The gastroenteritis, often accompanied by nausea and vomiting, can be a real challenge to manage. Fortunately, the use of antiemetics (also known as antinauseants) such as dimenhydrinate can help control these symptoms.  These effective and generally well-tolerated medications are specifically designed to prevent and treat nausea and vomiting, thus improving the comfort of the sufferer. However, it is important to note that each individual may react differently, and certain side effects may occur.

Understanding nausea and vomiting

Causes of nausea and vomiting

Nausea and vomiting can be caused by a multitude of factors. Digestive disorders, such as gastroenteritis or gastroesophageal reflux disease, are among the most common causes. Neurological conditions such as migraines or head trauma can also cause these symptoms.

Other causes include motion sickness, certain infections, liver disease, kidney disease, ENT disease, heart disease and side effects of medications, for example certain antidepressants, painkillers or cancer treatments.

It's important to note that nausea and vomiting can also be symptoms of more serious problems, such as intestinal obstructions, and should be assessed by a healthcare professional if they persist.

The role of the digestive system

The digestive system plays a central role in the mechanisms associated with nausea and vomiting. When irritation or inflammation occurs, as in gastroenteritis, the digestive system responds by causing contractions of the stomach and intestinal tract. These contractions can lead to nausea and vomiting.

• The central nervous system, notably the chemoreceptor trigger zone (CTZ), also plays an important role. The CTZ detects toxins in the blood and triggers a vomiting response to eliminate these harmful substances.
• In gastroenteritis, the digestive system is affected by inflammation, usually caused by a virus, bacteria or parasite. This inflammation can disrupt the normal functioning of the digestive system, leading to nausea and vomiting.
• What's more, the vomiting reflex involves a reverse peristaltic movement (contraction of the digestive tract), allowing stomach contents to rise through the esophagus, a function usually prevented by the lower esophageal sphincter.

Aggravating factors

A variety of factors can aggravate nausea and vomiting. These aggravating factors include:

• Medical treatments: Certain therapies, such as chemotherapy or radiotherapy, can intensify these symptoms.
• Pre-existing medical conditions: Conditions such as gastroparesis, intestinal distension or vascular occlusion can also increase the severity of nausea and vomiting.
• Ingestion of certain substances: Opiates, drugs commonly used for pain management, can cause or aggravate these symptoms.
• Psychological factors: Stress and anxiety can also play a role in the intensity of nausea and vomiting.

It is therefore crucial to take these factors into account when managing nausea and vomiting, including in cases of gastroenteritis.

What are antiemetics?

How antiemetics work

Antiemetics help regulate the nausea response by acting on the vomiting center in the brain. They can block the action of various neurotransmitters that stimulate this center, such as dopamine and serotonin. Some antiemetics work by blocking dopamine D2 receptors both centrally (in the brain) and peripherally (in the body).

Most antiemetics are antagonists of excitatory neurotransmitter receptors in the vomiting center, meaning they prevent activation of these receptors. Depending on their ability to cross the blood-brain barrier, i.e. to reach the brain, they may have a peripheral and/or central action.

• Peripheral action (in the body): they block emetogenic signals (vomiting signals) before they reach the vomiting center in the brain.
• Central action (in the brain): they block signals directly in the brain's vomiting center.

These drugs can also regulate esophageal contractions (contractions of the esophagus) and increase the tone of the gastroesophageal sphincter, which helps prevent acid reflux.

The different types of antiemetics

There are several types of antiemetics, each with a specific mechanism of action. Your pharmacist sees these different classes of antiemetics regularly, according to the prescriptions written and the needs of his patients. The main classes are :

• Antihistamines: These drugs are often used to prevent and treat nausea and vomiting, including those associated with motion sickness. Dimenhydrinate is a commonly prescribed antihistamine for nausea and vomiting.
• Antidopaminergics: block receptors for dopamine, a neurotransmitter that stimulates the vomiting center. Metoclopramide and domperidone are two commonly prescribed anti-dopaminergics.
• 5-HT3 antagonists: block receptors for serotonin, another excitatory neurotransmitter in the vomiting center. An example of a 5-HT3 antagonist is ondansetron.
• NK1 antagonists: block substance P receptors, which play a role in triggering vomiting. These drugs are often used for nausea and vomiting in people undergoing cancer treatment.
• Anticholinergics: inhibit the action of acetylcholine, a neurotransmitter that increases intestinal motility.

Each type of antiemetic is used according to the cause of nausea and vomiting, the severity of symptoms, and the patient's general state of health.

How to choose an antiemetic?

