Cetirizine vs Loratadine

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For individuals suffering from allergies, certain drugs that inhibit the release or action of histamine can help in managing symptoms. Cetirizine and Loratadine are two such medications commonly prescribed for allergic reactions. They each impact different aspects of histamine action but both have anti-allergic effects in patients with allergies. Cetirizine is a second-generation antihistamine, effectively blocking H1 receptors thus alleviating allergy symptoms caused by histamines released during an allergic reaction. On the other hand, Loratadine also belongs to the class of second-generation antihistamines; however, it has a longer duration of action compared to cetirizine and is less likely to cause drowsiness - a common side effect associated with many antihistamines.

What is Cetirizine?

Cetirizine (the generic name for Zyrtec) and Loratadine (sold under the brand name Claritin) are both second-generation antihistamines, which represent a significant improvement over first-generation antihistamines due to fewer side effects. Cetirizine was approved by the FDA in 1995. Both drugs work by blocking histamine receptors in the body, thus reducing symptoms of allergies such as sneezing, itching, watery eyes, and runny nose. However, Cetirizine is known to be slightly more effective than Loratadine at relieving symptoms of allergic rhinitis and chronic urticaria (hives). It also seems to have longer-lasting effects compared to Loratadine, meaning it can be taken less frequently. While both drugs are generally well tolerated with minimal side effects, Cetirizine has been reported to cause drowsiness more often than Loratadine.

What conditions is Cetirizine approved to treat?

Cetirizine is approved for the treatment of various allergy-related conditions, including:

  • Allergic rhinitis, also known as hay fever
  • Chronic urticaria, commonly referred to as hives
  • Itchy skin condition due to allergies (allergic dermatitis)
  • Swelling and redness of the inner layers of skin (angioedema)

How does Cetirizine help with these illnesses?

Cetirizine aids in the management of allergy symptoms by blocking the effects of histamine, a substance involved in allergic reactions. It does this by acting as an antagonist at the H1 receptor, preventing histamine from binding and causing inflammatory responses. Histamine is a chemical your body produces during an allergic reaction that leads to common allergy symptoms such as sneezing, itching, watery eyes, and runny nose. Therefore, by blocking histamine's action on these receptors with cetirizine intake, one can alleviate the negative effects of allergies and help patients manage their condition more comfortably.

What is Loratadine?

Loratadine, marketed among other brands as Claritin, is an antihistamine that counters the effects of natural chemical histamines in the body. It works by blocking H1 receptor sites and prevents the action of histamine on these receptors; this reduces symptoms like watering eyes and runny nose caused by allergies. Loratadine was first approved by the FDA in 1993. Since loratadine does not cross blood-brain barrier effectively, it is less likely to cause drowsiness compared to first-generation antihistamines such as diphenhydramine (commonly known as Benadryl). This aspect makes its side-effect profile different from those drugs – particularly in terms of causing less sedation - a common side effect with older generation antihistamines. The effects can be beneficial for treating allergic reactions especially in patients who do not respond well to "typical" first-generation antihistamines.

What conditions is Loratadine approved to treat?

The FDA has approved loratadine for use in managing the following conditions:

  • Seasonal Allergic Rhinitis, commonly known as hay fever
  • Perennial Allergic Rhinitis or year-round allergies
  • Chronic Idiopathic Urticaria, more widely known as long-term hives without a known cause.

How does Loratadine help with these illnesses?

Histamine is a chemical compound that plays an essential role in the immune system, and it's primarily responsible for many of the symptoms associated with allergies such as sneezing, itching, runny nose, and watery eyes. Loratadine functions by blocking histamine receptors in the body, thereby reducing these allergic responses. It also maintains some anti-inflammatory properties which further aid in symptom relief. Consequently, loratadine has become a go-to treatment for individuals suffering from seasonal allergies or other conditions where histamines are over-produced such as urticaria (hives). As a second-generation antihistamine, Loratadine causes less drowsiness compared to first-generation counterparts but may still cause more somnolence than cetirizine. For patients who do not respond adequately to "typical" antihistamines like cetirizine or those who prefer less sedating options due to lifestyle demands or side-effect profiles; loratadine remains an effective alternative choice.

How effective are both Cetirizine and Loratadine?

