Prophylaxis of nausea and vomiting is a critical part of medical care, especially around surgery and certain treatments, aimed at preventing these uncomfortable and sometimes distressing symptoms before they start.

Understanding Nausea and Vomiting

Nausea is an unpleasant feeling that makes you feel like you might need to throw up. It creates a queasy sensation in your throat or stomach, even if vomiting never actually happens. Vomiting, on the other hand, is when the contents of your stomach are forcefully expelled through your mouth. While these two experiences often occur together, they can also happen separately. A person can feel nauseated for hours without ever vomiting, or in some cases, vomiting can occur suddenly without any preceding nausea.^[11]

What makes nausea particularly challenging is that it involves multiple systems in the body working together in complex ways. Your digestive system, your senses of sight and smell, your emotions, memories from past experiences, nerve signals from various parts of your body, chemicals circulating in your blood, and even pressure changes in your brain can all trigger that uncomfortable feeling of nausea.^[11]

Epidemiology

When it comes to surgery and anesthesia, nausea and vomiting are among the most common complications that patients face. In the general population undergoing surgery, approximately 30% of people will experience postoperative nausea and vomiting, which refers to these symptoms occurring after a surgical procedure.^[1] However, this number can vary dramatically depending on individual risk factors and the type of surgery being performed.

For people who fall into high-risk categories or who undergo certain types of surgical procedures, the chance of experiencing postoperative nausea and vomiting can climb as high as 80%.^[1] These high-risk groups often include women, younger patients, those with a history of motion sickness, and people undergoing certain types of surgeries such as gynecological procedures. In fact, gynecological day surgery patients face particularly elevated risks due to the combination of their gender, age, the type of surgery, and the use of opioid pain medications.^[5]

Beyond the operating room, nausea and vomiting affect large numbers of people with serious chronic illnesses. Among patients with advanced cancer, between 6% and 68% experience nausea. In people with heart disease, the prevalence ranges from 17% to 48%. For those living with kidney disease, 30% to 43% deal with nausea, and among patients with AIDS, the rate falls between 43% and 49%.^[13]

Causes

The reasons why nausea and vomiting occur are numerous and often interconnected. In the context of surgery and anesthesia, several factors play important roles. The medications used during anesthesia itself can trigger these symptoms. The physical stress of surgery on the body creates changes that may lead to nausea. Pain, particularly severe pain, is another significant contributor. The use of opioid medications for pain relief after surgery is a major factor that increases the risk of both nausea and vomiting.^[1]

For patients undergoing cancer treatment, chemotherapy and radiation therapy are well-known causes of nausea and vomiting. Some cancer medications are more likely than others to cause these side effects. The body’s response to the cancer itself, even without treatment, can also trigger nausea.^[10]

Other medical causes include problems with the stomach and intestines, such as blockages or slow emptying. Increased pressure on the brain from conditions like fluid buildup can cause nausea. Anxiety and high levels of stress are emotional triggers that can bring on these symptoms. Even strong smells, certain foods, or memories of previous episodes of nausea can be enough to trigger the sensation again.^[11]

Risk Factors

Several factors make some people more likely than others to experience nausea and vomiting, particularly in the context of surgery. Being female is one of the most significant risk factors for postoperative nausea and vomiting. Women are generally more susceptible than men to developing these symptoms after surgery and anesthesia.^[1]

Age plays a role as well, with younger patients typically facing higher risks than older adults. However, when prescribing preventive medications for elderly patients over 70 years old, doctors often need to adjust doses downward because older people are more susceptible to side effects like low blood pressure and involuntary muscle movements.^[2]

A personal history matters greatly. People who have experienced motion sickness in the past, such as getting car sick or seasick, are more likely to develop nausea and vomiting after surgery. Similarly, individuals who have had postoperative nausea and vomiting after previous surgeries face increased risk during future procedures.^[1]

The type of surgery also influences risk. Certain procedures, particularly gynecological surgeries, carry higher chances of causing postoperative nausea and vomiting. The length and complexity of the surgery can also increase risk, with longer procedures generally posing greater challenges.^[5]

The use of opioid pain medications represents a major modifiable risk factor. While these drugs are effective for managing pain, they significantly increase the likelihood of experiencing nausea and vomiting. This creates a difficult situation where pain relief must be balanced against the risk of these uncomfortable side effects.^[2]

