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Loratadine (Claritin) - Uses, Dosage, Side Effects, Drug Warnings, and Precautions

Published on Feb 24, 2022 and last reviewed on Jul 04, 2022   -  17 min read


Loratadine (Claritin) is a drug used to relieve symptoms of allergies such as sneezing, runny nose, redness, or itchy eyes, nose, or throat, etc. Learn about its uses, dosage, drug warnings, side effects, precautions, drug interactions, and more.

Loratadine (Claritin) - Uses, Dosage, Side Effects, Drug Warnings, and Precautions


Loratadine (Claritin) is an over-the-counter medicine used to relieve the symptoms of hay fever (allergy to dust, pollen, or other substances in the air), upper respiratory tract allergies, and other allergies such as sneezing, itching, watery eyes, and runny nose. It can also be used to relieve itching from hives. However, Loratadine does not prevent hives or treat severe allergic reactions like anaphylaxis. The drug Loratadine in the form of tablets or capsules should not be used in children under six years of age. Whereas in cases of liquid or chewable tablets, it should not be used in children under two years of age without a doctor's advice

Loratadine is an antihistamine and is also available in combination with Pseudoephedrine (Sudafed, others). The monograph always includes only the information on Loratadine, so if you are taking a combination product (Loratadine and Pseudoephedrine), read the details mentioned on the package label, or you can ask the physician or pharmacist for more information.

Drug Group:

Loratadine (Claritin) belongs to the class of drugs called antihistamines. Antihistamines work by blocking or reducing the effects of the natural chemical histamine, which is a substance in the body that causes allergic symptoms of sneezing, itching, watery eyes, runny nose, etc.

What Is Loratadine Used For?

Usage of Loratadine: The drug can be used as an over-the-counter drug to self-treat some allergic symptoms but the directions on the product packaging should be read properly before that. If the doctor has prescribed the drug, it is important to follow all the instructions given by the doctor.

Loratadine is used in the treatment of the following conditions-

1. Hay Fever or Allergic Rhinitis - A type of inflammation in the nose, and Loratadine is used to relieve nasal and non-nasal symptoms that occur when the immune system overreacts to allergens in the air.

2. Urticaria - Otherwise called hives that cause red, itchy welts due to a skin reaction. It is considered chronic hives if the welts persist for more than six weeks. Loratadine is used to treat skin hives and itching in people with chronic skin reactions.

3. Physical Urticaria - A condition in which allergic skin rashes (red allergic skin lesions and pruritus) are produced by,

4. Serious Allergic Reaction (Anaphylaxis) - It is a potentially life-threatening allergic reaction, which could occur within seconds or minutes of exposure to something you are allergic to.

5. Upper Respiratory Allergies -


What Is Allergic Rhinitis?

Allergic rhinitis is an allergic reaction to allergens such as pollen grains (the most common one). It is also known as hay fever. It is studied that almost 30 % of the world population may have allergic rhinitis. Other than pollen the allergens are dust mites, animal dander, cat saliva, or molds.

The Common Symptoms of the Disease Are:

What Are the Types of Allergic Rhinitis?

There are two types of allergic rhinitis, which are seasonal and perennial.

What Factors Can Trigger Allergic Rhinitis?

Lifestyle Changes to Avoid Hay Fever:

There are some important points that should be kept in mind to prevent Hay fever in day-to-day life:

1. While Outside the House:

2. While Inside the House:

For Patients:

Before Taking the Drug:

How Does Loratadine Work?

Histamine is a natural chemical substance of the body that causes symptoms of allergy. Mast cells are histamine-storing cells, and they release histamine to attach to other cells with receptors for histamine on their surfaces. This released histamine starts stimulating the cells to release chemicals that are associated with allergy, including hives, itching, and redness.

Loratadine is an FDA-approved long-acting drug that is used for the treatment of allergies as it blocks the H1 type of histamine receptor and it prevents cell activation with H1 receptors by histamine. Unlike some other antihistamines, Loratadine is a non-sedating drug that does not enter the brain from the blood. Therefore, it does not cause drowsiness when taken at recommended doses.

Onset Of Action:

The time required for Loratadine to start acting varies until the person is recommended with daily dosing. It generally starts working within 1 to 3 hours and reaches its peak at approximately after 8 to 12 hours of taking the drug. The duration of action is at least 24 hours, so it is meant to be taken once a day.

Expiry Date:

Avoid taking this medicine after it expires. The listed expiration dates for over-the-counter medicines like Loratadine (Claritin) is typically around two and a half years after manufacturing, or you can verify the expiry date printed on the back of the pack before taking medicine.

Information to Be Given to the Doctor: Before starting the drug, it is essential to inform the doctor about a few important points:

Pregnancy or Breastfeeding: Inform the doctor about any of the two conditions before starting the drug.

What Is the Dosage of Loratadine?