Both Cetirizine and Loratadine are second-generation antihistamines, widely used to alleviate allergy symptoms. They were approved by the FDA in the 90s, with only a few years between their approvals. Since they act on histamine receptors differently, they may be recommended under different circumstances. The effectiveness of cetirizine and loratadine in mitigating allergic reactions was directly studied in several double-blind clinical trials; both drugs exhibited similar efficacy while also showing promising safety profiles. In these studies, no significant differences emerged when comparing measures of efficacy for treating allergies between patients receiving cetirizine or loratadine.

A 2003 review showed that cetirizine is effective at relieving symptoms of allergies from the first dose taken and carries a side effect profile comparable to other popular antihistamines. It's also well-tolerated across various age groups including children and elderly populations. As one of the most commonly prescribed antihistamines globally, there is extensive research supporting its use for managing allergies.

According to a meta-analysis published in 2019, loratadine appears more effective than placebo in reducing allergy symptoms but shows comparability with other common antihistamines such as cetirizine concerning efficacy levels. However, because it causes less drowsiness than some alternatives (including cetirizine), loratadine might be preferred when sedation would be particularly problematic - like during daytime or for individuals who operate heavy machinery regularly.

abstract image of a researcher studying a bottle of drug.

At what dose is Cetirizine typically prescribed?

Oral dosages of Cetirizine range from 5–10 mg/day, with studies indicating that a daily dosage of 10 mg is sufficient for relieving symptoms of hay fever and other allergies in most adults and children over six years old. Younger children may be started on a lower dose of 2.5-5 mg per day depending on their age and weight. If there's no response after several days, the dosage may be increased by your doctor under careful monitoring. Under no circumstances should the maximum daily dose exceed 20mg for adolescents aged 12 to 17 or adults, or more than 10mg for younger children.

At what dose is Loratadine typically prescribed?

Loratadine treatment for allergies and hives is usually commenced at a dosage of 10 mg per day. For adults and children over six years, the recommended dose is one 10 mg tablet or two teaspoons (5ml each) of syrup once daily. Children aged two to five are typically prescribed half this amount, i.e., one teaspoon of syrup or a 5mg chewable tablet once daily. The maximum dose for Loratadine is set at 10 mg/day, which should not be exceeded without medical advice. In cases where symptoms persist beyond a few weeks despite adhering to the initial dosage consistently, consultation with your healthcare provider may be necessary to review your treatment plan.

What are the most common side effects for Cetirizine?

Common side effects of Cetirizine, which are usually mild and temporary, can include:

  • Drowsiness or feeling tired
  • Dry mouth
  • Stomach pain (in children)
  • Diarrhea (in children)
  • Vomiting (in children)
  • Agitation (mostly in children)
  • Insomnia

On the other hand, Loratadine is generally well-tolerated but may cause some similar side effects such as:

  • Headache
  • Fatigue/Sleepiness/Drowsiness
  • Dry Mouth
  • Nervousness
  • Difficulty sleeping

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

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Cetirizine?

In rare cases, cetirizine may cause serious side effects, such as:

  • Severe allergic reactions: hives; difficulty breathing; swelling of your face, lips, tongue or throat
  • Serious nervous system reaction: restlessness, dizziness and inability to concentrate or stay still. In extremely rare cases it can lead to tremors and convulsions.
  • Rapid heartbeat or palpitations which may be coupled with feelings of anxiety
  • Vision problems: Blurred vision or eye redness are less common but do occur in some individuals.

On the other hand, loratadine rarely causes these side effects. However, if you experience any severe symptoms like rapid weight gain (due to fluid retention), yellowing eyes/skin (indicative of liver disease) or an irregular heart rhythm while taking either medication you should seek medical help immediately. These are not exhaustive lists and if you feel unwell after starting a new drug regimen always consult your healthcare provider for advice.

What are the most common side effects for Loratadine?

When compared to Cetirizine, Loratadine can have varying side effects. Potential symptoms following Loratadine use include:

  • Dry mouth or throat
  • Headaches, dizziness
  • Gastrointestinal discomfort such as nausea and constipation
  • Stuffy nose and other common cold-like symptoms
  • Nervousness or agitation, potentially leading to sleep problems like insomnia.

Unlike Cetirizine, Loratadine is less likely to cause drowsiness making it a preferred choice for those who need to maintain alertness throughout the day. However, everyone reacts differently to medications so it's important to monitor your response closely and report any concerns with your healthcare provider.

Are there any potential serious side effects for Loratadine?

