What Are Medication Side Effects That Cause Vomiting?

Many medicines can cause nausea (an unsettled feeling in the stomach) or vomiting, especially some antibiotics, opioid pain medicines, anti-inflammatory pain relievers, and cancer treatments. These effects may begin after starting a medicine, changing its dose, or taking it with other drugs. Vomiting can also have causes unrelated to medicine, so note when it happens and ask a pharmacist or clinician to review your medicines.

Which medications can cause nausea and vomiting?

Vomiting is a possible side effect of several prescription and over-the-counter medicines. The likelihood depends on the specific drug, its dose, other medicines being taken, and individual health factors. Some medicines mainly cause nausea, while others can cause both nausea and vomiting.

• Antibiotics: Some antibiotics can cause an upset stomach, nausea, and diarrhea. These effects are often temporary, but persistent vomiting should be discussed with the prescribing clinician. The NHS guidance on antibiotic side effects also explains that antibiotics can occasionally cause allergic reactions, which may involve wheezing, throat tightness, or swelling of the face or mouth.

• Anti-inflammatory pain relievers: Medicines such as ibuprofen, naproxen, and aspirin can cause stomach discomfort and nausea. Taking more than the recommended amount of these medicines can increase the risk of stomach problems, including ulcers. MedlinePlus information on pain relievers explains these risks and the importance of using pain medicines as directed.

• Opioid pain medicines: Prescription medicines such as oxycodone, hydrocodone, fentanyl, and tramadol can cause nausea and other digestive side effects. MedlinePlus information on opioids also identifies slowed breathing and reduced alertness as serious warning signs of an overdose, which requires emergency help.

• Cancer treatments: Chemotherapy can cause nausea and vomiting, and some targeted therapies and immunotherapy medicines can also produce these effects. Medicines used during anesthesia and pain medicines given after surgery may contribute as well. According to the National Cancer Institute, medicines that prevent or reduce nausea and vomiting are available for people receiving cancer treatment.

• Other prescription and over-the-counter medicines: Many additional medicines can list nausea or vomiting among their possible side effects. Vitamins, dietary supplements, and combinations of medicines can also affect how a person responds to treatment. The specific product information is the best starting point for identifying whether a particular medicine is known to cause these symptoms.

Why can a medicine suddenly start causing vomiting?

Vomiting may begin when a person first starts a medicine, after the dose changes, or following a change in other medicines or supplements. A medicine that was previously tolerated may also cause new symptoms when health circumstances change. The US Food and Drug Administration (FDA) explains that side effects can be affected by age, other drugs or supplements, and underlying health conditions.

The way a medicine is taken can also matter. Some medicines should be taken with food to reduce stomach discomfort, while others have specific instructions about meals. Following the directions on the prescription label or patient information leaflet is important; taking a medicine with food is not appropriate for every drug.

Vomiting that starts soon after a new medicine is introduced may be related to that medicine, but timing alone cannot establish the cause. An infection, another health problem, or an interaction between treatments may also explain the symptoms. A clinician or pharmacist can review the timing, dose, other medicines, and relevant medical history.

What should you do if a medication causes vomiting?

If you suspect that a medicine is causing vomiting, contact the prescribing clinician or a pharmacist for advice, particularly if the symptom recurs or interferes with taking the medicine. Do not independently reduce the dose, stop an essential prescription, or change the schedule unless you have been given instructions for doing so. Depending on the medicine and the symptoms, a clinician may recommend a different way of taking it, a dose adjustment, or an alternative treatment.

While arranging advice, consider these practical steps:

• Check the medicine label for instructions about food, timing, missed doses, and possible side effects.
• Take small, frequent sips of water or another suitable clear fluid if you can keep liquids down.
• Write down the medicine name, dose, time taken, and when the nausea or vomiting began.
• Keep a list of other prescription medicines, over-the-counter products, vitamins, and supplements you use.
• If you vomit after taking a dose, ask a pharmacist or clinician whether you need further instructions before taking another dose. Do not automatically repeat it, because the correct advice depends on the medicine and timing.
• Check with a healthcare professional before taking an additional medicine to control vomiting, because it may not be suitable for every person or medication combination.

Following this approach can help the healthcare professional decide whether the suspected side effect requires a change in treatment or further evaluation. The FDA recommends discussing possible dose adjustments or alternative medicines with a healthcare professional rather than making those changes independently.

When does vomiting after taking medication require urgent medical attention?

Occasional nausea may be manageable, but repeated vomiting can lead to dehydration and may prevent an important medicine from being absorbed properly. Seek prompt medical advice if vomiting continues, worsens, prevents you from keeping fluids down, or makes it difficult to take essential medicines. Advice should be sought sooner for infants, older adults, and people whose medical conditions increase their risk from dehydration.

Seek emergency medical care if vomiting occurs with concerning symptoms such as the following:

• Blood in the vomit or vomit that looks like coffee grounds.
• Sudden or severe abdominal pain, confusion, fainting, or markedly reduced alertness.
• Difficulty breathing or swelling of the lips, tongue, mouth, or throat, particularly after taking a medicine.
• Signs of a possible opioid overdose, including unusually slow or shallow breathing, inability to wake up, or extreme drowsiness.
• Persistent vomiting with signs of significant dehydration, such as very little urine, dizziness, or inability to keep fluids down.

The NHS guidance on vomiting identifies blood in the vomit, severe abdominal pain, confusion, and certain other warning signs as reasons to seek urgent or emergency care. Suspected medication overdose or a severe allergic reaction also requires immediate attention. Do not wait for the symptoms to resolve on their own when these warning signs occur.

How can a clinician determine whether a medicine is responsible?

A healthcare professional will usually review when the vomiting began in relation to each medicine, whether a dose or treatment recently changed, and whether other symptoms appeared. They may also ask about recent illnesses, food intake, medical conditions, and the use of nonprescription products or supplements. An examination or additional tests may be needed when the symptoms suggest another cause or a complication.

Bring the medication packaging or an up-to-date medicine list to the appointment when possible. Include the dose and timing of each medicine, how often vomiting occurs, and whether fluids and food stay down. This information can help the clinician assess the likely cause and decide whether treatment needs to be adjusted.

Medication-related vomiting is not always a reason to stop treatment. The safest next step depends on the medicine involved, the reason it was prescribed, and the effect the symptoms are having on your ability to take it safely.