Symptoms and Their Impact

The experience of nausea itself is deeply unpleasant. People describe it as a queasy, uneasy feeling centered in the stomach or throat, often accompanied by a sensation that vomiting is about to occur. This feeling can be constant or come in waves. Some people also experience increased saliva production, sweating, dizziness, or a general sense of being unwell.^[11]

When vomiting occurs, it involves the forceful expulsion of stomach contents and is often preceded by retching, which is the rhythmic contraction of the respiratory muscles and stomach without actually bringing anything up. Vomiting can lead to additional problems such as dehydration, loss of important minerals and electrolytes from the body, and physical complications like wound problems if it occurs after surgery.^[2]

The impact on quality of life can be substantial. For patients recovering from surgery, nausea and vomiting can be extremely distressing and ranks high among their concerns about the procedure. These symptoms can significantly affect patient satisfaction with their care. They may also prolong the time a patient needs to spend in the recovery room after surgery and can increase the risk of needing to be readmitted to the hospital.^[1]

In serious cases, complications can develop. Repeated vomiting can cause wounds to open up, create imbalances in body chemistry, worsen pain, lead to dangerous dehydration, or even result in accidentally breathing stomach contents into the lungs, a condition called aspiration.^[2]

Prevention Strategies

Modern approaches to preventing nausea and vomiting have shifted significantly toward being proactive rather than reactive. Instead of waiting for symptoms to occur and then treating them, medical teams now focus heavily on identifying patients at risk and taking preventive steps before problems begin.^[1]

Risk Assessment

The first step in prevention involves careful assessment. Before surgery, anesthesiologists evaluate each patient’s individual risk factors for postoperative nausea and vomiting. They look at factors like gender, age, history of motion sickness or previous postoperative nausea and vomiting, the type of surgery planned, and whether opioid pain medications will likely be needed. This assessment helps determine which patients need preventive measures and how aggressive those measures should be.^[1]

Medication Prevention

Several types of medications can be given before, during, or immediately after surgery to prevent nausea and vomiting from occurring. These antiemetic drugs, which means medications that prevent or reduce nausea and vomiting, work through different mechanisms in the body.

One commonly used medication is ondansetron, which belongs to a class of drugs called 5-HT3 receptor antagonists. This medication is typically given as 4 milligrams either by mouth or through an intravenous line every 8 hours. However, doctors must use caution with this drug because it can cause constipation and, in rare cases, affect heart rhythm by prolonging something called the QT interval. People born with a condition called congenital long QT syndrome should avoid this medication.^[2]

Another option is dexamethasone, a steroid medication usually given as a single 4-milligram dose through an intravenous line or injection into a muscle. The way this medication prevents nausea and vomiting is not fully understood, and it is not officially licensed for this use, but it has proven effective in clinical practice. One unusual side effect that can occur is acute pain in the rectal area when it is given intravenously.^[2]

Cyclizine is an antihistamine that works on the brain’s vomiting center. It can be given by mouth, through an intravenous line, or by injection into a muscle at a dose of 50 milligrams every 8 hours. For elderly patients, the dose is reduced to 25 milligrams every 8 hours. This medication should be avoided in people with severe heart failure or a rare genetic condition called porphyria.^[2]

Prochlorperazine acts on an area of the brain called the chemoreceptor trigger zone by blocking dopamine receptors. It can be given as 3 to 6 milligrams through the cheek (buccal route) every 12 hours, or as a one-time injection into a muscle at 12.5 milligrams. Elderly patients should receive reduced doses due to increased susceptibility to side effects like low blood pressure and involuntary muscle movements called extrapyramidal effects, which can include muscle stiffness and abnormal movements.^[2]

Droperidol is another medication that works primarily on the chemoreceptor trigger zone. However, its use is restricted to specialist doctors called consultant anesthetists, and it is reserved for situations where other medications have not worked. Like ondansetron, it carries a risk of affecting heart rhythm.^[2]

Studies have shown that combining different types of antiemetic medications that work through different mechanisms can be more effective than using a single drug alone. For instance, one study found that combining droperidol or tropisetron with dexamethasone was more effective at preventing nausea and vomiting in the immediate recovery period after gynecological surgery performed with a newer anesthetic called remimazolam.^[5]

