Compare Zofran vs. Phenergan

Head-to-head comparisons of medication uses, side effects, ratings, and more.

Zofran
(ondansetron)

Phenergan
(promethazine)

Helps you feel less queasy. Zofran (Ondansetron) works well to prevent nausea and vomiting, and it's available in different forms that you don't have to swallow.Helps you feel less queasy. Phenergan (Promethazine) is used to treat and prevent nausea and vomiting from surgery, motion sickness, or pregnancy. While it's cheap and available in different forms to make it easier to take, it can make you feel very sleepy, and its side effects mean that children under 2 and adults over 65 shouldn't take it.
Reviews & ratings
Filter group. All currently selected
Filter group. All currently selected
4.91Zofran
Reviews for Zofran
66%
of people (All ages) say Zofran is worth it
51%
say it works well
15%
say it's a big hassle
366 reviews
Have you used Zofran (ondansetron)?
Worth itNot sureNot worth it
Reviews for Phenergan
82%
-16% worse vs. Zofran
76%
-25% worse vs. Zofran
5%
-10% worse vs. Zofran
Have you used Phenergan (promethazine)?
Worth itNot sureNot worth it
Side effects
ZofranPhenergan
  • Headache 2%
  • Constipation 11%
  • Fever 5%
  • Increased ast and alt 5%
  • Drowsiness 4%
  • Itching 2%
  • Tingling sensation 2%
More Zofran side effects »

The Phenergan FDA package insert doesn’t have numbers about how common side effects are.

More about Phenergan side effects »
How it works
ZofranPhenergan
Zofran (Ondansetron) is an antiemetic (anti-nausea medicine). It works by blocking the nerves that cause your nausea and vomiting reflex.Phenergan (Promethazine) is an antihistamine, which helps control allergies. It also seems to block your body's natural reflex for vomiting, which makes it useful as an antiemetic (anti-nausea medicine).
Type of medication
ZofranPhenergan
Prescription onlyPrescription only
Available as
ZofranPhenergan
  • Pill
  • Dissolving tablet
  • Liquid
  • Sublingual film
  • Pill
  • Liquid
  • Suppository
Used for
ZofranPhenergan
Risk factors for serious side effects
ZofranPhenergan
  • Long QT syndrome
Detailed Zofran (ondansetron) risks & warnings »
  • Children under 2 years of age
  • History of seizures
  • Age over 65
Detailed Phenergan (promethazine) risks & warnings »
Pregnancy

Research studies with animals haven’t found a risk to unborn babies, but it hasn’t been properly studied in humans.

Research studies with animals found harmful effects on unborn babies. It hasn’t been properly studied in humans. The benefits might outweigh the risks even if you’re pregnant. Talk with your doctor.

Interactions
ZofranPhenergan
  • Can interact with antidepressants.
No interactions related info.
Alcohol
ZofranPhenergan
No alcohol related info.
  • Don't drink alcohol to avoid intense side effects.
Pain
ZofranPhenergan
No pain related info.
  • Taking certain medications for pain, allergies, or mood conditions can worsen the side effects of Promethazine.
Sleep
ZofranPhenergan
No sleep related info.
  • You'll likely feel very sleepy, sluggish, or less alert after taking Promethazine. Avoid driving or other tasks that require your focused attention; be safe.
  • Can make you feel very sleepy, especially if you're taking other drugs that can make you sleepy or if you drink alcohol.
Upsides and benefits
ZofranPhenergan
  • Available in generic.
  • Available in forms that you don't have to swallow (like a tablet or film that dissolves in your mouth) if you're having trouble keeping anything down.
  • Starts working fast (in 30 minutes.
  • Available in generic.
  • Available as a syrup or tablet that you can take by mouth, or as a rectal suppository if you're unable to take anything by mouth.
Downsides and risks
ZofranPhenergan
  • Can cause headaches.
  • Can interact with antidepressants.
  • Can only be used to prevent nausea and vomiting, not to treat if it's already happening.
  • Can make you feel very sleepy, especially if you're taking other drugs that can make you sleepy or if you drink alcohol.
  • Can't be used in children under 2 years of age or if you're over 65 because of increased risk from side effects.
  • Can make your skin more sensitive to the sun.
Tips from our pharmacists for people taking the medication
ZofranPhenergan
  • If you're using the disintegrating tablet, make sure your hands are dry first, peel off the foil and remove the tablet. Place the tablet on the tongue to let it dissolve naturally, then swallow. Don't drink water or anything else.
  • Can cause headache, fatigue or constipation.
  • If you're taking the oral film, don't chew or swallow it. Let it dissolve naturally on the tongue.
  • It takes 30 minutes for Zofran to start working.
  • Promethazine comes in different forms. Be clear on which one you were prescribed - swallow tablets orally, unwrap and insert suppositories rectally.
  • Don't give to kids 2 and under.
  • You'll likely feel very sleepy, sluggish, or less alert after taking Promethazine. Avoid driving or other tasks that require your focused attention; be safe.
  • Don't drink alcohol to avoid intense side effects.
  • Taking certain medications for pain, allergies, or mood conditions can worsen the side effects of Promethazine.
  • Avoid using if you experience seizures (epilepsy).
  • Don't use if you're 65 or older because you're at higher risk for serious side effects.
Learn more
More about ZofranSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Zofran (ondansetron)?
Worth itNot sureNot worth it
More about PhenerganSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Phenergan (promethazine)?
Worth itNot sureNot worth it