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Loratadine: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Dec 30, 2022.

1. How it works

  • Loratadine may be used to treat allergic reactions.
  • Loratadine works selectively on peripheral histamine-1 (H-1) receptors (these are histamine receptors that are located outside of the brain and spinal cord). Because it acts on peripheral histamine receptors, loratadine is much less likely to cause drowsiness compared with some older antihistamines.
  • Histamine is a chemical that is released by mast cells in response to an allergen, and it is responsible for many of the symptoms of an allergic reaction, such as swelling of the mucous membranes, sneezing, and itching. Loratadine binds to histamine receptors and prevents histamine from affecting that receptor, which reduces the symptoms of an allergic reaction.
  • Loratadine belongs to the group of drugs known as antihistamines. Loratadine may also be called an H1-antihistamine, a second-generation antihistamine, or a nonsedating antihistamine.

2. Upsides

  • Used to treat allergic-type reactions due to perennial or seasonal allergic rhinitis (hay fever).
  • Effective at controlling symptoms such as sneezing, itching, watery eyes, and runny nose that occur as a result of other respiratory allergens.
  • Can provide relief from the itching that occurs as a result of chronic urticaria (hives). Symptoms include raised, red, itchy bumps, streaks, or blotches on the skin.
  • May be used in the treatment of other allergic skin disorders.
  • Is less likely to cause sedation than older antihistamines.
  • Can be taken once a day.
  • May be given daily regularly when allergens are most prevalent (such as during spring or summer).
  • Although plasma levels of loratadine may be increased by certain drugs (such as ketoconazole, erythromycin, or cimetidine), this has not resulted in any clinically significant changes.
  • Available over-the-counter.
  • May be considered during pregnancy if the benefits outweigh the risks. A study of 161 women taking loratadine during the first trimester did not show any differences in the rates of miscarriage. Research has not shown an increased risk of any type of birth defect, including hypospadias (a birth defect in boys where the opening of the urethra [the tube that carries urine from the bladder to the outside of the body] is not located at the tip of the penis).
  • Generic loratadine is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • A headache, fatigue, tiredness, or a dry mouth. Side effects are generally uncommon at recommended dosages.
  • Generally does not cause drowsiness; however, some people may be affected so caution should be exercised before driving or operating machinery until the full effects of loratadine are known.
  • The dosage of loratadine should be reduced in people with liver and kidney disease (to an initial dose of 5mg once a day or 10mg every second day).
  • Loratadine, like all other antihistamines, may decrease the response to skin prick tests. Discontinue loratadine at least 48 hours before skin testing.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Loratadine is an antihistamine that effectively treats allergic-type reactions such as hay fever, that is unlikely to cause drowsiness.

5. Tips

  • May be taken with or without food. Loratadine is usually taken once a day. During the pollen season, your doctor may advise you to take it every day if you suffer from seasonal allergic rhinitis.
  • Although loratadine is unlikely to make you drowsy, some people are susceptible to this effect. Do not drive or operate machinery if loratadine makes you drowsy.
  • Seek urgent medical advice if you have hives and develop swelling of the face, throat, or tongue, dizziness, drooling, difficulty speaking, or shortness of breath.
  • Loratadine is not a substitute for epinephrine which is used for the treatment of severe allergies and anaphylaxis.
  • Loratadine is available as a suspension, or as dissolvable or chewable tablets for people who have difficulty swallowing tablets.
  • See your doctor if your mild allergy symptoms have not improved after three days of treatment with loratadine, or if your hives persist for more than six weeks despite taking loratadine.
  • Discontinue loratadine tablets once your allergy symptoms have resolved.
  • Talk to your doctor before taking loratadine during pregnancy or while breastfeeding.

6. Response and effectiveness

  • Loratadine is well absorbed after oral administration and peak levels are reached within an hour. Symptom relief may occur within 10-20 minutes of the first dose, with an average time of onset of 27 minutes. By 45 minutes, all patients should notice a reduction in their allergy symptoms. If not, seek further medical advice.

7. Interactions

Medicines that interact with loratadine may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with loratadine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with loratadine include:

  • amiodarone
  • celecoxib
  • HIV medications such as darunavir, ritonavir, or saquinavir
  • dasatinib
  • diltiazem
  • fluvoxamine
  • mifepristone
  • voriconazole.

Note that this list is not all-inclusive and includes only common medications that may interact with loratadine. You should refer to the prescribing information for loratadine for a complete list of interactions.


Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use loratadine only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2023 Revision date: December 29, 2022.