Compare Delsym vs. Benadryl

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

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Relieves coughing. Delsym (Dextromethorphan) is a good option for treating dry cough. It's not safe to take with MAO inhibitors though.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
Delsym (Dextromethorphan) is a cough suppressant.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
Cough suppressantOver-the-counter
1st generation
Prescription or OTC
Available as
  • Pill
  • Liquid extended release
  • Pill
  • Oral solution
  • Cream, gel, or ointment
Used for (click to learn more)
Find lowest prices
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Reviews & ratings
Button Group. All currently active
Button Group. All currently active
Reviews for Delsym (Dextromethorphan)
of people say Delsym (Dextromethorphan) is worth it
say it works well
say it's a big hassle
Reviews for Benadryl (Diphenhydramine)
+21% vs. Delsym (Dextromethorphan)
+26% vs. Delsym (Dextromethorphan)
+4% vs. Delsym (Dextromethorphan)
Side effects

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

FDA side effect reports for Delsym »

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

FDA side effect reports for Benadryl »
Risk factors for serious side effects
  • Using other medications that affect serotonin
Detailed Delsym (Dextromethorphan) 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
NFDA pregnancy category (Unknown)

The FDA hasn’t classified this medicine’s effects on unborn babies. Talk with your doctor about this medicine if you’re pregnant or planning on it.

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.
No specific sleep-related info.
  • 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
  • Good for treating dry cough.
  • Available in drugstores either by itself or in combination with other medications to treat cold and allergy symptoms.
  • Available as a liquid and a tablet.
  • Some products relieve cough for up to 12 hours.
  • 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
  • Can't take dextromethorphan if you're taking MAO inhibitors (drugs used to treat Parkinson's disease, depression, and other emotional conditions). If taken together, they will cause dangerously high blood pressure levels.
  • If you're taking this in combination with other cold and allergy medications, you should read labels closely to make sure you're not accidentally taking too much of a single ingredient.
  • 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
  • Cough suppressant starts working in 15 to 30 minutes.
  • Follow age-specific dosing instructions on how much to take. Don't take more than the recommended dose.
  • If your cough lasts more than 7 days, call your doctor.
  • 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 DelsymSide effectsReviews & ratingsAlternativesFDA package insert
More about BenadrylSide effectsReviews & ratingsAlternativesFDA package insert