Prescription medication · Second-Generation Antihistamine
desloratadine
Also sold as Clarinex. This medicine treats allergy symptoms.
Data updated 2026-05-15
- 10,248
- FDA reportsModerately reported
- 5
- InteractionsFew interactions
- 52% less
- Generic vs brandBig savings
- $8.06
- Brand price (NADAC)
What the data shows
desloratadine (Clarinex) is a prescription Second-Generation Antihistamine, reported less often than most tracked drugs (10,248 FDA reports), whose generic runs roughly half the brand price or less (52% less).
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
desloratadine (Clarinex) is a prescription Second-Generation Antihistamine. This medicine treats allergy symptoms.
Desloratadine is an antihistamine medicine. It helps relieve allergy symptoms.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Brand Price
$8.06/unit
Generic Price
$3.86/unit
Generic Savings
52%
Generic Available
Yes (5 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats allergy symptoms.
Common side effects
Sore throat, Dry mouth, Muscle pain
Key warnings
Stop taking this medicine and get medical help right away if you have an allergic reaction.
The sections below are summarized in plain English from desloratadine's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Desloratadine blocks histamine in your body. Histamine is a substance that causes allergy symptoms. By blocking histamine, this medicine reduces those symptoms.
How to Take It
Take one 5 mg tablet once a day. You can take it with or without food. If you have liver or kidney problems, take one 5 mg tablet every other day. Talk to your doctor if you have questions.
This is a plain-language summary of desloratadine's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Not enough studies have been done to know if desloratadine is safe during pregnancy. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if desloratadine passes into breast milk.
This is a plain-language summary of desloratadine's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of desloratadine's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store desloratadine tablets at room temperature, away from heat and light, in a child-resistant container.
Side Effects (from patient reports)
Based on 10,248 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for desloratadine, by number of reports
- Tiredness
Tiredness
602 reports
- Feeling sick to your stomach
Feeling sick to your stomach
583 reports
- Difficulty breathing
Difficulty breathing
532 reports
- Head pain
Head pain
465 reports
- Loose stools
Loose stools
448 reports
- Feeling faint
Feeling faint
439 reports
- Itching
Itching
422 reports
- Throwing up
Throwing up
403 reports
- Skin eruption
Skin eruption
374 reports
- Discomfort
Discomfort
318 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for desloratadine each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where desloratadine sits
desloratadine has more FDA adverse-event reports than 40% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is desloratadine; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 10,248 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
10,248
Reports Mentioning Death
535
5.2% of reports — not proof of cause
Hospitalization Reports
3,888
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | FATIGUE | 601 |
| 3 | NAUSEA | 582 |
| 4 | DYSPNOEA | 532 |
| 5 | HEADACHE | 465 |
| 6 | DIARRHOEA | 448 |
| 7 | DIZZINESS | 439 |
| 8 | PRURITUS | 422 |
| 9 | VOMITING | 402 |
| 10 | RASH | 374 |
| 11 | PAIN | 317 |
| 12 | ASTHENIA | 316 |
| 14 | ARTHRALGIA | 312 |
| 15 | PYREXIA | 309 |
| 16 | ACUTE KIDNEY INJURY | 303 |
| 17 | URTICARIA | 294 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Stop taking this medicine and get medical help right away if you have an allergic reaction. Signs of a reaction include rash, itching, hives, swelling, trouble breathing, or anaphylaxis.
Known Drug Interactions
[ See Clinical Pharmacology (12.3) .] 7.2 Fluoxetine In controlled clinical studies co-administration of desloratadine with fluoxetine, a selective serotonin reuptake inhibitor (SSRI), resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.
Mechanism: Fluoxetine slows down how your body breaks down desloratadine, which leads to higher levels of the allergy medicine in your blood. However, these higher levels are not known to cause any extra safety problems.
What to do: You can usually take these together without changing your dose. Watch for any unusual side effects and let your doctor know if you feel different.
