Desloratadine (oral route)

Grouped in the antihistamine category, desloratadine works to alleviate symptoms that are caused by a compound that our bodies produce called histamine. Histamine causes the symptoms of common allergies including hay fever, hives and food or drink allergies.


Also known by its brand names Clarinex and Clarinex Reditabs, desloratadine is classed as an antihistamine and is used to relieve and reduce the symptoms of common allergies such as hay fever, hives and patient reactions to food, drink or dust mites. Antihistamines act by intercepting the reactions that are caused by a chemical that our bodies produce, known as histamine.

Histamine is a chemical that is made from amino acid and it works by binding to certain proteins in our bodies known as receptors. There are four histamine receptors that cause effects within the body. Histamine will react with different receptors to cause a range of symptoms such as sneezing, a runny nose, irritated and watery eyes and in more serious cases, inflammation and swelling of the mouth, throat and the air passages of the lungs (bronchial tubes). It can also develop a severe itching and swelling of the skin. These symptoms are all the result of common allergic reactions known as hay fever (allergic rhinitis), hives (urticaria) and skin reactions that are mostly caused by food and drink (chronic idiopathic urticaria).

Allergic reactions can be distressing for many patients, causing discomfort and impact on their daily routine. Desloratadine is a medication that will treat common and less severe allergic reactions. It is important that patients do not take this medication in cases that may lead to anaphylaxis, or take this medication long-term and regularly as a way to treat any conditions that may require further medical intervention.

Desloratadine works to quickly alleviate symptoms of allergic reactions, and it can also be taken in the preparation of them, for example on high pollen count days. It is an over-the-counter medication that is only available to patients with a doctor’s prescription and it must never be given to infants and children under the age of four. This can cause serious and potentially life-threatening adverse reactions.

Conditions treated

  • Allergic rhinitis
  • Urticaria
  • Chronic idiopathic urticaria

Type of medicine

  • Antihistamine

Side effects

As with all medications, desloratadine does have the potential to cause unwanted side effects. For this reason, it is important to keep track of any reactions that you may be having. Serious reactions are very rare, but they require immediate treatment and must be alerted to a doctor promptly.

The most common side effect that patients experience when taking desloratadine is a headache. This is a reaction that is likely to disappear once the body becomes adjusted to the medication, but if it concerns you or remains persistent, make sure to discuss it with your doctor.

A dry mouth, nausea, unusual tiredness, drowsiness or weakness and dizziness are less common and less harmful side effects that may go away during treatment. Additionally, patients may experience difficult or painful menstruation (dysmenorrhea), pharyngitis, swollen or painful joints, muscle aches, stiffness or cramps (myalgia) or dyspepsia. These side effects can be more bothersome and should be brought to the attention of your healthcare professional if they cause concern.

In rare and serious cases, patients may experience a fast heartbeat, hives, puffiness or swelling of the eyelids, face or tongue, a shortness of breath, tightness in the chest, wheezing and an abnormal tiredness or weakness. These are all indicators of anaphylaxis, a severe, life-threatening reaction that requires emergency medical attention. Other serious and rare reactions include a shortness of breath or difficulty in breathing (dyspnea), edema, severe itching of the skin (pruritus), a fast, pounding or abnormal heartbeat (tachycardia), and hives or welts. If you experience any of these reactions, it is important that you see a doctor right away.


For the symptomatic relief of allergies including hay fever, hives and food or drink allergies, adults are advised to take one 5mg tablet, once a day. For children who are 12 to 17 years of age, this dose should also be one 5mg tablet, taken daily.

For children from six to 11 years of age, this dose should be 2.5 mg taken once, daily. In children younger than five years of age, the administration of desloratadine will be dependant on the allergic reactions that they may suffer from. Your doctor will need to determine whether the benefits outweigh the risks of the medication, and may advise on an alternative or against taking this medication. If they decide on prescribing a child from one to five years of age with desloratadine, this dose should be 1.25 mg taken once, daily.

If you are taking the disintegrating tablet form of desloratadine, it is important that your hands are dry and that you do not push the tablet through the foil packaging. Instead, you should peel back the foil so that you do not cause damage to the tablet. It is also important to be aware that the tablet will dissolve in seconds. Because of this, you should immediately place it on your tongue and you can swallow it with your saliva. Taking this tablet with water or other drinks is unnecessary.

For patients who will be taking desloratadine in its syrup form, using a calibrated measure dropper or syringe is advised as compared to a teaspoon. This is so that you can ensure that you or your child are given an accurate dose and any risks of side effects or adverse reactions are reduced. If you are unsure of what dose to give your child, please discuss it with your doctor or pharmacist.

If you happen to miss a dose of desloratadine, make sure to take it as soon as possible. However, if enough time has passed that it is almost time for your next dose, it is important that you skip the missed dose and return to your regular dosing schedule.