Loratadine is available in the following preparations.

<Preparations and Doses

Loratadine Usual Dosage for Adults

Loratadine Usual Dosage for Children

How to Use Loratadine?

On taking an oral rapidly disintegrating tablet-

  1. Before removing the tablet from the blister package, study the package directions to follow it.

  2. Do not break the tablet.

  3. Do not push the tablet through the foil, as you can damage the tablet.

  4. After the tablet is removed from the blister package, immediately place it on the tongue and close the mouth.

  5. The tablet gets dissolved quickly and can be swallowed with or without water.

Do not use Loratadine to treat bruised hives that are of unusual color and do not itch. It is better to consult a doctor if hives do not improve within three days of treatment or if it lasts for more than 6 weeks.

If you develop any of the following symptoms on taking Loratadine to treat hives, get emergency medical help-

  1. Difficulty swallowing.

  2. Difficulty speaking.

  3. Loss of consciousness.

  4. Drooling.

  5. Swelling of the tongue.

  6. Dizziness.

  7. Swelling in and around the mouth.

  8. Wheezing.

The above-mentioned are symptoms of anaphylaxis which is a life-threatening allergic reaction. If the doctor suspects these symptoms, then he may prescribe an Epinephrine injector (EpiPen).

How to Cope With Side Effects of Loratadine?

Loratadine produces some side effects which need to be handled as the drug is necessary for the suppression of allergic effects. Some of the symptoms are-

Missed Dose:

It is important to take the missed dose as soon as you remember it, but if it is almost time for the next dose, you can skip the missed dose and start continuing with the regular dosing schedule. In order to compensate for a missed one, do not take a double dose.

What Are the Drug Precautions?

1. Do not alter the dosage by yourself; only a doctor can determine if your dose needs to be altered.

2. Do not take more than the recommended amount while using this product because taking more than the recommended amount may cause drowsiness.

3. Seek medical help right away when you become allergic to this medication.

4. If pregnant or planning to get pregnant, ask the doctor before taking the medication.

5. Always tell your physician if you are breastfeeding a baby. It is not expected to harm an unborn baby, but it can pass into breast milk, and it is considered compatible with breastfeeding.

6. Keep it out of children's reach and do not give this medicine to children younger than 2 years old. Before giving a child cough or cold medicine, it is better to ask a doctor. When cough and cold medicines are misused in very young children, it can lead to death.

7. Tell your doctor what medications, vitamins, nutritional supplements, and herbal products you are taking or planning to take.

8. Follow restrictions on food, beverages, or other activities along with the drug when instructed by the doctor.

What if the Drug Loratadine Overdoses?

The symptoms of overdose of Loratadine include drowsiness, headache, and fast or pounding of the heartbeat.

The symptoms of overdose of Loratadine include drowsiness, headache, and fast or pounding of the heartbeat.

Can Two Different Types of Antihistamine Be Consumed Together?

It is not recommended to consume or prescribe two types of antihistamines together as both of them may function differently and may produce different side effects. It is advised to stop one antihistamine before starting the other one.

What Are the Side Effects of Loratadine?

A. Side Effects in Children:

Side Effects on Children Between 2–5 Years of Age Receiving Oral Solution-

Side Effects on Children Between 6–12 Years of Age Receiving Oral Solution-

Side Effects on ≥12 Years of Age Receiving Conventional or Orally Disintegrating Tablets-

B. Side Effects in Adults:

The most common side effects of Loratadine include,

If you come across these symptoms, consult a doctor.

The serious side effects caused by Loratadine are,

If you notice any of these symptoms, stop using the medicine, call your doctor immediately and get medical help right away. All these are not a complete list of side effects, and this drug causes some other side effects.

For the Doctors:


Loratadine is a piperidine histamine H1- receptor antagonist with some anti-allergic properties but does not have sedative effects. Loratadine is approved by the FDA (The United States Food and Drug Administration) to treat and relieve allergic rhinitis (hay fever) and allergic skin known as urticaria. Loratadine is a second-generation antihistamine that is used in a variety of conditions such as watery eyes, runny nose, sneezing, and pruritus. Loratadine can be used as a prescribed medicine or as an over-the-counter drug in both generic and branded forms. The drug can be administered accordingly to children above the age of two, adults, and older patients.


Like all the second-generation antihistamines, Loratadine is selective in nature for peripheral H1 receptors. It does not penetrate through the blood-brain barrier to the central nervous system and also has a poor affinity for CNS H1 receptors. This leads to a lack of CNS depressant quality in the drug and prevents symptoms such as sedation, drowsiness, and impaired psychomotor functions.

