Chemotherapy and Anti-Nausea Medications (Antiemetics)

When going through chemotherapy, nausea and vomiting are typically part of the process. As a result, many oncologists will prescribe anti-nausea medications, or antiemetics, as a preemptive measure for managing nausea induced by the chemotherapy. These medications are often prescribed in one of three ways: on a schedule, as needed (PRN), or a combination of both.

When going through my chemotherapy treatments, I was on several medications for nausea and all were on a schedule, with the exception of one that was PRN. I received two different forms of antiemetics: pills I took on a daily basis and IV treatments I received in combination with my actual chemotherapy (or in separate treatment days as needed). There are a number of anti-nausea medications available today. I was prescribed Zofran (ondansetron), Reglan (metoclopramide), Phenergan, (promethazine), Ativan (lorazepam), and Marinol (dronabinol). These were in pill form. I also received Aloxi (palonosetron), Decadron (dexamethasone), and Emend (aprepitant) via IV on the days I received chemotherapy and on additional days when the nausea was especially bad.  

The Zofran and Aloxi were 5-HT3 receptor antagonists, which work in the gastrointestinal tract central nervous system by blocking serotonin receptors. Common side effects of this medication category include fatigue, diarrhea, constipation, and dry mouth. The reason diarrhea and constipation are both possible side effects are that everyone’s biochemistry is different and each body reacts to the medication differently. Because these medications work directly in the digestive tract, they can cause either reaction within the digestive tract or no reaction at all.  



Reglan is a dopamine antagonist and works in the gastrointestinal tractas a pro-kinetic and brain to treat nausea and vomiting. Side effects with Reglan included fatigue, drowsiness, constipation, restlessness, and dizziness.

Phenergan is categorized as an antihistamine or H1 histamine receptor antagonist. It can be administered as a pill or rectal suppository. Common side effects include fatigue, dizziness, drowsiness, dry mouth, irritability, constipation, tardive dyskinesia (involuntary and repetitive body movements), paresthesia (numbness, tingling, tickling, or burning sensation of the skin with no long-term physical effect – also known as the feeling of “falling asleep” or “pins and needles”), and akathisia (restlessness).

Ativan is classified as a benzodiazepine. Benzodiazepines are effective in treating nausea when used in combination with drugs like Compazine and Zofran. These drugs are safe for short term use, though long term use can cause dependency. Side effects of benzodiazepines include sedation, dizziness, drowsiness, reduced alertness, impaired concentration, and loss of coordination.

Decadron is a steroid. It is given in low doses to treat nausea, although how it works is unknown. Side effects of Decadron include increased appetite, suppressed immune system, irritability, mood swings, muscle atrophy, hypertension, night sweats, and elevated liver enzymes.

Emend is the only NK1 receptor antagonist commercially available at this time. Its discovery was a turning point in the treatment of chemotherapy caused nausea and vomiting.  NK1 receptor antagonists not only treat immediate nausea and vomiting, they are also effective at treating delayed phases of emesis. Common side effects include diarrhea or constipation, appetite loss, headache, insomnia, fatigue, dizziness, hiccups, hair loss, mild skin rash, and a ringing in the ears.

Marinol is a cannabinoid. The active ingredient is a synthetic form of tetrahydrocannabinol (THC), the same chemical that is in marijuana. It is a Schedule III narcotic drug in the U.S. but is legal in every state with a valid prescription. Common side effects include loss of coordination, changes in perception, increased appetite, dizziness, and a sense of feeling “high.” 

These are just a few of the most commonly prescribed anti-nausea medications used today for cancer chemotherapy patients. Why so many anti-nausea meds? Simply because they all work on the body in different ways and through different systems in the body. It is very difficult to pinpoint which particular system within the body is reacting and causing the nausea. Having an array of medications that work in different ways covers all the bases – and even with so many medications, there were still days that the nausea was so bad I had to go in to get the IV treatments, or days that I couldn’t get out of bed because I felt so sick. Fortunately, I didn’t have a problem with vomiting, just nausea.