Karbinal ER (Carbinoxamine) – Oral

What Is Karbinal ER?

Karbinal ER (carbinoxamine) is an oral prescription drug used to treat allergies, hives, and other allergic conditions in adults and children 2 years and older.

Karbinal ER is in a drug class called antihistamines. Histamine is a substance that the body makes when it is exposed to allergens. Histamine brings on allergy symptoms. By blocking histamine, Karbinal ER reduces allergy symptoms.

It is available as an oral liquid suspension. Karbinal ER is an extended-release version of carbinoxamine, meaning the drug is released slowly into the body over a 12-hour period.

Drug Facts

Generic Name: Carbinoxamine

Brand Name(s): Karbinal ER (extended-release)

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Antihistamine

Available Generically: No

Controlled Substance: N/A

Active Ingredient: Carbinoxamine

Dosage Form(s): Suspension

What Is Karbinal ER Used For?

The Food and Drug Administration (FDA) approved Karbinal ER in adults and children 2 years and older to treat:

  • Seasonal and perennial (year-round) allergies
  • Vasomotor rhinitis (also known as nonallergic rhinitis, this condition occurs from swollen nasal tissue)
  • Allergic pink eye due to inhalant allergens and foods
  • Mild allergic skin symptoms of urticaria (hives) and angioedema (swelling under the skin)
  • Dermatographism (known as "writing on the skin," a skin reaction of hives caused by pressure on the skin)
  • As treatment for anaphylactic (severe allergic) reactions in combination with epinephrine and other measures after the acute symptoms are under control
  • Lessening the severity of allergic reactions to blood or plasma

How to Take Karbinal ER

If you are prescribed Karbinal ER, make sure to read the prescription label and the information leaflet. Use Karbinal ER exactly as directed by your healthcare provider.

Karbinal ER comes in a liquid suspension. Before taking it, shake the suspension and measure out the dose with the oral syringe provided with it or a medication measuring device. Do not use a kitchen spoon or household device, as these are inaccurate.

Follow directions closely when giving Karbinal ER to a child. Although it has a sedative effect, you should not use it to try to make a child drowsy. Misusing Karbinal ER can be dangerous for young children.

Because Karbinal ER may cause drowsiness, do not drive or operate machinery while taking this medication until you know how it will affect you. Avoid drinking alcohol or smoking marijuana while taking it.

Certain medications should also not be taken with it, such as muscle relaxants or drugs used for sleep, anxiety, or severe pain. Ask your healthcare provider or pharmacist for a complete list of drugs to avoid while using Karbinal ER.

Call your healthcare provider if your symptoms worsen or do not improve.

Storage

Store Karbinal ER at room temperature (between 68 and 77 degrees F), away from light, heat, and moisture. Keep the bottle tightly closed and out of reach of children and pets.

What Are the Side Effects of Karbinal ER?

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 www.fda.gov/medwatch or 800-FDA-1088.

Like other medications, Karbinal ER can cause side effects. Tell your healthcare provider about any side effects you experience while taking this medication.

Common Side Effects

Common side effects of Karbinal ER include:

  • Blurry or double vision
  • Constipation
  • Discomfort while urinating; difficulty emptying the bladder
  • Dizziness and drowsiness
  • Dry mucous membranes (nose, mouth)
  • Excessive sweating
  • Headache
  • Impaired coordination
  • Low blood pressure
  • Palpitations (feeling like the heart is racing, pounding, or fluttering)
  • Sun sensitivity
  • Tachycardia (fast heart rate)
  • Thickened bronchial secretions (mucus that comes from the lungs)
  • Upper abdominal pain

Severe Side Effects

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

  • Hypersensitivity reaction or anaphylaxis (a life-threatening reaction): Symptoms can include rash, hives, difficulty breathing, and swelling around the lips, tongue, and face.
  • Hemolytic anemia (a condition in which red blood cells are destroyed faster than they are made): Symptoms can include breathing difficulties with physical activity, fatigue, dizziness, or an irregular heartbeat.
  • Low platelet levels, which can increase the risk of bleeding: Symptoms can include bruising easily, petechiae (tiny red spots on the skin), excess bleeding after minor injuries, and frequent nosebleeds.
  • Low levels of white blood cells (agranulocytosis), which can increase the risk of infection: Symptoms may include fever, increased heart rate, a sudden drop in blood pressure, weakness, and sores in the mouth and throat.
  • Irregular heartbeat, which can include a racing, skipping, or fluttering sensation in your chest
  • Seizures
  • Acute labyrinthitis (inflammation of the inner ear that can affect balance)

Long-Term Side Effects

While many people tolerate Karbinal ER well, especially since it is usually taken for a short time, long-term or delayed side effects are possible. Some long-term side effects can be mild, such as:

