Over-the-counter Allergy Medication: A Comparison

Diphenhydramine
There are five different types of over-the-counter antihistamine currently available in North America specifically for treating allergies. Each one has its own possible side effects, some have been through more testing than others and some are targeted towards specific allergies while others are more global. It can be difficult, not to mention expensive, to figure it all out.

Please keep in mind that the information on the following drugs is for the main ingredient alone. Most of these antihistamines are sold in combination with other drugs, most commonly pseudoephedrine, which carry their own risks and benefits. Always read the labels carefully before taking and consult with your doctor or pharmacist if you have any questions.

Diphenhydramine (Sold as Benedryl)

Dipenhydramine has been approved for use in the United States since 1946. It fares well even today as a fast, effective way to treat allergies with studies showing it more effective than many of the newer generation allergy drugs. It is particularly effective against life threatening allergic reactions. Unfortunately, for most people it also causes such intense drowsiness that it is also the main ingredient in many over the counter sleep preparations like Nytol, and Tylenol PM.

  • Used to treat: all allergic reactions
  • Common side effects: extreme drowsiness, dizziness, difficulties with coordination and concentration, constipation, and dry throat and mouth and increased sensitivity to the sun
  • Rare side effects: nausea, hives, irritability, headaches, difficultly urinating and irregular heart beat
  • Warnings: Children are more likely to have an opposite reaction, becoming agitated, restless and excitable rather than sedated. It is not recommended at all for children under two. The elderly are more likely to experience all side effects including chest tightness, not usually displayed in younger people. It is classed as a Category B drug, indicating that it is unlikely to harm an unborn baby. It is however not recommended for those who are breastfeeding.

Cetirizine (sold as Zyrtec and Reactine)

Cetirizine, previously a prescription drug is now available over-the-counter in most of the world. The advantage to this second generation antihistamine is that it is long lasting, fast acting and doesn’t cause drowsiness in most people.

  • Used to treat: seasonal allergies, rhinitis, perennial rhinitis, and allergies to dust mites, mold and animals
  • Common side effects: sleepiness, dizziness, fatigue, dry mouth, nausea and headache.
  • Rare side effects: difficulty breathing or swallowing, abdominal pain and vomiting, coughing and nosebleeds
  • Warnings: Cetirizine is not recommended for people on any of the Benzodiazepines (Xanax, Valium, Librium etc.) or SSRIs (Zoloft, Prozac etc.) It is classed as a Category B drug, indicating that it is unlikely to harm an unborn baby. It is however contraindicated for those who are breastfeeding and for children under two. Not enough testing has yet been done to say whether older populations are more susceptible to side effects.

Fexofenadine (sold as Allegra)

Fexofenadine was developed to replace terfenadine (sold as Seldane) when it was taken off the market due to health concerns. Like the other second generation antihistamines, it doesn’t cause drowsiness in most people. Unlike the other second generation antihistamines, fexofenadine must be taken twice a day.

  • Used to treat: seasonal allergic rhinitis and hives
  • Common side effects: nausea, diarrhea, headache, muscle pain, cough and dizziness
  • Rare side effects: fever, chills and other flu-like symptoms
  • Warnings: Fexofenadine should not be taken in combination with nizoral, antacids, St. John’s Wort or erythromycin. As a category C it should not be taken by pregnant women. It is also not recommended for children under two. The American Academy of Pediatrics lists fexofenadine as usually compatible with breastfeeding.

Loratadine (sold as Claritin and Aerius)

Loratadine has been around the longest of the second generation antihistamines, it was first approved for use by the FDA in 1993 and has been well studied in populations over six years of age.

  • Used to treat: seasonal allergic rhinitis and hives
  • Common side effects: headache, fatigue, nervousness, dry mouth and stomach pain. Nervousness and fatigue occur more often in children than adults.
  • Rare side effects: irregular heartbeat, jaundice and seizures
  • Warnings: people with narrow angle glaucoma, peptic ulcer or prostate problems should not take loratadine. It is classed as a Category B drug, indicating that it is unlikely to harm an unborn baby and The American Academy of Pediatrics lists loratadine as usually compatible with breastfeeding. It is not recommended for children under two and has not been well studied in children under six.

Desloratadine (sold as Clarinex)

A 2003 study found that users of loratadine who experienced side effects, particularly night waking and nervousness were more satisfied with desloratadine. These results were confirmed by a Belgian study in 2010.

  • Used to treat: seasonal allergic rhinitis and hives
  • Common side effects: headache, muscle pain, nausea, dry throat and mouth and dizziness
  • Rare side effects: loss of appetite, stomach pain, jaundice and nosebleeds.
  • Warnings: as a category C desloratadine should not be taken by pregnant women and is not advised for those breastfeeding. Desloratadine should not be taken with other antihistamines. Check with a doctor before giving to children under two.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.

Sources:

Efficacy of diphenhydramine vs desloratadine and placebo in patients with moderate-to-severe seasonal allergic rhinitis accessed 7 February 2011

Zyrtec prescribing informationaccessed 7 February 2011

ALLEGRA SUMMARY from DrugLib.com accessed 7 February 2011

Loratadine –RXList accessed 7 February 2011

American Academy of Pediatrics accessed 7 February 2011

Assessing satisfaction with desloratadine and fexofenadine in allergy patients who report dissatisfaction with loratadine, Daniel J. Glass and Anne S. Harper, 2003

Safety and efficacy of desloratadine in subjects with seasonal allergic rhinitis or chronic urticaria: results of four postmarketing surveillance studies. Bachert C, Maurer M. 2010