Several medicines can help with vomiting, and the best choice depends on what’s causing it. For a common stomach bug, an over-the-counter option like bismuth subsalicylate (the active ingredient in Pepto-Bismol) can ease nausea and upset stomach. For more persistent or severe vomiting, prescription medications like ondansetron are highly effective. Here’s what works for different situations.
Over-the-Counter Options
Bismuth subsalicylate is the most widely available OTC medicine for nausea and vomiting in adults and teenagers. It comes as chewable tablets, liquid, and capsules. It works best for vomiting tied to general stomach upset, indigestion, or mild food-related illness. One important restriction: children and teenagers who have or are recovering from the flu or chickenpox should not take it, because it carries a risk of Reye’s syndrome, a rare but serious condition.
Antihistamine-based medicines like dimenhydrinate (Dramamine) and meclizine (Bonine) are also available without a prescription. These are primarily designed for motion sickness but can help with other types of nausea as well. They tend to cause drowsiness, which is worth knowing if you need to stay alert.
Prescription Medicines for Severe Vomiting
When OTC options aren’t enough, doctors have several prescription tools. Ondansetron (Zofran) is one of the most commonly prescribed antiemetics. It blocks serotonin receptors that trigger the vomiting reflex, and it’s used for post-surgical nausea, chemotherapy-related vomiting, and sometimes severe stomach illness. Its most common side effects are headache, constipation, and fatigue.
Other prescription options include promethazine (Phenergan), which works as both an antihistamine and a sedative, and metoclopramide (Reglan), which helps the stomach empty faster in addition to reducing nausea. For chemotherapy patients who don’t respond to first-line treatments, synthetic cannabinoid medications like dronabinol and nabilone are sometimes prescribed.
How These Medicines Work
Your brain has a dedicated area for detecting toxins in the bloodstream, located at the base of the brain near the brainstem. This area sits outside the normal blood-brain barrier, which means it’s especially good at sensing chemicals that shouldn’t be there. It monitors five key chemical signals: serotonin, dopamine, histamine, acetylcholine, and a compound called substance P. Different anti-vomiting medicines block different signals, which is why certain drugs work better for certain causes. Motion sickness, for example, involves histamine and acetylcholine pathways, while chemotherapy-induced vomiting heavily involves serotonin.
Motion Sickness
Motion sickness medicines work best when taken before symptoms start. Once vomiting begins, the stomach slows down and may not absorb oral medication properly. If you know you’ll be in a car, on a boat, or flying, take your medicine at least one to two hours beforehand.
For short trips of six hours or less, meclizine or dimenhydrinate are the standard recommendations. Meclizine lasts 8 to 24 hours depending on the form, and dimenhydrinate lasts about 8 hours. For longer exposures, like a multi-day cruise or rough seas, a scopolamine patch is more practical. It takes 6 to 8 hours to reach full effect but then works continuously for up to 72 hours. Promethazine is reserved for intense motion exposure and lasts about 15 hours per dose, though it causes significant drowsiness.
For children ages 6 to 12, dimenhydrinate (sold as Dramamine for Kids in chewable form) is the go-to option at a lower dose of 12 to 25 mg, given one to two hours before travel. Scopolamine patches should be avoided in children entirely, as they can cause hallucinations and confusion.
Pregnancy-Related Nausea
The combination of doxylamine (an antihistamine) and vitamin B6 is the recommended first-line treatment for nausea and vomiting during pregnancy. Ginger also has solid clinical support. A large review of alternative therapies found that ginger, either alone or combined with vitamin B6, had the greatest effect on reducing nausea of all the non-pharmaceutical options studied, with moderate-quality evidence supporting it. The typical recommended dose is 250 mg of standardized ginger extract taken three to four times daily, up to 1,000 mg per day total.
Vomiting in Children
For children with vomiting from a stomach bug, ondansetron has the strongest evidence of any medication. A large meta-analysis published in Pediatrics found that ondansetron was the only antiemetic that reduced the number of vomiting episodes, decreased the need for IV fluids, and stopped vomiting more effectively than placebo. The same review found that dimenhydrinate actually performed worse than placebo when side effects were factored in, so it’s not a great choice for stomach illness in kids despite being available over the counter.
Bismuth subsalicylate products should be avoided in children, particularly those with viral illnesses, due to the Reye’s syndrome risk. If a child under 2 has been vomiting for more than 12 hours, or a child under 12 has been vomiting for more than 24 hours, that warrants a call to their doctor.
When Vomiting Needs Urgent Attention
Most vomiting resolves on its own or responds to medication, but certain signs mean it’s time to seek immediate care. Vomit that contains blood, looks like coffee grounds, or appears green signals a potentially serious problem. Signs of dehydration also warrant urgent attention: excessive thirst, dark urine, urinating very infrequently, dry mouth, or feeling dizzy when you stand up. For adults, vomiting that continues beyond two days without improvement should be evaluated by a doctor, even if you’re keeping some fluids down.