Compare Benadryl vs. Robitussin

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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 that causes cough. Robitussin (Guaifenesin) is a useful medicine for loosening congestion in your chest and throat, but it doesn't last as long as other guaifenesin products.
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Reviews & ratings
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Reviews for Benadryl (Diphenhydramine)
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Side effects

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

FDA side effect reports for Benadryl »

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

FDA side effect reports for Robitussin »
How it works
Benadryl (Diphenhydramine) is an antihistamine. It blocks histamine, a chemical that causes congestion, itching, and other allergic reactions. It also makes you sleepy.Robitussin (Guaifenesin) is an expectorant. It contains guaifenesin, which thins and loosens mucus, making it easier to cough out.
Type of medication
1st generation
Prescription or OTC
Available as
  • Pill
  • Oral solution
  • Cream, gel, or ointment
  • Liquid
Used for (click to learn more)
Risk factors for serious side effects
  • 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 »
    Detailed Robitussin (Guaifenesin) risks & warnings »
    Pregnancy category
    • Don't take it with alcohol or other drugs that make you sleepy.
    No specific alcohol-related info.
    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.
    • Benadryl (Diphenhydramine) makes you tired, so take it before you go to sleep.
    No specific sleep-related info.
    No specific weight-related info.No specific weight-related info.
    Upsides and benefits
    • 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 (Guaifenesin) reduces the thickness and amount of mucus in your throat and chest.
    • It’s available at the drugstore either by itself or in combination with other medications to treat cold and flu symptoms.
    • Available in multiple forms.
    • Can be used in children 12 years and older.
    Downsides and risks
    • 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 (Guaifenesin) doesn't last as long as other products that contain guaifenesin. Mucinex's extended release form lasts 12 hours and Robitussin (Guaifenesin)'s lasts 8 hours.
    • You need to drink a lot of fluids while taking this medication or it won't work as well.
    • Robitussin (Guaifenesin) isn’t useful if you have a dry cough.
    • Can cause nausea, headache, and an upset stomach.
    Tips from our pharmacists for people taking the medication
    • 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 (Guaifenesin) because liquid helps break down mucus.
    • Steam from a humidifier, cool mist vaporizer, or hot shower can also help add moisture to your airways.
    • Follow age-specific dosing instructions on how much to take.
    • If your cough lasts more than 7 days, call your doctor.
    • Robitussin (Guaifenesin) only works for coughs with mucus, so don't use it if you have a dry cough.
    Learn more
    More about BenadrylSide effectsReviews & ratingsAlternativesFDA package insert
    More about RobitussinSide effectsReviews & ratingsAlternativesFDA package insert