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Drug vs. Drug

Delsym vs. Robitussin DM: Differences, Similarities, and Which One is Better For You

Delsym and Robitussin DM treat cough but work differently
Karen Berger medical writer and reviewer headshot
By | Sep. 9, 2024
Delsym vs. Robitussin DM: Comparing two cough syrup bottles

Key takeaways

  • Delsym contains dextromethorphan and is a cough suppressant. Robitussin DM combines guaifenesin and dextromethorphan, which helps both to thin mucus and suppress cough.

  • Delsym is best for dry, non-productive coughs, whereas Robitussin DM is more suitable for productive coughs with mucus, as it helps clear chest congestion.

  • Both medications may cause dizziness, drowsiness, and nausea. Robitussin DM may also cause stomach pain and headaches due to its guaifenesin content.

  • Both Delsym and Robitussin DM are available over-the-counter, with costs varying by brand or generic formulation and size.

  • Consult your healthcare provider or pharmacist for personalized advice on which medication is best for your symptoms and to avoid potential drug interactions.

In this article:

Delsym and Robitussin DM are two popular over-the-counter medications used to relieve a cough. Both medicines are approved by the U.S. Food and Drug Administration (FDA). Delsym contains the active ingredient dextromethorphan, which works by suppressing a dry cough. Robitussin DM contains two active ingredients. The first ingredient is guaifenesin. It is known as an expectorant and works by thinning out mucus, making it easier to expel. The other ingredient is dextromethorphan, which is the same ingredient that is in Delsym. While these medicines are commonly used for cough, they are not the same. Continue reading to learn more about Delsym and Robitussin DM.

What are the main differences between Delsym and Robitussin DM?

Main differences between Delsym and Robitussin DM
Delsym  Robitussin DM
Drug class Cough suppressant Expectorant and cough suppressant
Brand/generic status Brand and generic  Brand and generic
What is the generic name? Dextromethorphan

(dextromethorphan polistirex)

 Guaifenesin and dextromethorphan
What form(s) does the drug come in? Oral liquid

Oral caplets

 Oral liquid

Oral capsules
How long is the typical treatment? Varies; taken as needed Varies; taken as needed
Who typically uses the medication? Adults and children 4 years and older Adults and children 4 years and older

Delsym contains an extended-release form of the active ingredient dextromethorphan, which allows for every 12-hour dosing. Dextromethorphan works as a cough suppressant and can help a dry, hacking cough. On the other hand, Robitussin DM contains both guaifenesin and dextromethorphan, an expectorant and cough suppressant, respectively. The guaifenesin component helps break up and thin out the mucus, making it easier to clear from the airways, and the dextromethorphan helps control the cough. Therefore, Robitussin DM is more suited for those who have chest congestion or when you feel like you have a wet, mucusy cough. 

It is important to note that there are hundreds of different multi-symptom cough, flu, and cold medicines that contain ingredients such as guaifenesin or dextromethorphan. Many also contain other ingredients, like decongestants (pseudoephedrine), antihistamines (diphenhydramine), and/or acetaminophen. These help with symptoms such as mild pain, fever, runny or stuffy nose, and sore throat. This article, however, will specifically focus on Delsym and Robitussin DM.

 Conditions treated by Delsym and Robitussin DM

Delsym temporarily suppresses a cough caused by minor throat and bronchial irritation, such as from a cold. It helps control the impulse to cough, which can be especially useful for getting a good night’s sleep. However, it does not have a direct sedative effect to make you fall asleep.

Robitussin DM is both a cough suppressant and an expectorant. It temporarily relieves coughs caused by minor throat and bronchial irritation, like those from a cold. Additionally, it helps to loosen phlegm and thin mucus, making it easier to clear from the bronchial tubes.

It’s important to remember that while Delsym and Robitussin DM can help manage symptoms, they do not address the underlying cause of an infection. If you have a bacterial infection, antibiotics may be necessary. These over-the-counter products are intended to provide symptom relief as you recover. Consult a healthcare provider for medical advice.

Is Delsym or Robitussin DM more effective?

When deciding whether Delsym or Robitussin DM is more effective, it depends on the type of cough and symptoms you are experiencing.

Delsym is typically more effective for a dry, non-productive cough. Its extended-release (long-acting) dextromethorphan formulation provides long-lasting relief by suppressing the cough reflex, which is helpful for preventing frequent coughing that disrupts sleep or daily activities.

Robitussin DM is more suitable for a productive cough with mucus. The combination of guaifenesin and dextromethorphan suppresses the cough reflex and helps to thin mucus, making it easier to get rid of. This can be particularly helpful if you are dealing with chest congestion and need to clear mucus from your airways.

You can also check with a healthcare provider or pharmacist to determine the best treatment based on your specific symptoms and health condition.

Coverage and cost comparison of Delsym vs. Robitussin DM

Both Delsym and Robitussin DM are available over-the-counter in various sizes and formulations, as well as in both brand and generic. Therefore, the price will vary based on product selection. You can always ask your pharmacist to help you select a cost-effective product. Most insurance companies and Medicare prescription plans do not cover these medications, with some exceptions.

You can apply a SingleCare discount to your Delsym or Robitussin DM purchase. Note that to use the SingleCare discount, you will need a prescription from a healthcare provider, which the pharmacy staff will use to process the discount.

Some pricing examples follow:

  • A 3-ounce bottle of brand-name Delsym costs about $19. You can use a SingleCare discount to get a 3-ounce bottle of generic Delsym for as low as $5.
  • A 4-ounce bottle of brand-name Robitussin DM costs about $12. You can use a SingleCare discount to get a 4-ounce bottle of generic Robitussin DM for as low as $4.
Delsym  Robitussin DM
Typically covered by insurance? No  No 
Typically covered by Medicare Part D? No  No 
Standard dosage Varies Varies
Typical Medicare copay N/A N/A
SingleCare cost $5 $4

Common side effects of Delsym vs. Robitussin DM

Because both Delsym and Robitussin DM contain dextromethorphan, they share some of the same common side effects of this ingredient, including: 

  • Nausea and vomiting
  • Dizziness
  • Drowsiness 
  • Restlessness 
  • Irritability 

Additionally, because Robitussin DM contains guaifenesin, the following common side effects may also occur in those who take this product:

  • Stomach pain
  • Headache 

As with any medicine, an allergic reaction may occur in rare cases. Get emergency medical help if you have any of the following symptoms after taking Delsym or Robitussin DM:

  • Rash, hives, or itching
  • Difficulty breathing or swallowing
  • Swelling of the face, lips, tongue, or throat

Another potentially serious side effect of Delsym or Robitussin DM is serotonin syndrome. We’ll talk more about that in the Drug interactions section. 

This is not a full list of side effects, and others may occur. Consult your healthcare provider or pharmacist for more information about possible side effects of Delsym and Robitussin DM. 

Drug interactions of Delsym vs. Robitussin DM

Before you take Delsym or Robitussin DM, tell your healthcare provider or pharmacist about all your medications, including prescription and OTC drugs, vitamins, and supplements. 

An important interaction to be aware of is the combination of these medications with others that affect serotonin levels, as this can lead to a potentially life-threatening condition known as serotonin syndrome. Serotonin syndrome is caused by a buildup of excess serotonin in the body and can cause symptoms ranging from mild (such as agitation and anxiety) to life-threatening (such as high fever, seizures, irregular heartbeat, and unconsciousness). If you have symptoms of serotonin syndrome, you should get emergency medical help. 

This interaction specifically applies to dextromethorphan. Therefore, the risk of interaction applies to both medications as they both contain dextromethorphan. While the table below provides examples of medications that can interact, it’s important to note that this is not a list of every possible interaction. Many medications can be involved in this interaction, so always check with a healthcare provider or pharmacist before starting Delsym or Robitussin DM.

Drug Drug Class Interacts with Delsym? Interacts with Robitussin DM?
Escitalopram 

Fluoxetine

Paroxetine

Sertraline

 SSRI antidepressants Yes  Yes
Amitriptyline 

Nortriptyline 

 Tricyclic antidepressants  Yes Yes
Desvenlafaxine

Duloxetine

Venlafaxine

 SNRI antidepressants Yes Yes
Bupropion 

Mirtazapine 

 Other antidepressants  Yes  Yes 
Linezolid 

Phenelzine 

Rasagiline

Selegiline 

Tranylcypromine

 MAO inhibitors Yes (must separate use by at least 14 days) Yes (must separate use by at least 14 days)
Almotriptan 

Eletriptan 

Rizatriptan

Sumatriptan

Zolmitriptan 

 Triptans for migraine treatment Yes Yes
Fentanyl 

Hydrocodone 

Oxycodone 

Tramadol 

 Opioid pain medications  Yes  Yes 
Amphetamine/dextroamphetamine

Methylphenidate 

 Central nervous system (CNS) stimulants  Yes  Yes 
Ondansetron  5-HT3 receptor antagonist Yes  Yes 
Lithium  Antimanic agent  Yes  Yes 
St. John’s wort

Tryptophan 

 Dietary supplements Yes Yes

Warnings of Delsym and Robitussin DM

Before taking Delsym or Robitussin DM, inform your healthcare provider or pharmacist of all your medical conditions, including pregnancy or breastfeeding status. Follow the dosing instructions on the package label carefully. Use the dosing cup provided or a medicinal measuring device for liquid cough syrup formulations, as household spoons are not accurate for measuring medication.

Warnings of both medications include:

  • Do not use Delsym or Robitussin DM if you take a monoamine oxidase inhibitor (MAOI), a drug that may be prescribed for certain mental health conditions or Parkinson’s disease, or within two weeks of taking an MAOI. If you do not know if your medicine contains an MAOI, check with your healthcare provider or pharmacist.
  • If you have a chronic cough from smoking, asthma, or chronic obstructive pulmonary disease (COPD), check with a healthcare provider before using Delsym or Robitussin DM.
  • If your cough lasts more than 7 days, goes away, and returns, or if you have other symptoms such as a fever, rash, or headache, stop using Delsym or Robitussin DM and call your healthcare provider.
  • If you think you took too much medication, get medical help right away or call Poison Control at 800-222-1222.

Frequently asked questions about Delsym vs. Robitussin

What is Delsym?

Delsym is an over-the-counter medication containing the active ingredient dextromethorphan. It is used as a cough suppressant for dry coughs and comes in an extended-release formulation that provides up to 12 hours of cough relief.

What is Robitussin DM?

Robitussin DM is an over-the-counter cough medicine that contains both guaifenesin and dextromethorphan. Guaifenesin is an expectorant (the same ingredient found in Mucinex), which helps loosen and thin mucus, while dextromethorphan suppresses cough.

Are Delsym and Robitussin DM the same?

Delsym and Robitussin DM are not the same. Delsym contains only dextromethorphan and is used to suppress coughs. Robitussin DM contains dextromethorphan and guaifenesin to help suppress cough and relieve mucus.

Is Delsym or Robitussin DM better?

The choice between Delsym and Robitussin DM depends on your symptoms. Delsym is better for a dry cough, while Robitussin DM is better for a wet cough with mucus.

Can I use Delsym or Robitussin DM while pregnant?

Consult your healthcare provider before using Delsym or Robitussin DM during pregnancy. 

Can I use Delsym or Robitussin DM with alcohol?

Combining Delsym or Robitussin DM with alcohol is not recommended. Both medications can cause drowsiness, and drinking alcohol may increase this effect, potentially leading to worsened side effects and impaired judgment. Additionally, alcohol can affect the immune system, which could make it harder for you to recover from your illness.

What is the most effective cough suppressant?

The effectiveness of a cough suppressant depends on the type of cough you have. Delsym contains extended-release dextromethorphan and helps suppress cough, while Robitussin DM is better for “wet” coughs associated with mucus.

Which Robitussin is best for cough?

Robitussin DM is often recommended for a productive cough with mucus due to its combination of an expectorant and a cough suppressant. However, another medicine might be more appropriate if you have a dry cough. Consult a healthcare provider or pharmacist for guidance.

Does Robitussin DM make you stop coughing?

Robitussin DM can help reduce coughing by suppressing the cough reflex and thinning mucus. It helps with coughing associated with chest congestion and mucus production and makes clearing phlegm from your airways easier.