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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Other
Carbinoxamine is a first-generation antihistamine of the ethanolamine class used to treat allergic rhinitis, vasomotor rhinitis, and allergic conjunctivitis by blocking H1 receptors.
Name
Carbinoxamine
Raw Name
CARBINOXAMINE MALEATE
Category
Other
Salt Form
Maleate
Drug Count
5
Variant Count
10
Last Verified
February 17, 2026
RxCUI
1010696, 1012904, 1374770, 1374776, 1795581, 1869883, 2730039
UNII
02O55696WH
About Carbinoxamine
Carbinoxamine is a first-generation antihistamine of the ethanolamine class used to treat allergic rhinitis, vasomotor rhinitis, and allergic conjunctivitis by blocking H1 receptors.
Detailed information about Carbinoxamine
This page is for informational purposes only and does not replace medical advice. Consult a qualified healthcare professional before using any medication containing Carbinoxamine.
Historically, carbinoxamine has been available in various formulations for decades, serving as a cornerstone in the management of seasonal and perennial allergic rhinitis (hay fever). It is classified pharmacologically as an H1-receptor antagonist. Unlike second-generation antihistamines (such as loratadine or cetirizine), first-generation agents like carbinoxamine readily cross the blood-brain barrier (a protective membrane that regulates the entry of substances into the brain), which accounts for its sedative properties. Healthcare providers typically prescribe carbinoxamine when patients require relief from sneezing, rhinorrhea (runny nose), and itchy, watery eyes associated with environmental allergens.
At the molecular level, carbinoxamine works by acting as a competitive antagonist at the H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract. Histamine is a naturally occurring chemical in the body that, when released during an allergic reaction, binds to H1 receptors, causing blood vessels to dilate and become 'leaky,' leading to swelling (edema), itching, and mucus production. Carbinoxamine 'competes' with histamine for these receptor sites. By occupying the receptor without activating it, carbinoxamine prevents histamine from exerting its inflammatory effects.
Furthermore, carbinoxamine possesses significant anticholinergic (antimuscarinic) activity. This means it blocks acetylcholine receptors, which leads to a 'drying' effect on the mucous membranes of the nose and throat. While this helps reduce a runny nose, it also contributes to common side effects like dry mouth and blurred vision. Because it crosses the blood-brain barrier, it also interferes with histamine's role in maintaining wakefulness in the brain, which is why sedation is a primary clinical effect of this medication.
Understanding the pharmacokinetics (how the body processes the drug) of carbinoxamine is essential for clinical management.
Carbinoxamine is FDA-approved for the following indications:
Off-label, it has occasionally been used for its sedative properties in mild insomnia, although this is generally discouraged by modern clinical guidelines in favor of safer alternatives.
Carbinoxamine is available in several oral dosage forms to accommodate different patient needs:
> Important: Only your healthcare provider can determine if Carbinoxamine is right for your specific condition. Always consult with a medical professional before starting a new medication regimen.
For adults and adolescents aged 12 years and older, the standard recommended dosage of carbinoxamine maleate is 4 mg to 8 mg taken orally three to four times daily. The maximum daily dose should generally not exceed 32 mg. Healthcare providers often recommend starting at the lower end of the dosing spectrum to assess the patient's tolerance to the sedative effects. For extended-release formulations, the typical dose is 8 mg to 16 mg taken every 12 hours.
Carbinoxamine must be used with extreme caution in children. According to the American Academy of Pediatrics and FDA guidelines, carbinoxamine is generally contraindicated in infants under the age of 2 due to the risk of fatal respiratory depression.
There are no specific quantitative guidelines for carbinoxamine dosing in patients with kidney disease. However, because the drug is excreted renally, healthcare providers typically exercise caution and may reduce the frequency of dosing in patients with significant renal impairment to prevent drug accumulation and toxicity.
Since carbinoxamine is extensively metabolized by the liver, patients with hepatic insufficiency (liver failure or cirrhosis) may experience higher plasma levels of the drug. Lower initial doses and careful monitoring for increased sedation are recommended.
