Health Tips

Disgust is perhaps one of the strongest emotions of humankind, because rarely does an emotion trigger a biological response, i.e. nausea and vomiting.

But today, we’re going to discuss the literal nausea and vomiting — which you feel sick, unwell and want to throw up. It’s an extremely unpleasant feeling that most of us may experience once in a while.

What can trigger nausea and vomiting?

Nausea and vomiting can be caused by a wide range of reasons, here are just a few:

• Infection that involves the gastrointestinal systems and/or the brain, e.g. gastroenteritis, encephalopathy 

• Motion sickness

• Morning sickness/ pregnancy-related

• Side effects of certain medical treatments, such as chemotherapy for cancers and opioid-based painkillers (e.g. morphine, fentanyl)

• Migraine

• Vestibular neuritis

• Gastroparesis

• Gastritis

• Obstruction in gastrointestinal system

• Excess alcohol consumption (‘hangover’)

• Post-operation

Nausea and vomiting is a complex physiologic response that involves various parts of the brain, spinal cords and the stomach. 

Image credit: ClinicalGate

Antiemetics to the rescue

Prior to the emergence of modern medicine, people relied on herbal remedies to relieve nausea and vomiting, such as ginger, peppermint and aromatherapy. If your occasional nausea and vomiting can be relieved by these natural products, then good for you; but if they don’t, modern medicine has got your back.

Antiemetics are a group of medications used to treat nausea and vomiting (emetic means ‘causes vomiting’, so antiemetic means ‘stop vomiting’). There are a wide range of antiemetics available, they act on the ‘vomiting centre’ in the brain and/or receptors that trigger vomiting in the gastrointestinal system.

Common antiemetics

These are the antiemetics doctor commonly prescribed for minor complaints, such as occasional nausea and vomiting that is not alarming, related to pregnancy or to prevent motion sickness before one takes a plane. For examples:

• Metoclopramide, domperidone (Motilium®), prochlorperazine (Stemetil®), chlorpromazine (Largactil®), itopride (Ganaton®), Olanzapine (Zyprexa®)*— These medications fall under the category of dopamine antagonist. They reduce nausea and vomiting by blocking the dopamine type 2 (D2) receptor in the ‘vomiting centre’ of the brain as well as in the gastrointestinal tract (except domperidone, which acts on the D2 receptor in gastrointestinal tract only). 

• Promethazine (Phenergan®), Meclozine (Veloxin®, with added vitamin B6), Cinnarizine (Stugeron®)— These antiemetics belong to the first-generation antihistamine group. Similar to their second-generation counterpart (e.g. loratadine, cetirizine), they reduce skin itchiness and allergies; however, the first-generation anti-emetics has an extra function, which is to relieve nausea and vomiting. These are commonly used for pregnancy-related nausea and motion sickness because they generally have fewer side effects compared to dopamine antagonists mentioned above.

*Only certain countries’ clinical practice recognizes the use of olanzapine in treating nausea and vomiting. In Malaysia, olanzapine is primarily used as the treatment for schizophrenia and bipolar disorders. It is only available as a prescription medication from a psychiatrist specialist.

Chemotherapy-induced nausea and vomiting (CINV)

Can you imagine some nausea and vomiting get so serious that any of the antiemetics mentioned above might not work? That’s the case for a condition known as chemotherapy-induced nausea and vomiting (CINV).

Image credit: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/intravenous-chemotherapy

CINV refers to the nausea and vomiting caused by the side effects of chemotherapy among cancer patients. Such nausea and vomiting is way more serious, and would require different classes of antiemetics (and often more than one) to manage it. These antiemetics are less common than those we mentioned above because their utility remains in treating more severe forms of nausea and vomiting such as CINV.

• Granisetron (Kytril®), ondansetron, palonosetron (Akynzeo®, in combination with netupitant)— These antiemetics belong to the serotonin  (5-HT3 receptors) antagonist. Similar to the dopamine receptor we mentioned above, the 5-HT3 receptors are another group of receptors involved in the ‘vomiting centre’ of our brain and gastrointestinal tract. These medications block said receptors, leading to relief of nausea and vomiting.

