are:

1. Dexamethasone: These are the steroids that play a definitive role when given with an anti emetic drug
2. Aprepitant: This drug shows result when coupled with a 5-HT3 Antagonist. They have been proven to be effective  in suppressing the effect of highly emetogenic chemotherapy drugs

Many cancer patients pose a question as to why does chemotherapy cause nausea? Nausea is the most discomforting side reaction of chemotherapy medications. Doctors often administer some antiemetics or anti-sickness drugs to provide relief and prevent for nausea. Antiemetic drugs are usually administered in combinations. The effectiveness of these drugs vary and therefore some drugs last for a short time and need to be given more often while there are some that are effective enough for a longer duration.