Patients over the age of 65 are more susceptible to the side effects of first-generation antihistamines. The Beers Criteria (a guideline for safe medication use in seniors) lists carbinoxamine as a potentially inappropriate medication for the elderly due to the high risk of confusion, dizziness, urinary retention, and falls. If used, the lowest possible dose should be initiated.
Carbinoxamine can be taken with or without food. If the medication causes stomach upset, taking it with a meal or a glass of milk may help. For liquid forms, it is critical to use a calibrated measuring device (oral syringe or dosing cup) rather than a household teaspoon to ensure accurate dosing. Tablets should be swallowed whole with water. If using the extended-release suspension, the bottle must be shaken vigorously before each use to ensure the medication is evenly distributed.
If a dose of carbinoxamine is missed, it should be taken as soon as the patient remembers. However, if it is almost time for the next scheduled dose, the missed dose should be skipped, and the regular schedule should be resumed. Patients should never 'double up' or take two doses at once to make up for a missed one, as this significantly increases the risk of CNS depression and anticholinergic toxicity.
An overdose of carbinoxamine can be life-threatening, particularly in children. Symptoms of overdose include extreme drowsiness, dilated pupils, flushed skin, fever, hallucinations, tremors, and in severe cases, seizures or cardiovascular collapse. In children, an overdose may paradoxically cause excitation and hyperactivity before progressing to coma. If an overdose is suspected, contact a Poison Control Center (1-800-222-1222 in the US) or seek emergency medical attention immediately.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop the medication without medical guidance, as this could lead to a return of symptoms or unexpected side effects.
The most frequently reported side effect of carbinoxamine is central nervous system depression, specifically somnolence (drowsiness). Studies suggest that more than 10% of patients will experience some degree of sedation. This effect is often most pronounced during the first few days of therapy and may diminish as the body adjusts to the medication. Other very common effects include:
These effects occur in a smaller percentage of the population but are still clinically significant:
Rarely, patients may experience more severe or unusual reactions:
> Warning: Stop taking Carbinoxamine and call your doctor immediately if you experience any of the following:
Prolonged use of carbinoxamine can lead to several chronic issues. One major concern is the development of tolerance, where the body becomes accustomed to the drug and it no longer provides the same level of symptom relief. Additionally, chronic dry mouth (xerostomia) can significantly increase the risk of dental caries (cavities), gum disease, and oral fungal infections (thrush) because saliva is necessary to neutralize acids and wash away bacteria. Long-term use in the elderly has also been linked to an increased risk of cognitive decline and dementia, according to some observational studies regarding anticholinergic burden.
There are currently no FDA-mandated Black Box Warnings specifically for carbinoxamine. However, the FDA has issued strong safety communications regarding the use of all first-generation antihistamines in children under the age of 2. These warnings emphasize that carbinoxamine is contraindicated in this age group due to the risk of respiratory depression, which can be fatal. Manufacturers are required to include clear contraindications for infants in their professional labeling.
Report any unusual symptoms or persistent side effects to your healthcare provider. Monitoring the frequency and severity of these effects is crucial for ensuring the medication remains a safe option for your allergy management.
Carbinoxamine is a potent medication that requires careful management. Patients must be aware that this drug significantly impairs mental alertness and physical coordination. Activities requiring high levels of concentration, such as driving a motor vehicle or operating heavy machinery, should be avoided until the patient is certain that the medication does not cause excessive drowsiness or dizziness. Furthermore, carbinoxamine should be used with caution in individuals with a history of asthma, as its drying effect can lead to the thickening of bronchial secretions, potentially complicating an asthma attack.
No FDA black box warnings for Carbinoxamine. However, the contraindication for use in children under 2 years of age is considered a high-priority safety warning by the FDA and clinical organizations like the American Academy of Pediatrics.