• Aprepitant (Emend®), Netupitant (Akynzeo® capsule, in combination with palonosetron), Fosnetupitant (Akynzeo® injection, in combination with palonosetron)— These antiemetics are part of the neurokinin antagonist (NK-1) group. They inhibit Substance P, which is a compound with a cool-sounding name that activates the nausea and vomiting response.

• Dexamethasone — Dexamethasone is a corticosteroid that also possesses the ability to prevent nausea and vomiting, whilst reducing allergic reactions to chemotherapy.

• Lorazepam — Lorazepam is a benzodiazepine that is commonly used to treat anxiety and insomnia. It has an additional action on the ‘vomiting centre’ of the brain (blocking the dopamine), thus reducing nausea and vomiting.

These antiemetics can be given before or after chemotherapy to prevent or treat nausea and vomiting. Patients are encouraged to take antiemetics when they feel nauseous, not when they start vomiting to prevent them from vomiting out the antiemetics.

CINV can occur in ways that are different from nausea and vomiting of minor causes. They can be classified as:

1. Acute (occur within the first 24 hours of starting chemotherapy)

2. Delayed (occur 2 to 5 days after chemotherapy)

CINV can be triggered by seemingly unrelated stimuli. Certain odours, meeting the chemotherapy nurse in the grocery store or the journey to the chemotherapy clinic can elicit nausea even after treatment.

Chemotherapy drugs also have different emetogenic potential, i.e. the potential to cause nausea and vomiting. Chemotherapy drugs such as cisplatin and doxorubicin have a very high potential of causing nausea and vomiting. 

Image credit: 10.1056/NEJMra1515442

Health Minister Khairy Jamaluddin has officially acknowledged the use of medical marijuana in Malaysia, citing that marijuana and its by-products can be imported for medicinal use. One of the medical benefits of marijuana is treating nausea and vomiting. 

Side effects of antiemetics

Every medication comes with its fair share of side effects, and antiemetics are no exception. Depending on the class of antiemetics, they may come with various adverse effects:

• Promethazine (Phenergan®), Meclozine (Veloxin®, with added vitamin B6), Cinnarizine (Stugeron®)— They may cause drowsiness and sedation. Metoclopramide also causes sedation to some extent.

• Metoclopramide, prochlorperazine (Stemetil®), chlorpromazine (Largactil®), Olanzapine (Zyprexa®)— May cause extrapyramidal symptoms, which one may feel restless or tense (akathisia), involuntary muscle contraction (dystonia), symptoms similar to Parkinson’s disease and jerking movements in the face and tongue (tardive dyskinesia). The risk of this adverse effect is higher when they are administered through intravenous at high doses, or to elderly who already have Parkinson’s disease. It is also for this concern that their use is less preferred in pregnant women.

• Urinary retention, constipation, fast heartbeat, delirium, confusion (these are collectively known as cholinergic symptoms) can be caused by many of the dopamine antagonists and antihistamines.

• A heart problem called QT prolongation, which may be caused by ondansetron and granisetron.

Overall, they are safe if used according to the doctor’s instructions.

When nausea and vomiting get serious

Nausea and vomiting, if it gets too frequent, can become a medical emergency. 

In pregnant women, persistent nausea and vomiting is called hyperemesis gravidarum that requires immediate medical attention. You can even die from profuse nausea and vomiting, because it causes your body to lose too much fluids and electrolytes, causing hypovolemic shock.

For any nausea and vomiting accompanied with:

• >4 times in a day

• Fever

• Altered mental state/ confusion

• Abdominal pain

• Diarrhoea

• Nausea and vomiting in children and/or pregnant women

Visit the emergency department immediately.

A word from DOC2US

If you have any questions related to nausea and vomiting, you can consult our professional doctors and healthcare professionals on DOC2US. DOC2US is a mobile application that allows you to talk to a doctor or any healthcare professionals via text chat at any time and from anywhere. For better communication, you can even send our online doctor images or voice messages related to your medical inquiry.

Download DOC2US app on Apple App Store, Google Play Store and Huawei App Gallery; or use our web chat at https://web.doc2us.com/

Note: DOC2US is not for medical emergencies. In the event of urgent medical conditions, please call 999.

Disclaimer: As a service to our users and general public, DOC2US provides health education contents. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Specific references have been linked in its relevant part of the article. 

Cover image credit: https://mellowed.com/stress-nausea-vomiting/

Written by

Ms Joyce Toh