Before taking this medication, it's important that your doctor is aware of any medical conditions, allergies or sensitivities that you may have. It is also vital that you tell them of any other prescription or over-the-counter medications that you may be taking, as to avoid any adverse reactions.

It is particularly important that doctors are aware of any patients with liver or kidney disease before they begin treatment with desloratadine. This is because the effects of the desloratadine may be increased, as kidney disease will cause a slower removal of the medication from the body.

It is also important to inform your doctor if you have Phenylketonuria (PKU) or if you have a condition that causes slow metabolizers. The disintegrating tablets or desloratadine contain aspartame, which can worsen a patient’s condition of Phenylketonuria.

Additionally, it is essential that you consider diet and lifestyle factors before taking this medication. Alcohol, tobacco and certain foods may all have negative interactions with desloratadine. Make sure to read your medicine documentation thoroughly before beginning your treatment and discuss any queries with your doctor.


Desloratadine can cause some patients to become drowsy, dizzy and less alert than they may normally be. Because of this, it is important that you are aware of how you react to the medication before you take part in any tasks that may require particular focus and attention. This can include driving or operating machinery. If you do notice that you are less alert, tired or dizzy when taking this medication, please do not do any activities that may result in accidents due to these side effects.

It is vital that you do not give this medication to an infant or baby under the age of four years unless you have been instructed by a doctor. Using desloratadine in an infant of this age can cause severe and even life-threatening side effects that will require emergency medical attention.

It also important to remember that patients who are over 65 years of age are more susceptible to kidney or liver conditions. As desloratadine can have adverse reactions to kidney or liver disease, your doctor will want to keep a close eye on patients above this age. It is also important that these patients keep a diligent eye on any side effects or adverse reactions that they may be experiencing.

When it comes to pregnancy and breastfeeding, desloratadine is classified in the pregnancy category C. This means that either animal studies have shown adverse effects to this medication, but there are insufficient studies in pregnant women, or that no animal studies have been conducted and there are inadequate studies in pregnant women. Because of this, it is generally regarded as safe to use in pregnancy. However, if you are pregnant or planning to become pregnant whilst taking desloratadine, it is important that you discuss it with your healthcare professional.

Breastfeeding has also had no adequate studies to prove whether it is unsafe, and is widely regarded as safe to do when taking this medication. However, as with pregnancy, it is important to raise any concerns with your doctor.

Desloratadine is not a long-term medication. If you find that your symptoms do not improve within a few days or if they worsen, please see your doctor.


It is important that you keep desloratadine out of the reach of children, pets and vulnerable adults. It should be stored in a protected container in a cool and dry place such as a cupboard or medicine cabinet. It should also be kept at room temperature, away from direct moisture, heat and light. Never freeze this medication.

With all forms of desloratadine, it is vital that you dispose of it if you believe it has been damaged or tampered with. If you notice irregular particles in the syrup or any damaged packaging, please speak with your doctor or pharmacist. You must always dispose of medication if it has reached its expiry date, or is no longer needed. This will prevent it from getting into the wrong hands or causing harmful reactions.

If you are at all unsure of how to dispose of this medicine, make sure to discuss it with a healthcare professional when possible.


Desloratadine provides patients with convenient and effective relief of bothersome symptoms caused by allergic reactions. Available as an over-the-counter medication, it should always be prescribed by a doctor and will combat symptoms caused by common allergies such as hay fever, hives, dust mites, food and drink.

Allergies such as hay fever and dust mites affect a large proportion of the US population, causing discomfort and impact on many people’s daily routines. The result of histamine, a chemical that our bodies naturally produce, allergy symptoms can include sneezing, irritated and watery eyes, a runny nose and severe itching. In some people, it can also cause a swelling of the bronchial tubes which can be incredibly uncomfortable.

This medication acts to interfere with histamine, working to alleviate the effects that allergic reactions can cause, and stop them from occurring for a period of time. Desloratadine can be taken in the forms of a dissolvable tablet, tablet and syrup, once a day. The fact that it can alleviate symptoms for a single day is ideal for patients who can take it symptomatically, as a preventative measure, or who can take it once any signs of an allergy may arise. It is important that a patient adheres to their doctor's instructions or medicine's documentation, however, as double dosing or taking more than the necessary amount can result in serious and harmful side effects.

The fact that desloratadine has the option to be taken in a variety of oral dosage forms, gives patients a convenient and easy way to administer their medicine. The disintegrating tablets will dissolve in seconds once taken, making them particularly ideal for people on the go, or who may struggle taking other forms of oral tablets. However, because of its fast dissolve time, it is essential that people peel back the foil packaging rather than try to break the tablet through, and that they have dry hands as to avoid damaging the medicine.

The syrup form is ideal for children and ensures that parents are able to administer their children’s doses precisely.

For added convenience, side effects are uncommon in desloratadine, with the most common reaction being a headache. However, as with all medication, there is the potential for more serious and even life-threatening reactions. For this reason, it is important to keep track of any reactions, read all the medicine's documentation before taking and discuss any concerns with your doctor.