For most patients taking carbinoxamine for short-term allergy relief, intensive laboratory monitoring is not required. However, for those on long-term therapy, healthcare providers may occasionally order:
As previously noted, the sedative effect of carbinoxamine is substantial. The drug's ability to cross the blood-brain barrier means it directly affects the central nervous system. Patients should not drive, operate complex machinery, or engage in hazardous activities until they are fully aware of how carbinoxamine affects them. Combining this drug with other sedatives or alcohol significantly compounds this risk.
Alcohol consumption is strictly discouraged while taking carbinoxamine. Alcohol acts as a CNS depressant and has a synergistic effect with carbinoxamine, meaning the combination is much more sedating than either substance alone. This can lead to dangerous levels of respiratory depression, extreme lack of coordination, and increased risk of accidents.
While carbinoxamine is not typically associated with a severe withdrawal syndrome, stopping the medication abruptly after long-term use may result in a 'rebound' effect where allergy symptoms return with increased intensity. If a patient has been taking the drug daily for several weeks, a healthcare provider may suggest a gradual taper to avoid discomfort. There is no known risk of physical addiction, but psychological dependence on the sedative effects can occur in some individuals.
> Important: Discuss all your medical conditions, especially any history of glaucoma, prostate issues, or breathing problems, with your healthcare provider before starting Carbinoxamine.
Monoamine Oxidase Inhibitors (MAOIs): Carbinoxamine should never be used concurrently with MAOIs (such as phenelzine, selegiline, or tranylcypromine) or within 14 days of stopping an MAOI. MAOIs prolong and intensify the anticholinergic (drying) effects of antihistamines. This combination can lead to severe hypertension, high fever, and potentially fatal anticholinergic toxicity.
Carbinoxamine can interfere with the results of skin allergy tests. Because the drug blocks the H1 receptors, it will prevent the 'wheal and flare' reaction that allergists look for when testing for sensitivities. Patients are typically advised to stop taking carbinoxamine at least 4 to 7 days before undergoing skin testing. It may also occasionally cause false-positive results on certain urine drug screens for methadone or other opioids, depending on the specific assay used.
For each major interaction, the mechanism usually involves either pharmacodynamic synergy (both drugs doing the same thing to the body) or pharmacokinetic interference (one drug changing how the other is moved or broken down). Management strategies usually involve avoiding the combination or adjusting the dose under strict medical supervision.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including over-the-counter cold and flu medicines which may also contain antihistamines.
Carbinoxamine must NEVER be used in the following circumstances:
In these conditions, a healthcare provider must perform a careful risk-benefit analysis before prescribing carbinoxamine:
Patients who have had a severe reaction to other ethanolamine antihistamines (such as diphenhydramine, clemastine, or dimenhydrinate) are highly likely to be cross-sensitive to carbinoxamine. This means their immune system recognizes the similar chemical structure and may trigger an allergic response. If you have ever had hives, swelling, or breathing trouble after taking Benadryl, you must inform your doctor before taking carbinoxamine.
> Important: Your healthcare provider will evaluate your complete medical history, including any underlying chronic conditions, before determining if Carbinoxamine is a safe option for you.
Carbinoxamine is classified under the older FDA Pregnancy Category C. This means that animal reproduction studies have shown an adverse effect on the fetus, or there are no adequate and well-controlled studies in humans. It is not known whether carbinoxamine can cause fetal harm when administered to a pregnant woman or if it can affect reproduction capacity. Therefore, carbinoxamine should be used during pregnancy only if the potential benefit clearly outweighs the potential risk to the fetus. Use during the third trimester is particularly scrutinized as newborns may be more sensitive to the effects of antihistamines if the drug is in their system at birth.
Carbinoxamine is contraindicated in nursing mothers. First-generation antihistamines are known to be excreted in human milk and can inhibit lactation by decreasing serum prolactin levels. More importantly, infants, especially neonates, have a higher risk of experiencing adverse reactions to antihistamines, including unusual excitement, irritability, or dangerous respiratory depression. If antihistamine therapy is essential for the mother, healthcare providers usually recommend second-generation agents that have better safety data for breastfeeding or advise the cessation of nursing.
