Compare Benadryl vs. Robitussin DM

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

Benadryl
(diphenhydramine)

Robitussin Dm
(guaifenesin / dextromethorphan)

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.Breaks up mucus and relieves cough. Robitussin Dm (Guaifenesin / Dextromethorphan) is okay for loosening congestion in your chest and throat, but it could prevent you from coughing the mucus up. You have to take it more often than other guaifenesin products.
Reviews & ratings
Filter group. All currently selected
Filter group. All currently selected
5.63Benadryl
Reviews for Benadryl
86%
of people (All ages) say Benadryl is worth it
59%
say it works well
8%
say it's a big hassle
294 reviews
Have you used Benadryl (diphenhydramine)?
Worth itNot sureNot worth it
Reviews for Robitussin DM
75%
+11% better vs. Benadryl
37%
+22% better vs. Benadryl
7%
-1% worse vs. Benadryl
724 reviews
Have you used Robitussin Dm (guaifenesin / dextromethorphan)?
Worth itNot sureNot worth it
Side effects
BenadrylRobitussin DM

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

FDA side effect reports for Benadryl »

We haven’t found good data for Robitussin DM side effects.

FDA side effect reports for Robitussin DM »
How it works
BenadrylRobitussin DM
Benadryl (Diphenhydramine) is an antihistamine. It blocks histamine, a chemical that causes congestion, itching, and other allergic reactions. It also makes you sleepy.Robitussin Dm (Guaifenesin / Dextromethorphan) is a combination medicine. Guaifenesin is an expectorant that breaks up and thins out mucus. Dextromethorphan is a cough suppressant.
Type of medication
BenadrylRobitussin DM
Prescription or OTCOver-the-counter
Available as
BenadrylRobitussin DM
  • Pill
  • Oral solution
  • Cream, gel, or ointment
  • Liquid
Used for
BenadrylRobitussin DM
Risk factors for serious side effects
BenadrylRobitussin DM
  • 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
Detailed Benadryl (diphenhydramine) risks & warnings »
  • Using other medications that affect serotonin
Detailed Robitussin Dm (guaifenesin / dextromethorphan) risks & warnings »
Pregnancy

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

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.

Alcohol
BenadrylRobitussin DM
  • Don't take it with alcohol or other drugs that make you sleepy.
No alcohol related info.
Sleep
BenadrylRobitussin DM
  • Benadryl (Diphenhydramine) makes you tired, so take it before you go to sleep.
  • Benadryl (Diphenhydramine) makes you more tired than Claritin, Allegra, or Zyrtec.
No sleep related info.
Upsides and benefits
BenadrylRobitussin DM
  • 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.
  • Robitussin Dm (Guaifenesin / Dextromethorphan) is a combination medicine that relieves multiple cold symptoms. It's good to use if you have chest congestion and a cough.
  • Helps loosen the mucus and phlegm that builds up and causes productive, wet coughs.
Downsides and risks
BenadrylRobitussin DM
  • 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.
  • Robitussin Dm (Guaifenesin / Dextromethorphan) isn’t useful if you have a dry cough without mucus or phlegm.
  • The two medications in this product could potentially work against each other. Guaifenesin makes mucus easier to cough up, while dextromethorphan (the "DM" in Robitussin Dm (Guaifenesin / Dextromethorphan)) stops you from coughing.
  • Needs to be taken more often during the day than other products with guaifenesin, like Mucinex.
  • Can cause sleepiness, dizziness, and an upset stomach.
Tips from our pharmacists for people taking the medication
BenadrylRobitussin DM
  • 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.
  • Drink plenty of fluids while taking Robitussin Dm (Guaifenesin / Dextromethorphan) because liquid helps break down mucus.
  • 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.
Learn more
More about BenadrylSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Benadryl (diphenhydramine)?
Worth itNot sureNot worth it
More about Robitussin DMSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Robitussin Dm (guaifenesin / dextromethorphan)?
Worth itNot sureNot worth it