  • Appetite loss
  • Irritability
  • Sun sensitivity

Moderate long-term side effects can include:

  • Constipation
  • Impaired coordination

Severe long-term side effects may include:

  • Seizures

Report Side Effects

Karbinal ER 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 healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Karbinal ER 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 treatment of allergies:
    • For oral dosage form (extended-release suspension):
      • Adults and children 12 years of age and older—6 to 16 milligrams (mg) or 7.5 to 20 milliliters (mL) every 12 hours. Your doctor may adjust your dose as needed.
      • Children 6 to 11 years of age—Dose is based on body weight and must be determined by your doctor. The dose is usually 6 to 12 mg or 7.5 to 15 mL every 12 hours. Your doctor may adjust your dose as needed.
      • Children 4 to 5 years of age—Dose is based on body weight and must be determined by your doctor. The dose is usually 3 to 8 mg or 3.75 to 10 mL every 12 hours. Your doctor may adjust your dose as needed.
      • Children 2 to 3 years of age—Dose is based on body weight and must be determined by your doctor. The dose is usually 3 to 4 mg or 3.75 to 5 mL every 12 hours. Your doctor may adjust your dose as needed.
      • Children younger than 2 years of age—Use is not recommended.
    • For oral dosage form (solution):
      • Adults and children 12 years of age and older—4 to 8 milligrams (mg) (1 or 2 teaspoonfuls) 3 to 4 times a day. Your doctor may adjust your dose as needed.
      • Children 6 to 11 years of age—2 to 4 mg (½ to 1 teaspoonful) 3 to 4 times a day. Your doctor may adjust your dose as needed.
      • Children 2 to 5 years of age—Dose is based on body weight and must be determined by your doctor. The dose is usually 1 to 2 mg (¼ to ½ teaspoonful) 3 to 4 times a day. Your doctor may adjust your dose as needed.
      • Children younger than 2 years of age—Use is not recommended.
    • For oral dosage form (tablets):
      • Adults and children 12 years of age and older—4 to 8 milligrams (mg) (1 or 2 tablets) 3 to 4 times a day. Your doctor may adjust your dose as needed.
      • Children 6 to 11 years of age—2 to 4 mg (½ to 1 tablet) 3 to 4 times a day. Your doctor may adjust your dose as needed.
      • Children younger than 2 years of age—Use is not recommended.

Modifications

Certain factors may necessitate a dosage change or treatment adjustment while taking Karbinal ER:

  • Age 65 and older: You may need to use caution when taking Karbinal ER if you are 65 years or older, as this medcation is more likely to cause adverse effects such as dizziness, low blood pressure, confusion, or excess sedation in older adults. Your healthcare provider may recommend a lower dosage and closer monitoring.
  • Young children: Although this medication can cause sedation, it might also have the opposite effect in younger children and cause excitation. Never give this medication to children younger than 2 years old.
  • Kidney or liver problems: Consult your healthcare provider before taking Karbinal ER if you have liver or kidney impairment.
  • Pregnancy and breastfeeding: Talk to your healthcare provider if you are pregnant or plan to become pregnant while using Karbinal ER. It is not recommended to breastfeed during treatment, as the drug may cause drowsiness and irritability in breastfed infants.

Missed Dose

Because Karbinal ER is taken when needed, a missed dose should be skipped. Resume the next dose at the regular time. Do not take two doses to try to catch up on a missed dose.

Overdose: What Happens If I Take Too Much Karbinal ER?

Taking too much Karbinal ER can cause the following symptoms:

  • Extreme drowsiness
  • Restlessness
  • Hallucinations (seeing, hearing, and believing things that are not there)
  • Dry mouth
  • Dilated pupils
  • Seizures

An overdose can cause death, especially in children.

What Happens If I Overdose on Karbinal ER?

If you think you or someone else may have overdosed on Karbinal ER, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Karbinal ER, call 911 immediately.

Precautions

Drug Content Provided and Reviewed by IBM Micromedex®

If you will be taking this medicine for a long time, it is very important that your doctor check you or your child at regular visits. This will allow your doctor to see if the medicine is working properly and to check for any unwanted effects.

Do not use this medicine if you are using an MAO inhibitor (MAOI) such as Eldepryl®, Marplan®, Nardil®, or Parnate®.

This medicine may cause some people to become dizzy, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert and not able to think well.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds, sedatives, tranquilizers, or sleeping medicine, prescription pain medicine or narcotics, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your medical doctor or dentist before taking any of the above while you are taking this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn't Take Karbinal ER?

Karbinal ER is not appropriate for everyone. You should not take this medication if you are allergic to carbinoxamine or any of the inactive ingredients in Karbinal ER.