There are several factors to consider when choosing an antiemetic. First, the cause of the nausea and vomiting must be identified. For example, an antiemetic designed to relieve nausea due to chemotherapy will not necessarily be the same as one used for gastroenteritis. Secondly, the patient's age and general state of health are important. Some antiemetics may have particular side effects or contraindications in children, the elderly or people suffering from certain illnesses. The severity of symptoms and the presence of aggravating factors must also be taken into account. Finally, the patient's tolerance to the chosen antiemetic and possible side effects must also be considered.

Choosing an antiemetic on your own can be difficult, especially as most of them are only available by prescription. Your pharmacist is well placed to guide you and can, under consultation and according to his or her judgment, advise you or prescribe an antinauseant based on your symptoms, your health condition and the medications you are taking. Don't hesitate to ask for a consultation, which can also be by telephone, in the event of nausea or vomiting.

Use of antiemetics in children

Gastroenteritis in children: a frequent cause of vomiting

Gastroenteritis in children is a common condition that often leads to vomiting. It's usually caused by a viral infection, such as rotavirus or norovirus. Symptoms include vomiting, diarrhea, abdominal pain and sometimes fever.

In some cases, gastroenteritis can lead to dehydration, especially if the child vomits frequently and is unable to retain fluids. It is therefore essential to ensure that the child is rehydrated, and to watch for signs of dehydration such as dry mouth, absence of tears, increased thirst or decreased frequency of urination.

If symptoms worsen or persist, we recommend consulting a healthcare professional.

Choosing the right antiemetic for children

Antiemetics (antinauseants) should be used with caution in children. Dimenhydrinate , also known as Gravol(TM), is the drug most often used to control nausea and vomiting. It's important to note that it can cause drowsiness, and that the dose varies according to weight. Your pharmacist is a good resource for advice on the use of an antinauseant for your child, and for calculating the optimal dose.

Precautions for use and side effects in children

Antiemetics are generally effective and well-tolerated in children. However, like all medications, they can have side effects. Among the most common are drowsiness, fatigue, and digestive disorders such as constipation or diarrhea.

Some drugs, such as metoclopramide, can also cause extrapyramidal symptoms (involuntary body movements), particularly in children. Ondansetron, sometimes used to treat gastroenteritis, may cause a side effect of diarrhea or transient constipation.

It is essential to monitor these effects and inform the treating physician if necessary. In addition, antiemetics should be used with caution in children with certain medical conditions, such as cardiac or neurological disorders, because of the risk of potentially more serious adverse effects. It is therefore important to always consult a healthcare professional before starting antiemetic treatment in children.

Drugs used to treat nausea and vomiting

Dimenhydrinate: an antihistamine effective against nausea

Dimenhydrinate, also known by the trade name Gravol, is an antihistamine used to prevent and relieve nausea and vomiting.

This antiemetic acts by blocking the action of histamine, a chemical produced by the body, on H1 receptors. These receptors are involved in regulating the vestibular system, which plays a key role in controlling balance and coordinating movement.

Dimenhydrinate is effective against nausea and vomiting induced by various disorders such as chemotherapy, radiotherapy, motion sickness and digestive disorders such as gastroenteritis.

Despite its effectiveness, its use must be moderate, as it can induce side effects such as drowsiness. For long-term use, it's best to discuss it with a healthcare professional.

Ondansetron: a powerful antiemetic

Ondansetron is generally very effective against nausea by blocking the receptors for serotonin, a neurotransmitter that stimulates the brain's vomiting center. Ondansetron is frequently used, among other things, to prevent chemotherapy- and radiotherapy-induced nausea and vomiting. However, its use is not limited to these contexts. Ondansetron can also be effective against nausea and vomiting associated with gastroenteritis. Ondansetron is available by prescription only.

Metoclopramide: an antiemetic that affects intestinal transit

Metoclopramide is a prescription anti-emetic medication, notably prescribed to treat nausea and vomiting. It works by blocking dopamine D2 receptors, a neurotransmitter that stimulates the vomiting center. In addition, metoclopramide can promote intestinal transit by improving emptying from the stomach into the intestine.

Are over-the-counter mineral-based antacids (e.g. Gaviscon) effective against nausea?

Mineral-based over-the-counter antacids, such as Gaviscon, are mainly used to treat heartburn and acid reflux. They act as a gastric dressing that forms a protective barrier over the contents in the stomach, neutralizing excess acid.

