Loratadine

For adults and children aged 12 years and older, the standard recommended dose of Loratadine is 10 mg taken orally once daily. This dose is sufficient to provide 24-hour relief from symptoms of allergic rhinitis or chronic urticaria. It is important not to exceed the 10 mg limit in a 24-hour period unless specifically directed by a healthcare provider, as higher doses do not necessarily increase efficacy but do increase the risk of somnolence (drowsiness).

Loratadine is approved for use in children as young as 2 years old. The dosage is strictly based on age:

• Children 6 years and older: The recommended dose is 10 mg (one tablet or 10 mL of syrup) once daily.
• Children 2 to 5 years of age: The recommended dose is 5 mg (5 mL of syrup or one 5 mg chewable/ODT) once daily.
• Children under 2 years of age: The safety and effectiveness of Loratadine have not been established for this age group. Use in infants and toddlers under 2 should only occur under the direct supervision of a pediatrician.

Renal Impairment

In patients with significant renal insufficiency (kidney dysfunction), the clearance of Loratadine and its metabolites is reduced. For adults and children 6 years of age and older with a glomerular filtration rate (GFR) or creatinine clearance of less than 30 mL/min, the starting dose should be 10 mg every other day. For children 2 to 5 years of age with renal impairment, the starting dose should be 5 mg every other day.

Hepatic Impairment

Because Loratadine is extensively metabolized by the liver, patients with hepatic failure or significant liver disease require dosage adjustments. Similar to the renal protocol, adults and children 6 years and older with liver impairment should start with 10 mg every other day. Children 2 to 5 years old should start with 5 mg every other day.

Elderly Patients

While no specific dose adjustment is required for healthy elderly patients, healthcare providers should be mindful that older adults are more likely to have decreased renal or hepatic function. Clinical monitoring is advised to ensure the 10 mg daily dose is well-tolerated without excessive sedation or anticholinergic-like effects.

Loratadine can be taken with or without food. If you find that the medication causes stomach upset, taking it with a meal or a glass of milk may help.

• Standard Tablets: Swallow the tablet whole with a full glass of water. Do not crush or chew the 10 mg tablets unless they are specifically labeled as chewable.
• Orally Disintegrating Tablets (ODTs): Ensure your hands are dry before handling the tablet. Place the tablet on your tongue and allow it to dissolve completely; it can be swallowed with or without water. Use the tablet immediately after opening the blister pack.
• Oral Solution: Use a calibrated measuring device (oral syringe or dosing cup) to ensure the correct dose. Do not use a household teaspoon, as it is not an accurate measurement tool.
• Storage: Store Loratadine at room temperature, between 68°F and 77°F (20°C to 25°C), away from excessive moisture and heat.

If you miss a dose, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at once to make up for a missed one, as this increases the risk of side effects.

Symptoms of a Loratadine overdose may include tachycardia (rapid heartbeat), somnolence (extreme sleepiness), headache, and extrapyramidal symptoms (uncontrolled muscle movements). In the event of a suspected overdose, contact your local poison control center or seek emergency medical attention immediately. Treatment is generally supportive and symptomatic; gastric lavage (stomach pumping) may be considered if performed shortly after ingestion.

> Important: Follow your healthcare provider's dosing instructions precisely. Do not adjust your dose or frequency without professional medical guidance.

Loratadine is generally very well-tolerated, and many patients experience no side effects at all. However, some individuals may experience mild reactions. The most frequently reported common side effect is:

• Headache: This is the most common complaint, occurring in approximately 12% of patients in clinical trials. It is usually mild and transient, often resolving as the body adjusts to the medication.
• Somnolence (Drowsiness): Although marketed as non-drowsy, roughly 8% of people taking 10 mg may feel slightly sleepy. This is significantly lower than the sedation rates seen with first-generation antihistamines like Benadryl (diphenhydramine).

These effects occur in a smaller percentage of the population (approximately 2% to 5%):

• Dry Mouth (Xerostomia): A feeling of dryness in the mouth or throat due to mild anticholinergic activity.
• Fatigue: A general feeling of tiredness or lack of energy.
• Nervousness: Some patients, particularly children, may experience mild restlessness or anxiety.
• Abdominal Pain: Mild stomach discomfort or nausea.
• Hyperkinesia: Excessive muscle activity or restlessness, more commonly observed in pediatric patients.