Other people who should not take Karbinal ER include:

  • Infants and children under 2 years old
  • Women who are breastfeeding

Also, it is important to avoid alcohol and cannabis (marijuana) while taking Karbinal ER. Karbinal ER also should not be taken in combination with other medicines that cause central nervous system (CNS) depression. CNS depression is a slowing of the nervous system, which can cause drowsiness and slowed breathing.

Examples of drugs that cause CNS depression include:

  • Muscle relaxants
  • Anxiety medications
  • Sleep medications
  • Medications for severe pain

Karbinal ER may be prescribed with caution in some people, only if the healthcare provider determines it is safe. This includes young children and older adults (aged 65 and older), as well as people with the following conditions:

What Other Medications May Interact With Karbinal ER?

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter (OTC) medications, and vitamins or supplements. 

Karbinal ER should not be combined with monoamine oxidase inhibitors (MAOIs) because they can worsen the drying effects of Karbinal ER. Examples of MAOIs include but are not limited to:

Karbinal ER should not be combined with other drugs or substances that cause CNS depression, such as:

Karbinal ER should not be taken with solid forms of potassium, such as potassium tablets, because these types of potassium may cause ulcers when combined with Karbinal ER. Consult your healthcare provider if you take potassium.

Other drug interactions may occur with Karbinal ER. Consult your healthcare provider for a complete list of drug interactions.

What Medications Are Similar?

Carbinoxamine, the active ingredient in Karbinal ER, is a first-generation antihistamine. First-generation antihistamines are older and tend to cause more side effects, such as sedation, fatigue, and impaired coordination. Examples of other first-generation antihistamines include:

  • Vistaril (hydroxyzine)
  • Benadryl (diphenhydramine)
  • Veltane (brompheniramine)
  • Doxylamine (this antihistamine is often used as a sleep aid, found in brand-name products such as Unisom)

Some of these first-generation antihistamines can also be found in various cough and cold medications (OTC or prescription) in combination with other ingredients.

Second-generation antihistamines, which are effective but tend to cause less drowsiness, include:

Frequently Asked Questions

  • What is Karbinal ER used for?

    Karbinal ER is used to treat allergies, hives, and various other allergic conditions in adults and children 2 years and older.

  • How does Karbinal ER work?

    Karbinal ER is an antihistamine. The body makes histamine when it is exposed to allergens, which, in turn, brings on allergy symptoms. Blocking histamine helps reduce allergy symptoms. Karbinal ER is described in the prescribing information as having a drying and sedating effect.

  • What drugs should not be taken with Karbinal ER?

    Karbinal ER should not be combined with other antihistamines, alcohol, cannabis (marijuana), or drugs such as muscle relaxants, sleeping medicines, anxiety medications, or pain medications. It should not be used in combination with MAOI drugs or solid forms of potassium, such as tablets.

    Before taking Karbinal ER, tell your healthcare provider about all of the medications you take, including prescription and OTC drugs, vitamins, and supplements.

  • What are the side effects of Karbinal ER?

    Common side effects include vision disturbances, dizziness, drowsiness, impaired coordination, sweating, headache, low blood pressure, constipation, and dryness (in the nose and mouth). Other side effects include difficulty urinating, headache, sun sensitivity, and irregular heartbeat.

  • How do I stop taking Karbinal ER?

    Your healthcare provider will tell you how long to take Karbinal ER.

How Can I Stay Healthy While Taking Karbinal ER?

Consult your healthcare provider about the best treatment for your allergies. You may want to schedule an appointment with an allergist, who can perform allergy testing and recommend the best therapeutic option. If you are at risk for a serious allergic reaction, carry an epinephrine injection with you everywhere you go. Wear a medical alert ID if you have ever had a serious allergic reaction.

In addition to taking Karbinal ER, here are some non-medicinal measures you can take to help prevent allergy symptoms:

  • Monitor pollen and mold counts. You can use various phone apps and/or general news and weather reports.
  • Close the doors and windows at home and in your car when experiencing allergy symptoms.
  • Wash your body and hair and put on clean clothes after coming in from spending time outside.
  • Wear an N95 mask when outside.
  • Use an air purifier and/or a humidifier.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace 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.

5 Sources
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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  2. DailyMed. Label: Karbinal ER- carbinoxamine maleate suspension, extended release.

  3. Meyers RS, Thackray J, Matson KL, et al. Key potentially inappropriate drugs in pediatrics: the KIDs list. J Pediatr Pharmacol Ther. 2020;25(3):175–191. doi:10.5863/1551-6776-25.3.175

  4. Epocrates. Karbinal ER.

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By Karen Berger, PharmD
Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.