Carbinoxamine is strictly contraindicated in children under 2 years of age. In children older than 2, it must be used with caution and precise dosing. Pediatric patients may be more sensitive to the anticholinergic effects and are more likely to experience 'paradoxical excitation,' characterized by hallucinations, tremors, and insomnia, rather than the expected sedation. Growth effects have not been specifically linked to carbinoxamine, but long-term use in children is generally avoided.
Clinical studies of carbinoxamine did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. However, clinical experience has shown that elderly patients are significantly more likely to experience dizziness, sedation, and hypotension. The risk of confusion and falls is a major concern. Furthermore, the higher prevalence of renal and hepatic impairment in this population means the drug may stay in their system longer, increasing the risk of toxicity. Most geriatric specialists recommend avoiding carbinoxamine in favor of non-sedating antihistamines.
In patients with decreased kidney function (low GFR), the clearance of carbinoxamine and its metabolites is reduced. While there is no standard formula for dose reduction, providers often increase the interval between doses (e.g., from every 6 hours to every 12 hours). There is insufficient data on whether carbinoxamine is cleared by hemodialysis or peritoneal dialysis.
Because the liver is the primary site of metabolism for carbinoxamine, patients with Child-Pugh Class B or C hepatic impairment should be started on the lowest possible dose. Monitoring for signs of 'anticholinergic load,' such as extreme confusion or dry skin, is essential in these patients.
> Important: Special populations require individualized medical assessment. Always disclose your full health status, including pregnancy or nursing status, to your medical team.
Carbinoxamine maleate is an H1-receptor antagonist. Its primary molecular mechanism involves competitive binding to the H1 receptors located on the surface of effector cells. Unlike histamine, which activates these receptors to trigger inflammatory cascades, carbinoxamine binds to the receptor in an inactive conformation, effectively 'locking' it and preventing histamine from binding. This inhibits histamine-induced vasodilation, increased capillary permeability, and constriction of smooth muscle in the respiratory and gastrointestinal tracts. Additionally, carbinoxamine has a high affinity for muscarinic acetylcholine receptors, which accounts for its significant anticholinergic effects, such as reducing secretions in the upper airway.
The onset of action for carbinoxamine is relatively rapid, typically occurring within 15 to 30 minutes of oral administration. Peak therapeutic effects are usually seen within 1 to 2 hours. The duration of effect lasts between 4 and 6 hours for immediate-release forms, and up to 12 hours for extended-release formulations. Tolerance to the sedative effects may develop after several days of continuous use, but the antihistaminic effect usually remains consistent.
| Parameter | Value |
|---|---|
| Bioavailability | High (Rapidly absorbed) |
| Protein Binding | Approximately 70-80% |
| Half-life | 10 - 20 hours |
| Tmax | 1.5 - 2 hours |
| Metabolism | Hepatic (Extensive) |
| Excretion | Renal (>90% as metabolites) |
Carbinoxamine belongs to the ethanolamine class of first-generation antihistamines. It is therapeutically categorized as a systemic H1-antagonist. Related medications in the same class include diphenhydramine (Benadryl), clemastine (Tavist), and dimenhydrinate (Dramamine). It is distinguished from second-generation antihistamines (like fexofenadine) by its ability to cross the blood-brain barrier and its lack of selectivity for peripheral H1 receptors.
Medications containing this ingredient
Common questions about Carbinoxamine
Carbinoxamine is primarily used to relieve symptoms of seasonal and perennial allergic rhinitis, such as sneezing, runny nose, and itchy eyes. It is also effective in treating vasomotor rhinitis and allergic conjunctivitis caused by environmental allergens. Additionally, healthcare providers may prescribe it for mild, uncomplicated skin hives (urticaria) and swelling (angioedema). It works by blocking H1 receptors, which prevents histamine from causing allergic inflammation. Because it is a first-generation antihistamine, it is often used when a 'drying' effect on the nasal passages is desired.
