Uses and Contraindications of Loratadine

12 January, 2021
Loratadine is a drug that interacts with histamine H1 receptors. Specifically, it competes with histamine and binds to it.

Loratadine is an active H-1 antihistamine drug used for treating allergy symptoms. Its route of administration is mainly oral. Unlike other antihistamine drugs, such as astemizole or terfenadine, this drug doesn’t have a sedative effect.

This is due to its small penetration into the central nervous system. Also, it has a small affinity to the H-1 receptors in this part of the body. Furthermore, the drug doesn’t cause ventricular tachycardias.

Physicians usually prescribe this antihistamine along with pseudoephedrine, a decongestant useful in the treatment of colds and allergic symptoms.

In this respect, loratadine can relieve the symptoms of chronic urticaria and other skin allergies. Also, it’s appropriate for allergic rhinitis symptoms such as sneezing, runny nose, and itching.

Moreover, it helps relieve allergic conjunctivitis and its symptoms such as tearing and itching eyes.

What triggers allergic symptoms?

A woman blowing her nose.

An allergy is an exaggerated body reaction to particles or substances that are harmless to most proteins. The substances people are allergic to are known as “allergens,” and the symptoms as “allergic reactions.”

The immune system of an allergic person responds by producing many antibodies to a given allergen when it enters the body. These defenses are innate.

You may already know that antibodies are protein molecules in charge to attack any strange substance that enters the organism.

The antibody sends chemical mediators after exposure to an allergen and thus, cause the typical symptoms of an allergic reaction

Among them:

  • Skin inflammation, itching, and rashes
  • Red eyes and tearing
  • Sneezing, coughing, and itchy throat
  • Skin and respiratory lesions, and even vomiting

Learn about the Types of Chronic Urticaria and Their Characteristics

How does loratadine affect the body?

A bottle of loratadine.

As we have said, loratadine is a drug that interacts with histamine H1 receptor antagonists. Specifically, it competes with histamine for binding to these receptors.

Also, it’s a competitive blocker that keeps histamine from binding to its receptor. Thus, it hinders the effects of histamine on receptors in the digestive tract, uterus, large vessels, and bronchial muscles.

H1-antagonists have several properties they share with anticholinergics, antispasmodic, ganglionic, and adrenergic blockers.

However, loratadine is basically devoid of anticholinergic effects. In fact, in-vitro studies revealed this drug has a weak affinity for cholinergic and alpha-adrenergic receptors.

Read about Betahistine – Indications and Precautions

Contraindications for loratadine

A doctor explaining loratadine to a patient.

Obviously, people who have known hypersensitivity to this drug should stay away from it. This is because the small anticholinergic activity of H1 antihistamines may thicken bronchial secretions.

Also, it could worsen acute asthma attacks. However, this anticholinergic activity doesn’t exclude the use of antihistamines in asthma patients. Particularly when using drugs such as loratadine with a minimal anticholinergic component.

Also, loratadine may cause drowsiness and sleepiness in some patients. This is why informing patients treated with this drug about the danger of driving or operating heavy machinery is essential.

Also, note that the safety and effectiveness of this drug in children under 2 years of age are still under review. Thus, doctors shouldn’t prescribe it to them.

Moreover, breastfeeding women should avoid consumption of loratadine as it’s partly excreted through breast milk.

Loratadine is widely used against allergies

This drug’s main mode of action is to interact with histamine H1 receptors and keep histamine from binding to them.

Also, it doesn’t cause drowsiness in the people who use it. However, there are contraindications in some situations due to certain complications it could trigger.

Ask your doctor or pharmacist any questions you may have about loratadine treatment. Finally, don’t hesitate to tell them about any side effects you may experience after its intake.

  • Aguilar, A. G. (1996). Antihistamínicos. Revista Alergia Mexico.
  • Álvarez Navascués, R., Bastardo, Z., Fernández Díaz, M., Guerediaga, J., Quiñones, L., & Pinto, J. (2003). Loratadina y nefritis intersticial aguda. Nefrologia.
  • Gomez, C. (2003). Los antihistamínicos y sus usos. Cimed.