Mechanism of Action:

Loratadine is a second-generation, long-acting tricyclic antihistamine that is non-sedating in nature. The drug has selective antagonist properties to peripheral histamine H1 receptors. Loratadine inhibits the H1 receptors which are primarily located on the respiratory smooth muscles, vascular endothelial cells, the gastrointestinal tract, and the immune cells of the body. Unlike the first-generation antihistamines such as Diphenhydramine, Loratadine is a competitive histamine antagonist which does not cross the blood-brain barrier. Hence Loratadine does not affect the brain or neurons of the central nervous system which apparently prevents daytime drowsiness or sedation.

Loratadine binds to different receptors of histamine on the tissues and leads to a decrease in vascular permeability (prevents edema and flushing), decreases the smooth muscle tone (bronchodilation), and decreases the activation of peripheral nociceptive receptors. If the second generation Loratadine is given in higher concentration, it inhibits the histamine release from the mast cells and the basophils which leads to reduction of ICAM-1 expression in epithelial cells and thus inhibits the type 1 hypersensitivity reaction. Loratadine can be called an “inverse agonist” as compared to a histamine antagonist and can reduce the severity of histamine-mediated symptoms in the body. Loranatide possesses a rapid onset of action as it works within 1 hour to 3 hours of administration and reaches its peak effect within 8 hours to 12 hours. The elimination of the drug occurs through both the fecal and renal routes.


Loratadine can be absorbed rapidly and achieves peak plasma concentration within 1 hour to 2 hours and its metabolite achieves peak plasma concentration in 3 hours to 4 hours.

The Volume of Distribution: For Loratadine, the volume of distribution is 120 L/kg.

Protein Binding: Loratadine has a protein binding affinity of up to 97 % to 99 % to the plasma proteins.


Loratadine undergoes first-pass metabolism in the liver and is primarily metabolized by CYP3A4, CYP2D6, CYP1A1, and CYP3A5. CYP3A4 and CYP2D6 are responsible for metabolizing Loratadine to descarboethoxyloratadine. This metabolite of Loratadine is four times more pharmacologically active than Loratadine.

The descarboethoxyloratadine is first glucuronidated by UGT2B10 and then hydroxylated by CYP2C8 to form 3- hydroxy desloratadine. At last, the glucuronidation of 3-hydroxy desloratadine facilitates excretion.

Route of Elimination:

It is observed that over a period of 10 days, 40 % of Loratadine is excreted in the urine and 42 % can be excreted out in the feces. The elimination half-life for Loratadine is approximately 10 hours and for descarboethoxyloratadine, it is 20 hours.


The clearance of loratadine after a single oral dose of 20 mg is 12 L/h/kg and for the 40 mg dose it is 9 L/h/kg. P-glycoprotein is involved in the clearance of many second-generation antihistamines including the Loratadine. P-glycoprotein does not participate in clearing the first-generation antihistamines which helps to explain their adverse effect on the central nervous system. It is noted that antihistamines with more affinity to P-glycoprotein have fewer adverse effects compared to other antihistamines.


Loratadine has very less adverse effects but some of the symptoms reported are drowsiness, insomnia (difficulty in sleeping), headache, fatigue, and rashes. Loratadine overdose can lead to symptoms such as tachycardia, agitation, headache, and drowsiness.

What Are the Interactions of Loratadine?

Prescription drugs, over-the-counter medicines, vitamins, and herbal products can interact with Loratadine (Claritin). It is important to tell the health care professional about all medicines that we take and any medicine you start or stop using. It is always important to look for the following drugs when you take Loratadine as it may cause drug interactions.

The following medications increase the blood concentration of Loratadine (Claritin) by inhibiting the elimination of Loratadine and result in increased adverse events from Loratadine. So, tell your doctor if you are taking any of these medications.

Caution should be taken while taking the following drugs as it reduces blood levels of Loratadine (Claritin).

Clinical Trials for Loratadine:

Objective of the Study: This study was done to determine the efficacy of the onset of action of the two drugs which are used over-the-counter. In this study, the participants underwent sensitization exposure to mountain cedar pollen which helps to create an allergic response.

Number of Participants: 255 participants enrolled in this study.

Allocation: Randomized.

Primary Purpose: The primary purpose of the study is the treatment of the participants.

Clinical Trials for Loratadine

Results: The mean major symptom complex (MSC) helps to evaluate the treatment status of the participants.

Results: the Loratadine was superior to Terfenadine 60 mg and the placebo over the effect on allergic rhinitis.

Loratadine in Pregnancy: Loratadine can be prescribed to pregnant women as there are no adverse effects studied about the drug on the mother or the fetus.

Loratadine in Breastfeeding: Loratadine can be given during breastfeeding if the baby is healthy. It was proposed by the studies that only a very tiny amount of drug passes the breast milk.

Loratadine in Geriatric Patients:The drug is safe to use in the older population as it has no major side effects.

What Are the Common Brands or Trade Names of Loratadine?

The common brandor trade names of Loratadine are,-


Last reviewed at:
04 Jul 2022  -  17 min read




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