The most common side effect is significant drowsiness or sedation, which affects a large percentage of users. Patients also frequently report dry mouth, nose, and throat due to the drug's anticholinergic properties. Dizziness and a lack of coordination are also common, making tasks like driving potentially dangerous. Some individuals may experience stomach upset or a thickening of mucus in the lungs. In children, it can sometimes cause the opposite effect, leading to nervousness or trouble sleeping.
No, you should strictly avoid alcohol while taking carbinoxamine. Both alcohol and carbinoxamine are central nervous system depressants, and when taken together, they can dangerously increase sedation and respiratory depression. This combination can lead to extreme dizziness, loss of consciousness, and a significantly higher risk of accidents or falls. Even small amounts of alcohol can interact poorly with this medication. Always consult your doctor about the risks of combining any substances with your prescription.
Carbinoxamine is classified as FDA Pregnancy Category C, meaning its safety has not been fully established through controlled human trials. Animal studies have shown some potential for adverse effects, so it should only be used if the benefits to the mother outweigh the potential risks to the fetus. It is especially important to avoid unnecessary use during the third trimester. Most doctors prefer to prescribe second-generation antihistamines with more extensive safety data for pregnant patients. Always discuss your pregnancy status with your healthcare provider before use.
Carbinoxamine works relatively quickly, with most patients feeling relief from allergy symptoms within 15 to 30 minutes of taking a dose. The medication reaches its peak concentration in the bloodstream about 1.5 to 2 hours after administration. For immediate-release tablets or liquids, the effects typically last for about 4 to 6 hours. Extended-release versions are designed to provide relief for up to 12 hours. If you do not feel any improvement after several doses, you should contact your doctor to re-evaluate your treatment plan.
Yes, carbinoxamine can generally be stopped suddenly without dangerous withdrawal symptoms, as it is not physically addictive. However, if you have been taking it daily for a long period, stopping abruptly may cause your allergy symptoms to return quickly and potentially feel more severe. This is known as a rebound effect. If you have concerns about stopping the medication, your doctor can advise you on how to taper off. It is always best to treat the underlying cause of your allergies rather than relying on long-term antihistamine use.
If you miss a dose, take it as soon as you remember, unless it is almost time for your next scheduled dose. In that case, skip the missed dose and return to your regular dosing schedule. You should never take two doses at once to 'catch up,' as this increases the risk of toxic side effects like extreme lethargy or heart palpitations. Setting a daily alarm can help you stay on track with your medication. If you frequently miss doses, discuss a more convenient dosing schedule with your healthcare provider.
Weight gain is not a commonly reported side effect of carbinoxamine in short-term clinical studies. However, some first-generation antihistamines are known to potentially increase appetite or cause lethargy, which could indirectly lead to weight changes over long periods of time. If you notice significant or rapid weight gain while taking this medication, it is important to discuss it with your doctor. They can help determine if the drug or another underlying factor is responsible. Maintaining a balanced diet and regular activity can help mitigate these potential effects.
Carbinoxamine has several significant drug interactions, particularly with other drugs that cause sleepiness or dry mouth. It should never be taken with MAO inhibitors, and you should be very careful when taking it with opioids, sleep aids, or muscle relaxants. Even over-the-counter cold medicines may contain other antihistamines, leading to an accidental overdose. Always provide your doctor and pharmacist with a full list of all medications and supplements you are using. They can check for potential interactions that might make the medication unsafe for you.
Yes, carbinoxamine maleate is available as a generic medication in both tablet and oral solution forms. Generic versions are typically more cost-effective than brand-name versions like Karbinal ER or Palgic. The FDA requires generic medications to have the same active ingredient, strength, and effectiveness as the brand-name versions. However, inactive ingredients like dyes or flavorings may differ between manufacturers. Check with your pharmacist to see which version is covered by your insurance plan.