While loratadine is generally considered safe and well-tolerated, it can cause severe side effects in rare cases. These may include:

  • Signs of a serious allergic reaction or skin condition: hives, itching, fever, swollen glands, difficulty breathing, swelling of your face or throat
  • Irregular heartbeat
  • Severe drowsiness
  • Headaches that don't go away or become more severe
  • Difficulty urinating or painful urination

If you experience any of these symptoms while taking loratadine, stop using the medication and seek immediate medical attention. It's important to remember that this isn't an exhaustive list of possible side effects - if you have any unusual changes in health while using Loratadine, consult with a healthcare professional promptly.

Contraindications for Cetirizine and Loratadine?

Both cetirizine and loratadine, like other antihistamine medications, may result in side effects such as drowsiness or dry mouth. If you notice any serious reactions such as difficulty breathing or swelling of the face, lips, tongue or throat after taking these drugs, please seek immediate medical attention.

Neither cetirizine nor loratadine should be taken if you are using certain types of antidepressants known as monoamine oxidase inhibitors (MAOIs). Always inform your healthcare provider about all medications you are currently taking; MAOIs can interact with many other drugs and require approximately 14 days to clear from your system to prevent dangerous interactions with either cetirizine or loratadine.

How much do Cetirizine and Loratadine cost?

For the brand name versions of these drugs:

  • The price of 30 tablets of Zyrtec (cetirizine, 10mg) averages around $15-$30, which works out to about $0.50-$1/day.
  • The price for a similar quantity of Claritin (loratadine, 10 mg), is approximately $20-$35, working out to roughly $0.66 - $1.17/day.

Thus, if you are taking one tablet per day as recommended for both cetirizine and loratadine then brand-name Zyrtec can be less expensive on a per-day treatment basis compared to Claritin depending upon where you shop.

For the generic versions of Cetirizine and Loratadine costs are significantly lower:

  • Generic cetirizine is available in packs from 14 up to 365 tablets with prices ranging from as low as $.02/tablet when bought in larger quantities up to about $.07/tablet when purchased in smaller quantities.

  • Similarly, generic loratadine comes in packs ranging from 10 up to several hundred tablets with costs that vary but generally range between $.03/tablet when buying large amounts upfront down to approximately $.06/tablet for smaller packages.

Again it should be noted that cost should not be your only consideration when choosing between these two antihistamines since individual responses can vary significantly. Always consult your healthcare provider or pharmacist before starting any new medication regimen.

Popularity of Cetirizine and Loratadine

Cetirizine, available as a generic and under brand names such as Zyrtec, was estimated to have been prescribed to about 8 million people in the US in 2020. Cetirizine accounted for just over 16% of antihistamine prescriptions in the US. It is considered highly effective at controlling symptoms of hay fever, pet allergies and dust mite allergies. The prevalence of cetirizine has seen a steady increase since it became available over-the-counter in 2007.

Loratadine, including branded versions like Claritin, was prescribed to approximately 24 million people in the USA during this same year. Loratadine accounts for just under half of all second-generation antihistamine prescriptions and is also listed on WHO's List of Essential Medicines indicating its importance for health systems. Similar to cetirizine, loratadine effectively controls allergy symptoms with less risk of causing drowsiness compared to first-generation antihistamines.


Both cetirizine and loratadine have strong track records in the management of allergy symptoms, supported by numerous clinical studies that indicate they are more effective than placebo treatments. These antihistamines work by blocking histamine, a substance in the body involved in allergic responses. Due to their different pharmacokinetic properties, with cetirizine having a faster onset of action but potentially causing drowsiness and loratadine being non-sedating but acting slightly slower, they may be recommended under different circumstances.

Cetirizine is often considered as a first-line treatment option for immediate relief from acute allergic symptoms due to its rapid onset of action. Loratadine could be considered as an alternative for those who require constant long-term control over symptoms or who need to avoid sedative effects common with some other antihistamines like cetirizine.

Both drugs are available in generic form which offers significant cost savings especially for patients paying out-of-pocket. Both cetirizine and loratadine offer quick symptom relief; however, this might not always be noticeable immediately after taking the initial dose.

The side effect profile is similar between the two drugs; both are generally well-tolerated but it's worth noting that cetirizine can cause sleepiness more frequently than loratadine does. Regardless of which medication one takes, it’s important to monitor any changes or unusual reactions closely when starting treatment and seek medical help immediately if severe side effects occur.