7 DRUG INTERACTIONS 7.1 Inhibitors of Cytochrome P450 3A4 In controlled clinical studies co-administration of desloratadine with ketoconazole, erythromycin, or azithromycin resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.
Mechanism: Azithromycin blocks the enzymes that normally clear desloratadine from your system, causing the allergy medicine to stay in your body longer. Even though levels go up, it does not typically cause harmful effects.
What to do: No special changes are usually needed when taking these two drugs together. Continue taking your medications as prescribed and report any concerns to your doctor.
7 DRUG INTERACTIONS 7.1 Inhibitors of Cytochrome P450 3A4 In controlled clinical studies co-administration of desloratadine with ketoconazole, erythromycin, or azithromycin resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.
Mechanism: Ketoconazole stops the body's natural process for breaking down desloratadine, which increases the amount of medicine in your bloodstream. This increase has not been shown to cause any dangerous side effects in clinical studies.
What to do: You can take these medications together safely without adjusting your dose. If you notice any new or worsening side effects, contact your healthcare provider.
7 DRUG INTERACTIONS 7.1 Inhibitors of Cytochrome P450 3A4 In controlled clinical studies co-administration of desloratadine with ketoconazole, erythromycin, or azithromycin resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.
Mechanism: Erythromycin interferes with the enzymes that process desloratadine, leading to higher-than-normal levels of the allergy drug in your body. These higher levels are generally considered safe and do not change how the drug works.
What to do: No dosage adjustments are necessary for this combination. Simply monitor how you feel and talk to your doctor if you have any questions.
[ See Clinical Pharmacology (12.3) .] 7.3 Cimetidine In controlled clinical studies co-administration of desloratadine with cimetidine, a histamine H 2 -receptor antagonist, resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.
Mechanism: Cimetidine slows down the liver's ability to process desloratadine, which leads to higher levels of the medicine in your blood.
What to do: No special action is needed because these higher levels have not been shown to cause safety problems.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
Can I take this with other allergy medicines?
Will this medicine make me sleepy?
How long does it take for this medicine to work?
Can I drink alcohol while taking this medicine?
What should I do if I feel worse after taking this medicine?
Can children take this medicine?
Is there a generic version of this medicine?
Can I drive while taking this medicine?
What do the tablets look like?
What if I accidentally take too much?
What are the common side effects of desloratadine?
Does desloratadine interact with other medications?
What drug class is desloratadine?
Is there a generic version of desloratadine?
Is desloratadine safe during pregnancy?
Related Medications in Second-Generation Antihistamine
Other drugs grouped near desloratadine - same-class peers and common alternatives.
azelastine
Astelin, Astepro
Azelastine nasal spray is an antihistamine medicine.
Compare with desloratadine →
budesonide nasal
Rhinocort
Rhinocort is a nasal spray that helps relieve allergy symptoms.
Compare with desloratadine →
cetirizine
Zyrtec
Cetirizine (Zyrtec) is an antihistamine medicine.
Compare with desloratadine →
chlorpheniramine
Chlor-Trimeton
Chlorpheniramine is an antihistamine medicine.
Compare with desloratadine →
ciclesonide nasal
Omnaris, Zetonna
Omnaris Nasal Spray is a medicine that helps treat allergy symptoms in your nose.
Compare with desloratadine →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
Save on desloratadine
Compare prices and find discounts at pharmacies near you. Free coupons can save up to 80% on prescriptions.
Disclosure: This link may earn us a commission at no extra cost to you. See our terms.
What the FDA Data Shows for desloratadine
The FDA label for desloratadine (sold under brand names such as Clarinex) classifies it as a prescription-only medication in the Second-Generation Antihistamine class. This medicine treats allergy symptoms. Official labeling lists 6 commonly reported side effects, including Sore throat, Dry mouth, Muscle pain.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 10,248 voluntary reports. The database also lists 5 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $3.86 versus $8.06 for the brand - a 52% generic savings.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: July 10, 2025
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages