Delsym (Dextromethorphan) - Oral

What Is Delsym?

Delsym (dextromethorphan) is an over-the-counter (OTC) cough syrup that is used often during cold and flu season to relieve cough

Although Delsym has been available for a relatively long time, how it works is not completely known. However, medical experts believe that Delsym may work by mimicking another medication, codeine, a drug in the opioid class. Delsym may also block special proteins in the brain cells called receptors, specifically the N-methyl-D-aspartate (NMDA) and serotonin receptors. These receptors were found in clinical trials to play a role in causing coughing.

Delsym comes in either immediate-release or extended-release (slowly released in the body) formulations.

Drug Facts

Generic Name: Dextromethorphan

Brand Name(s): Delsym

Administration Route(s): Oral

Drug Availability: Prescription

Therapeutic Classification: Antitussive

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Dextromethorphan

Dosage Form(s): Syrup

What Is Delsym Used For?

The Food and Drug Administration (FDA) approved Delsym for the temporary relief of the following:

  • Cough caused by scratchy feeling in your throat that can occur as a cold symptom
  • Control cough to help aid in sleep
Delsym (Dextromethorphan) Drug Information - Man coughing and areas highlighted where Delysum affects

Verywell / Dennis Madamba

How to Take Delsym

Delsym should generally be taken by mouth every four to eight hours for immediate-release medications. Extended-release medications can be taken by mouth every 12 hours.

The specific volume will vary depending on certain characteristics like age. Dextromethorphan should not be taken if you take medications in the monoamine oxidase inhibitor (MAOI) drug class. It can lead to a condition known as serotonin syndrome.


Store Delsym in a cool, dry place. Generally, you should keep medications away from spaces that endure heat, like your car, or high humidity areas, like your bathroom. These kinds of factors can impact how well medications work. It’s also important to make sure medications are away from pets and children to avoid accidental consumption.

Off-Label Uses

Dextromethorphan has been around for a long time and has a lot of time to be studied in various other conditions.

Examples of those are listed below:

  • Pain relief
  • Diabetes complications
  • Combination with quinidine to treat depression
  • Combination with quinidine to treat pseudobulbar affect

Pain Relief

Compared with ibuprofen, dextromethorphan was found to have no effect on overall pain relief after major surgery at low doses. However, at relatively higher doses, dextromethorphan decreased pain when given for minor surgeries. One study found that dextromethorphan may have led to a lower dose of a powerful opiate called morphine.

Diabetes Complications

Another study found that dextromethorphan might affect a diabetes complication known as macular edema. Diabetes can cause macular edema by the breakdown of the blood-brain barrier, which is a barrier that separates fluids in your brain and fluids in your spinal cord. The nature of macular edema is progressive, which means it worsens over time. This study found that people taking dextromethorphan didn’t get worse in macular edema.

Combination Treatment With Quinidine

Dextromethorphan has shown even more potential when combined with another medication, quinidine. Quinidine is a medication that is used to treat parasites, as well as treat irregular heartbeats. One study found that this combination could potentially manage the symptoms of depression. 

More data show that this combination is effective in treating a disorder known as pseudobulbar affect. Pseudobulbar affect is characterized by sudden and often uncontrollable laughter or crying. The combination of dextromethorphan and quinidine was shown to have significant improvements in treating the symptoms of pseudobulbar affect.

How Long Does Delsym Take to Work?

Delsym will take around 30 minutes for it to start relieving your cough symptoms.

What Are the Side Effects of Delsym?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at or 1-800-FDA-1088.

Common Side Effects

The following side effects are commonly reported in those that take Delsym:

  • Drowsiness
  • Dizziness
  • Fatigue
  • Nausea
  • Stomach ache
  • Jitteriness
  • Itchiness

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects can include:

Long-Term Side Effects

Delsym is a relatively well-tolerated medication.

However, when taken for a long time, Delsym can cause side effects such as:

  • Decreased attention span and concentration
  • Decreased ability to control movements
  • Fatigue
  • Hallucinations
  • Confusion
  • Depression

Report Side Effects

Delsym may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much of Delsym Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For lozenge dosage form:
    • For cough:
      • Adults and children 12 years of age and older—5 to 15 mg every two to four hours, as needed.
      • Children 6 to 12 years of age—5 to 15 mg every two to six hours, as needed.
      • Children 4 to 6 years of age—5 mg every four hours, as needed.
      • Children and infants up to 4 years of age—Use is not recommended .
  • For syrup dosage form:
    • For cough:
      • Adults and children 12 years of age and older—30 mg every six to eight hours, as needed.
      • Children 6 to 12 years of age—7 mg every four hours or 15 mg every six to eight hours, as needed.
      • Children 4 to 6 years of age—3.5 mg every four hours or 7.5 mg every six to eight hours, as needed.
      • Children and infants up to 4 years of age—Use is not recommended .
  • For extended-release oral suspension dosage form :
    • For cough:
      • Adults and children 12 years of age and older—60 mg every twelve hours, as needed.
      • Children 6 to 12 years of age—30 mg every twelve hours, as needed.
      • Children 4 to 6 years of age—15 mg every twelve hours, as needed.
      • Children and infants up to 4 years of age—Use is not recommended .


Delsym is considered acceptable for use during pregnancy at standard OTC doses.

While using Delsym, you should avoid taking products containing alcohol. Some people are also considered “poor metabolizers,” which means they have less of an enzyme that converts and breaks down Delsym in the body. This may cause an increase in side effects while taking the medication but does not necessitate a change in dose.

Missed Dose

If you miss a dose of Delsym, it will be okay. What’s important is you take it as soon as you remember. Even if you miss a dose, continue only to take the normal recommended dose. Do not take more to make up for the missed one.

Overdose: What Happens If I Take Too Much Delsym?

There is no set dose that indicates an overdosage of Delsym. However, an overdose may cause the following symptoms:

  • Abnormally large pupils
  • Hallucinations
  • Nausea
  • Vomiting
  • Abnormal movements
  • Agitation

If you experience these symptoms or see someone experiencing these symptoms after the consumption of Delsym, it’s very important to contact a poison control center or call 911 immediately. The sooner you get treated, the less likely it will be that complications occur.

What Happens If I Overdose on Delsym?

Delsym may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).


Drug Content Provided and Reviewed by IBM Micromedex®

If your cough has not improved after 7 days, if sore throat has not improved after 2 days, if you have a high fever, skin rash, or continuing headache with the cough, or if asthma or high blood pressure is present, check with your doctor. These signs may mean that you have other medical problems.

Dissolve lozenges in the mouth with caution, to lessen the risk of choking.

What Are Reasons I Shouldn’t Take Delsym?

Do not take Delsym within 14 days of taking an MAOI inhibitor. If you plan on taking Delsym, you must know if you are taking a drug in that class. MAOIs can be used for depression, mood disorders, or Parkinson’s syndrome. When Delsym is taken with monoamine oxidase inhibitors, serotonin syndrome is more likely.

Serotonin syndrome is a condition in which there is a dangerous increase in the concentrations of serotonin in your blood. Serotonin controls how your intestines digest food, how well your heart functions, and how you feel. However, whenever there is too much serotonin in your blood, the following symptoms may occur: 

  • Anxiety
  • Confusion
  • Irregular heartbeat
  • Loss of coordination
  • Jerky movements
  • Tremors

What Other Medications Interact With Delsym?

Delsym is converted in the body by a protein family known as the CYP450 family or cytochrome P450s. There are many CYP450 sub-families, including the 2D6 sub-family. Dextromethorphan is almost completely metabolized by CYP4502D6, or CYP2D6.

The medications that may interact with Delsym are drugs that impact how well CYP2D6 works. Some medications (CYP2D6 inhibitors) can decrease the action of CYP2D6, which increases the amount of Delsym in your body.

Examples of CYP2D6 inhibitors include:

  • Bupropion
  • Fluoxetine
  • Paroxetine
  • Terbinafine
  • Quinidine

Conversely, some medications (CYP2D6 inducers) can increase the action of CYP2D6, which decreases the Delsym in your body. 

Examples of CYP2D6 inducers are below.

  • Dexamethasone
  • Rifampin

What Medications Are Similar?

Delsym is a very common medication used during cold and flu season, but it is not the only medication that can treat a cough. Some examples of other cough medications include:

Benzonatate, available under the brand names Tessalon Perles and Zonatuss, is a cough medication similar to dextromethorphan. Both dextromethorphan and benzonatate are unlikely to be addictive since neither is in the opioid drug class. Compared with drugs in the opioid class (like codeine), Delsym and benzonatate tend to have fewer side effects.

Codeine is part of the opioid drug class. Delsym was found to work as well, or sometimes better, than codeine in cough relief in clinical studies.

Robitussin has the same active ingredient as Delsym (dextromethorphan).

Guaifenesin, available under brand names such as Mucinex, is not a cough suppressant but is often used for cough because it helps thin mucus. Cough preparations often will have both guaifenesin and dextromethorphan together.

This list is a list of drugs also prescribed for the targeted condition(s). It is NOT a list of drugs recommended to take with Delsym. In fact, some of these drugs you should not take together. For example, Robitussin and Delsym should NOT be taken together; they both have the same active ingredient, and you risk overdose. Ask your pharmacist or a healthcare practitioner if you have questions.

Frequently Asked Questions

  • Can I travel with Delsym?

    Since Delsym is a liquid, it must be able to fit within a 3.4 ounce or quart-sized bag per TSA requirements. If you forget your medication at home and are traveling internationally, you might be able to purchase Delsym at your destination. That is heavily dependent on local laws and rules. If you travel within the United States, you can simply go to your nearest pharmacy and buy a new bottle.

  • How can I manage the side effects of Delsym?

    If you experience a stomach ache, nausea, or other symptoms of an upset stomach, it is okay if you take Delsym with some food or milk. A healthy diet with ample amounts of fiber can help lessen the risk of constipation.

  • How much does Delsym cost? Is there a way I can get help paying for it?

    Delsym is one of the brand names for dextromethorphan. In the United States, it might cost around $15 for 90 milliliters. Robitussin, another brand name for dextromethorphan, might also cost around the same amount. 
    There are also generic formulations sold in many pharmacies that can be cheaper. When looking for generic forms, check the active ingredient to make sure you are purchasing the correct medication.

How Can I Stay Healthy While Taking Delsym?

Although remembering to take a medication can be difficult at first, it’s important to take Delsym regularly to help minimize your coughing symptoms.

In addition to taking your medication, make sure to get lots of rest, stay hydrated, and eat a healthy diet. Although you may not feel the best whenever you have a cough from a cold or flu, having a healthy lifestyle can improve how quickly you recover. Contact your healthcare provider if your symptoms worsen, and OTC medications are not working.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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