Compare Phenylephrine vs. Benadryl

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

Scroll horizontally → to see comparisons

Sudafed Pe


Clears your sinuses. Sudafed Pe (Phenylephrine) is a good medication for relieving stuffy nose. It doesn't work as well as pseudoephedrine (Sudafed), but it has fewer side effects.Treats allergy symptoms and helps you sleep. Benadryl (Diphenhydramine) is great for allergies, but curl up on the couch after taking it and get ready for a nap.
How it works
Sudafed Pe (Phenylephrine) is a decongestant. It narrows blood vessels and reduces swelling in your nasal passages to make breathing easier.Benadryl (Diphenhydramine) is an antihistamine. It blocks histamine, a chemical that causes congestion, itching, and other allergic reactions. It also makes you sleepy.
Type of medication
DecongestantPrescription or OTC
1st generation
Prescription or OTC
Available as
  • Pill
  • Nasal spray
  • Eye drops
  • Suppository
  • Pill
  • Oral solution
  • Cream, gel, or ointment
Used for (click to learn more)
Find lowest prices
Powered by GoodRxSave on your next prescription. Be sure you’re getting the lowest price for your medication, even if you have insurance.
Reviews & ratings
Button Group. All currently active
Button Group. All currently active
Reviews for Sudafed Pe (Phenylephrine)
of people say Sudafed Pe (Phenylephrine) is worth it
say it works well
say it's a big hassle
Reviews for Benadryl (Diphenhydramine)
+41% vs. Sudafed Pe (Phenylephrine)
+34% vs. Sudafed Pe (Phenylephrine)
+2% vs. Sudafed Pe (Phenylephrine)
Side effects

We haven’t found good data for Phenylephrine side effects.

FDA side effect reports for Phenylephrine »

We haven’t found good data for Benadryl side effects.

FDA side effect reports for Benadryl »
Risk factors for serious side effects
  • History of high blood pressure
  • Taking MAO inhibitors
  • History of heart problems
  • Age 65 years or older
  • Women of childbearing age
Detailed Sudafed Pe (Phenylephrine) risks & warnings »
  • Using other drugs with the same ingredients
  • Age 65 years or older
  • Taking with alcohol
  • Taking other medicines that make you less alert
  • Children age 6 years and younger
  • Enlarged prostate
  • History of bladder problems
  • Glaucoma
  • Nursing mothers
Detailed Benadryl (Diphenhydramine) risks & warnings »
Pregnancy category
CFDA pregnancy category (Weigh risks vs. benefits)

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.

See the FDA package insert
BFDA pregnancy category (Probably safe)

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

See the FDA package insert
No specific alcohol-related info.
  • Don't take it with alcohol or other drugs that make you sleepy.
No specific food-related info.No specific food-related info.
Kidneys and liver
No specific kidneys and liver-related info.No specific kidneys and liver-related info.
No specific sex-related info.No specific sex-related info.
  • Shouldn't use it before you want to sleep.
  • Benadryl (Diphenhydramine) makes you tired, so take it before you go to sleep.
No specific weight-related info.No specific weight-related info.
Upsides and benefits
  • Works to clear nasal congestion and helps you breathe better.
  • Helpful in relieving congestion-related headaches.
  • Has fewer side effects than other decongestants like pseudoephedrine.
  • It doesn't raise your blood pressure and heart rate as much, or cause as much trouble falling asleep.
  • Doesn't give you rebound congestion (worse symptoms when you stop taking it) like nasal spray decongestants do.
  • Benadryl (Diphenhydramine) is often better than other antihistamines at treating allergy symptoms and hives.
  • It can provide quick relief of allergy symptoms for both kids and adults.
  • It makes you sleepy, so it'll help if your allergies are bothering you at night.
  • The effects wear off in 4 to 6 hours, so side effects don't last that long.
  • It comes as a tablet, capsule, liquid, and quick dissolving tablet.
Downsides and risks
  • Phenylephrine doesn't last as long as other decongestants like pseudoephedrine (Sudafed).
  • You shouldn't use it if you have high blood pressure.
  • Can make your heart race or make you feel anxious and restless.
  • Shouldn't use it before you want to sleep.
  • Not as effective after using it for 4 days in a row.
  • Benadryl (Diphenhydramine) makes you more tired than Claritin, Allegra, or Zyrtec.
  • You shouldn't drive after taking Benadryl (Diphenhydramine) until you know how it affects you.
  • Talk to a pediatrician before giving Benadryl (Diphenhydramine) to a child.
  • It can increase the risk of falls, so elderly people shouldn't use Benadryl (Diphenhydramine).
  • Don't use Benadryl (Diphenhydramine) if you are breastfeeding.
Tips from our pharmacists for people taking the medication
  • Starts working in 30 minutes.
  • Phenylephrine can make you restless, so don't take it too close to bedtime.
  • It's in other cold and flu combination medicines. Read labels closely so you don't accidentally double up and take too much of it in a day.
  • Follow age-specific dosing instructions on how much to take.
  • Let your doctor know if your symptoms don't improve in a few days.
  • Take it as needed every 4 to 6 hours.
  • Benadryl (Diphenhydramine) can make you dehydrated, so avoid this side effect by drinking plenty of fluids.
  • Benadryl (Diphenhydramine) makes you tired, so take it before you go to sleep.
  • Don't take it with alcohol or other drugs that make you sleepy.
  • If you need to use it for more than a few weeks, talk with your doctor. A different medication might work better for you long-term.
  • If you only have itchy or watery eyes, try using just an antihistamine eye drop.
Learn more
More about PhenylephrineSide effectsReviews & ratingsAlternativesFDA package insert
More about BenadrylSide effectsReviews & ratingsAlternativesFDA package insert