Non-Medication Prevention

Prevention isn’t only about medications. Several non-drug approaches can help reduce the risk of nausea and vomiting. Minimizing patient movement after surgery can help, as can ensuring that pain is well-controlled with adequate but not excessive use of pain medications. Making sure patients have good oxygen levels and normal blood pressure also helps prevent these symptoms.^[2]

When possible, reducing or avoiding opioid pain medications can make a significant difference. Healthcare teams may consider using alternative pain control methods or different classes of pain relievers that carry lower risks of causing nausea and vomiting. Simple pain medications and non-steroidal anti-inflammatory drugs can often be helpful additions to a pain management plan that reduces opioid dependence.^[2]

Dietary and Lifestyle Modifications

What and how a person eats can influence their experience with nausea and vomiting. For someone at risk, eating smaller, more frequent meals rather than three large meals a day can be helpful. It’s often better to drink liquids between meals rather than with meals. Foods that are bland and at room temperature or cooler tend to be better tolerated than hot, spicy, or heavily seasoned foods.^[4]

Simple home remedies can sometimes provide relief. Drinking beverages known to settle the stomach, such as ginger ale or chamomile tea, may help. Plain, easily digestible foods like crackers, plain rice, bananas, and toast are often recommended. Avoiding caffeine, which can worsen dehydration, is also advisable.^[4]

For people experiencing nausea, sucking on hard candy with pleasant flavors like lemon or mint can help mask unpleasant tastes and smells. Taking time to digest food properly by remaining upright and avoiding physical activity too soon after eating can prevent nausea from worsening. Even brushing teeth too soon after eating can sometimes trigger nausea, so it’s better to wait a while.^[16]

Pathophysiology

The body’s nausea and vomiting response involves complex interactions between several different pathways and systems. Understanding how these pathways work helps explain why different medications are used for prevention and treatment.

Four main pathways can trigger nausea and vomiting signals that ultimately reach the brain. The first is the chemoreceptor trigger zone, a specialized area in the brain that monitors the blood for toxins and certain chemicals. When it detects these substances, it sends signals that can cause nausea and vomiting. This is why many medications, including chemotherapy drugs and opioids, can trigger these symptoms through this pathway.^[13]

The second pathway involves the gastrointestinal tract itself. Nerves in the stomach and intestines can send signals when there are problems with digestion, such as slow emptying of the stomach, inflammation, or blockages. These signals travel to the brain and can trigger nausea and vomiting as a response.^[13]

The third pathway is the vestibular system, which is the balance system in the inner ear. When this system detects unusual motion or gets conflicting signals, as happens with motion sickness, it can trigger nausea and vomiting. This explains why people with a history of motion sickness are more susceptible to postoperative nausea and vomiting.^[13]

The fourth pathway involves the cerebral cortex, the thinking and processing part of the brain. Anxiety, fear, unpleasant memories, disturbing sights, and bad smells can all trigger nausea through this pathway. This is why stress management and creating a calm, pleasant environment can help reduce nausea.^[13]

When nausea occurs, the body also experiences changes beyond the stomach. Blood flow patterns shift, with less blood going to the stomach and more going to the intestines. The muscles in the stomach and intestines may stop their normal coordinated movements, slowing down or reversing the normal direction of digestion. Various stress hormones and chemical messengers are released into the bloodstream. All of these changes work together to create the uncomfortable sensation of nausea and, if severe enough, trigger the vomiting reflex.^[11]

In the surgical setting, the situation becomes more complex because multiple factors often work together. The anesthetic drugs affect the brain and chemoreceptor trigger zone. Surgery causes inflammation and releases chemicals into the bloodstream. Pain triggers stress responses. Opioid pain medications affect multiple pathways. The combination of these factors explains why postoperative nausea and vomiting is so common and why prevention requires a comprehensive, multi-pronged approach.^[1]

Generally, uncomplicated postoperative nausea and vomiting rarely lasts beyond 24 hours after surgery. However, when nausea and vomiting persist beyond this timeframe or become severe, it suggests that multiple factors may be involved and that more intensive treatment or investigation may be needed to identify and address the underlying causes.^[2]