Although this drug is not specifically indicated for the treatment of nausea, its action on gastric symptoms, such as gastro-oesophageal reflux, could potentially help relieve nausea if associated with this type of disorder. However, it is crucial to note that its efficacy as an antiemetic, i.e. antinauseant, has not been clearly established.

Your pharmacist is there to guide you towards the best possible treatment based on your symptoms, your health condition and the medications you are taking. Following a consultation, he can prescribe an antiemetic if he deems it appropriate, choosing the most appropriate molecule for you. Don't hesitate to consult him if you experience nausea or vomiting.

Natural antiemetics for gastroenteritis

Natural antiemetics

There is some evidence that certain natural remedies can help relieve nausea and vomiting. The one with the most data currently available concerning its anti-nausea properties is ginger.

• Ginger: renowned for its antiemetic properties, ginger can be taken as an herbal tea or as chewable or swallowable tablets, available from chemists.

Other plants traditionally attributed with anti-nausea properties include peppermint and chamomile. However, there is too little scientific evidence to support these potential properties for these plants to be frequently recommended by health professionals.

It's advisable to consult a health professional before using natural remedies to make sure they're safe and appropriate for your situation.

Effectiveness and limitations of natural antiemetics

Natural antiemetics can be an interesting alternative to conventional medicines. Used for centuries in traditional medicine, they are generally well tolerated and have few side effects. However, their effectiveness varies from person to person, and often depends on the cause of nausea and vomiting. Scientific studies to date on their efficacy are still limited and sometimes contradictory.

They should only be used in conjunction with appropriate medical treatment, and after consulting a healthcare professional. Indeed, some of them may interact with medications or be unsuitable for certain people, such as pregnant women or those suffering from certain chronic illnesses. What's more, prolonged use without medical advice can sometimes cause undesirable side effects.

Non-pharmacological measures to prevent and treat nausea and vomiting in gastroenteritis

Dietary advice for gastroenteritis

In the event of gastroenteritis, diet must be adapted to minimize nausea and vomiting, and promote recovery. Here are a few tips for proper nutrition:

• It's important not to stop eating. Eating allows the intestines to heal while regaining strength. Start with small amounts of food and gradually increase according to tolerance and appetite.
• Choose a light, easily digestible diet. Foods such as unsweetened cereals, bread, eggs and fish cooked in little fat are generally well tolerated.
• in its juice (not syrup) is recommended. They are rich in vitamins and minerals essential for recovery.
• Cooked vegetables are also a good option. They're easy to digest and provide important nutrients.
• If you tolerate dairy products well, or if they are lactose-free, you can eat low-fat yogurt and cheese.
• Water, herbal teas, broth and fruit juices (in small sips throughout the day) are essential to prevent dehydration, in addition to rehydration solutions. Avoid carbonated and alcoholic beverages, which can aggravate the problem.

We recommend eating small quantities, and avoiding fatty, spicy or sweet foods, which can aggravate symptoms.

The importance of hydration

Hydration is crucial during gastroenteritis, as the body can lose a lot of water and mineral salts essential for proper functioning. Dehydration can occur rapidly, especially in children and the elderly.

To stay hydrated, we recommend drinking water and oral rehydration solutions on a regular basis. These solutions contain balanced proportions of sodium, potassium, chloride, sugar and fluid, promoting effective recovery.

During treatment with antiemetics, hydration remains an essential pillar of recovery. In fact, hydration not only helps compensate for fluid losses due to vomiting, but also reduces nausea.

All in all, good hydration is essential to keep the body functioning properly and facilitate recovery from gastroenteritis.

Probiotics for gastroenteritis

Probiotics, live microorganisms, have demonstrated potentially beneficial effects in some studies for the treatment of diarrhea associated with gastroenteritis. They can help restore the balance of intestinal flora, which is disturbed during gastrointestinal infection, and may help reduce the duration of diarrhea.

The effectiveness of probiotics for a given problem varies according to the strain contained in the product, as not all strains have been studied for the same indication. Your pharmacist can help you choose the right probiotic for your particular problem, and advise you on the efficacy data available and dosage to follow, should you decide to start taking one.

When should you see a doctor?

In the event of gastroenteritis, it is crucial to monitor the evolution of symptoms. We recommend consulting a health care professional if :

• You or your child have severe symptoms such as intense vomiting, diarrhea lasting more than 3 days or constant acute abdominal pain.
• You may notice signs of dehydration such as a dry mouth, absence of urine for more than 12 hours or general weakness.
• You notice changes in the stool or vomit, such as the presence of blood or a black color.

Consultation with a doctor is also necessary if symptoms do not improve despite taking antiemetics.