Rare side effects are those that occur in less than 1% of the population but have been documented in post-marketing surveillance:

• Tachycardia and Palpitations: A sensation of a racing or fluttering heart.
• Syncope: Fainting or temporary loss of consciousness.
• Hepatic Function Abnormalities: Rare cases of jaundice (yellowing of the skin/eyes), hepatitis, or elevated liver enzymes.
• Alopecia: Temporary thinning or loss of hair.
• Erythema Multiforme: A rare skin reaction characterized by target-shaped lesions.

While extremely rare, serious allergic reactions can occur. You must seek emergency help if you experience:

• Anaphylaxis: A severe, life-threatening allergic reaction. Symptoms include difficulty breathing, swelling of the face, lips, tongue, or throat, and a sudden drop in blood pressure.
• Angioedema: Severe swelling beneath the surface of the skin, often around the eyes or mouth.
• Seizures: Any new onset of seizure activity while taking this medication requires immediate evaluation.
• Severe Dizziness: Feeling as though you might pass out or lose balance entirely.

> Warning: Stop taking Loratadine and call your doctor immediately if you experience any of these serious symptoms.

Loratadine is considered safe for long-term use when taken as directed. Unlike some other classes of medications, there is no evidence that Loratadine causes significant physical dependence or withdrawal symptoms upon discontinuation. However, chronic use should be periodically reviewed by a healthcare provider to ensure that the underlying allergy is being managed appropriately and that no rare systemic effects (such as liver enzyme elevations) are developing. Some patients may report a perceived "tolerance" where the drug seems less effective over time, though clinical studies generally do not support the development of pharmacological tolerance to H1 antagonists.

There are currently no FDA Black Box Warnings for Loratadine. It has a high safety margin and is widely used across various demographics. However, the lack of a black box warning does not mean the drug is without risk; patients must still adhere to the recommended dosing and precautions.

Report any unusual or persistent symptoms to your healthcare provider to ensure the continued safe use of this medication.

Loratadine is an over-the-counter medication, but it must be used with caution in certain populations. The most important safety consideration is ensuring the correct diagnosis. Symptoms that mimic allergies, such as a persistent cough or shortness of breath, may actually be signs of asthma or other respiratory conditions that Loratadine cannot treat. Additionally, patients with phenylketonuria (PKU) must be aware that some orally disintegrating tablet (ODT) formulations contain aspartame, which is a source of phenylalanine.

No FDA black box warnings for Loratadine. It is recognized as having a favorable safety profile when used according to the label instructions.

• Allergic Reactions / Anaphylaxis Risk: While Loratadine treats allergies, it is possible to be allergic to the drug itself or its inactive ingredients (such as lactose or corn starch). If you develop hives, a rash, or swelling after taking Loratadine, discontinue use immediately.
• Hepatotoxicity: Although rare, Loratadine is processed by the liver. Patients with pre-existing liver disease (cirrhosis, hepatitis) are at a higher risk for drug accumulation and potential toxicity. Close monitoring of liver function tests (LFTs) may be required in these patients.
• Nephrotoxicity: Patients with severe renal impairment (kidney failure) may experience reduced clearance of the drug, leading to higher plasma levels and an increased risk of side effects like sedation and dry mouth.
• Central Nervous System (CNS) Effects: While Loratadine is non-sedating for most, individuals react differently. Caution should be exercised when first starting the drug to see how it affects your alertness.

For the average healthy individual taking Loratadine OTC, routine laboratory monitoring is not typically required. However, for specific groups:

• Liver/Kidney Patients: Periodic blood tests to check creatinine levels and liver enzymes may be necessary to adjust the dose.
• Allergy Testing: Loratadine can interfere with the results of skin prick tests used to diagnose allergies. You should stop taking Loratadine at least 48 to 72 hours before undergoing any allergy skin testing to avoid false-negative results.

At the recommended dose of 10 mg, Loratadine is generally considered non-sedating. However, clinical trials have shown that a small percentage of users may experience somnolence. Until you are certain how Loratadine affects you, use caution when driving a car, operating heavy machinery, or performing tasks that require full mental alertness. This is especially important if you are taking other medications that can cause drowsiness.

While Loratadine does not significantly potentiate (increase) the effects of alcohol in the same way that first-generation antihistamines do, it is still advisable to limit alcohol consumption while taking any medication that affects the CNS. Combining alcohol with Loratadine may increase the risk of dizziness or impaired coordination in sensitive individuals.

Loratadine can be stopped abruptly without the need for a tapering schedule. There is no known withdrawal syndrome associated with the cessation of Loratadine. If symptoms return after stopping the medication, consult your doctor about alternative long-term management strategies for your allergies.

> Important: Discuss all your medical conditions, especially liver or kidney disease, with your healthcare provider before starting Loratadine.

There are no absolute "do not use" contraindications for Loratadine involving other drugs that lead to fatal outcomes. However, it should not be used in combination with Desloratadine (Clarinex), as desloratadine is the primary active metabolite of Loratadine. Taking both simultaneously is essentially a double dose and significantly increases the risk of toxicity and side effects.

• Amiodarone: This anti-arrhythmic medication may increase the plasma concentration of Loratadine, potentially increasing the risk of side effects. Monitor for signs of excessive sedation or heart rate changes.
• CNS Depressants: While Loratadine is non-sedating, combining it with other CNS depressants (such as benzodiazepines, opioids, or sleep medications) can have an additive effect on drowsiness in some patients.

Several drugs that inhibit the cytochrome P450 3A4 (CYP3A4) or 2D6 (CYP2D6) enzymes can increase the levels of Loratadine in the blood. These include:

• Ketoconazole and Itraconazole: Antifungal medications that significantly increase Loratadine concentrations (up to 300% increase in AUC). While this rarely leads to clinical toxicity, patients should be monitored for increased side effects.
• Erythromycin and Clarithromycin: Macrolide antibiotics that also inhibit CYP3A4, leading to higher Loratadine levels.
• Cimetidine: A medication used for heartburn that can increase Loratadine plasma concentrations by inhibiting its metabolism.

In most cases, these interactions do not require a dose change but do require awareness of potential side effects like dry mouth or headache.

• High-Fat Meals: Consuming a high-fat meal before taking Loratadine can delay the time it takes to reach peak concentration (Tmax) and may increase the total absorption (AUC). For the most consistent results, it is best to take the medication at the same time each day relative to food intake.
• Grapefruit Juice: Unlike some other medications, grapefruit juice does not have a clinically significant effect on the metabolism of Loratadine, though some studies suggest a minor delay in absorption.

• St. John's Wort: This herbal supplement is a potent inducer of CYP3A4. It may speed up the metabolism of Loratadine, potentially reducing its effectiveness in controlling allergy symptoms.
• Kava Kava / Valerian Root: These supplements have sedative properties. Combining them with Loratadine may increase the likelihood of feeling drowsy.

• Skin Prick Tests: As mentioned, Loratadine suppresses the wheal and flare reaction to allergen extracts. To ensure accurate results in allergy testing, the medication must be discontinued at least 3 days prior to the procedure.

For each interaction, the primary mechanism is usually the inhibition or induction of the liver enzymes responsible for breaking down the drug. The clinical consequence is typically an increase in the duration or intensity of side effects rather than a dangerous toxic reaction.

> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including those purchased without a prescription.

There are very few absolute contraindications for Loratadine, but they are critical for patient safety:

• Hypersensitivity to Loratadine: If you have previously had an allergic reaction to Loratadine or any of the inactive ingredients in the formulation (such as lactose, starch, or magnesium stearate), you must not take this medication. Reactions can range from mild rashes to life-threatening anaphylaxis.
• Hypersensitivity to Desloratadine: Because desloratadine is the active metabolite of Loratadine, patients who are allergic to Clarinex (desloratadine) will also be allergic to Loratadine.

Relative contraindications require a healthcare provider to weigh the benefits against the potential risks:

• Severe Hepatic Impairment: In patients with end-stage liver disease, the body cannot effectively clear the drug. While not strictly forbidden, the dose must be reduced (usually to every other day) and the patient monitored closely for signs of CNS depression.
• Severe Renal Insufficiency: Patients with a GFR below 30 mL/min require dose adjustment. Without adjustment, the risk of side effects increases significantly due to the accumulation of the active metabolite, desloratadine.
• Asthma: While Loratadine is not contraindicated in patients with asthma, it should not be used as a treatment for acute asthma attacks. It does not provide bronchodilation and cannot replace rescue inhalers like albuterol.

Patients who have demonstrated sensitivity to other piperidine antihistamines (such as azatadine or cyproheptadine) should use Loratadine with caution, as there is a theoretical risk of cross-reactivity due to similar chemical structures. If you have had a severe reaction to any antihistamine in the past, consult an allergist before starting Loratadine.

> Important: Your healthcare provider will evaluate your complete medical history, including any previous drug allergies, before determining if Loratadine is a safe option for you.

Loratadine was previously classified as FDA Pregnancy Category B. This means that animal reproduction studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women. Large-scale observational studies and registries have generally not shown an increased risk of congenital malformations (birth defects) in humans when Loratadine is used during pregnancy. However, because no drug is 100% risk-free, it should only be used during pregnancy if clearly needed and under the guidance of an obstetrician.

Loratadine and its metabolite, desloratadine, are excreted into breast milk. However, the amount transferred to the infant is very small (estimated at less than 1% of the maternal weight-adjusted dose). The American Academy of Pediatrics considers Loratadine to be generally compatible with breastfeeding. One potential concern is that antihistamines can theoretically decrease serum prolactin levels, which might interfere with milk production, though this is rarely reported with second-generation antihistamines like Loratadine.

Loratadine is safe and effective for children aged 2 years and older. It is a preferred choice for pediatric allergies because it does not cause the cognitive impairment or hyperactivity often seen with older antihistamines. It is NOT approved for use in children under 2 years of age without a doctor's specific order. Parents should be aware that in some children, Loratadine may cause paradoxical excitation (feeling "wired" or hyperactive) rather than sedation.

Clinical studies of Loratadine did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently than younger subjects. However, because elderly patients are more likely to have decreased renal and hepatic function, they are at a higher risk for drug accumulation. Furthermore, the elderly are more susceptible to the anticholinergic-like side effects of antihistamines, such as confusion, dizziness, and urinary retention. A starting dose of 10 mg every other day may be prudent for frail elderly patients.

In patients with chronic kidney disease (CKD), the half-life of Loratadine and desloratadine is prolonged. For those with a creatinine clearance < 30 mL/min, the standard 10 mg dose should be taken every other day. Loratadine is not significantly removed by hemodialysis; therefore, supplemental doses after dialysis are not necessary.

In patients with chronic alcoholic liver disease, the elimination half-life of Loratadine can double. For patients with significant hepatic impairment (Child-Pugh Class B or C), the frequency of dosing should be reduced to 10 mg every other day to prevent systemic accumulation and associated side effects.

> Important: Special populations require individualized medical assessment to ensure the safest and most effective use of Loratadine.

Loratadine is a potent, long-acting tricyclic antihistamine with selective peripheral H1-receptor antagonistic activity. It functions as an inverse agonist, meaning it binds to the H1 receptor and stabilizes it in its inactive state, thereby preventing histamine from binding and exerting its pro-inflammatory effects. Its chemical structure (a piperidine derivative) gives it a high affinity for peripheral receptors and a low affinity for the cholinergic and alpha-adrenergic receptors, which explains its lack of traditional side effects like blurred vision or significant heart rate changes. Its inability to cross the blood-brain barrier is a result of its low lipophilicity and its recognition by the P-glycoprotein efflux transporter.

Following oral administration, the antihistaminic effects of Loratadine begin within 1 to 3 hours, reach a maximum at 8 to 12 hours, and persist for more than 24 hours. There is no evidence of the development of tolerance (tachyphylaxis) to the effects of Loratadine even after 28 days of continuous dosing. It does not cause significant QTc interval prolongation, a dangerous heart rhythm issue associated with some older second-generation antihistamines like terfenadine.

| Parameter | Value |

|---|---|

| Bioavailability | Increased 40% with food |

| Protein Binding | 97% to 99% (Loratadine) |

| Half-life | 8.4 hours (Parent), 28 hours (Metabolite) |

| Tmax | 1 to 1.5 hours |

| Metabolism | Hepatic (CYP3A4, CYP2D6) |

| Excretion | Renal 40%, Fecal 40% |

• Molecular Formula: C22H23ClN2O2
• Molecular Weight: 382.88 g/mol
• Solubility: Insoluble in water; very soluble in acetone, alcohol, and chloroform.
• Description: A white to off-white powder that is a derivative of azatadine.

Loratadine is classified as a second-generation H1-receptor antagonist. It belongs to the piperidine subclass of antihistamines. Related medications in this class include fexofenadine (Allegra), cetirizine (Zyrtec), and its own active metabolite, desloratadine (Clarinex). Second-generation antihistamines are the standard of care for allergic rhinitis due to their superior safety profile compared to first-generation agents.