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Prescription Antihistamines


Prescription Options

Many allergy sufferers have exhausted every OTC (over-the-counter) option for treating allergy symptoms. These include products such as Benadryl, Tavist, Chlor-Trimeton, Claritin, Zyrtec, and many more. But there are other options. Several prescription antihistamines are available which your doctor can prescribe to alleviate the symptoms related to allergies. In this article I intend to provide details on the 3 currently available ORAL non-sedating prescription antihistamines marketed in the U.S. It should be noted that there are other forms of prescription antihistamines, such as nasal sprays or eye drops.  This article will only deal with the oral prescription non-sedating antihistamines.

For each product I will provide information about dosage forms, dosages, side-effects, and my opinion on their effectiveness. I will also provide links to their various websites for more information and coupons!

The 3 available prescription non-drowsy antihistamines are:

  • Allegra
  • Clarinex
  • Xyxal

Each comes in a variety of dosage forms and combinations which will be discussed as well.


Allegra (fexofenadine)

Allegra was first approved by the FDA in 1996. It is presently available in 3 different dosage forms:

  • Allegra tablets: 60mg capsule & 180mg tablet
  • Allegra ODT (orally disintegrating tablets): 30mg
  • Allegra Susp: 30mg/5ml

NOTE: In March of 2011 the Allegra family of products became available WITHOUT a prescription and the brand name "prescription" product has been discontinued. You can still get generic Allegra (i.e. fexofenadine) by prescription.

Dosing: Ages 2-11 typically take 30mg twice daily

Ages 12-Adult take 60mg twice daily or 180mg once daily

Side Effects: Viral infection, nausea/vomitting, drowsiness, dyspepsia (upset stomach), and fatigue. Yes...even though it is technically a "non-drowsy" antihistamine, it may cause some mild drowsiness in some patients.

Generic Available: YES, the oral tablets are available generically as fexofenadine.

Commentary: Allegra, because it is now available generically, is the most affordable of the prescription antihistamine options. Personally, I would recommend trying the 180mg once daily dosage form, rather than the twice daily options (for adults). Allegra is worth trying if less costly OTC (over the counter) options have been tried and unsuccessful.


Xyzal (levocetirizine)

Xyzal is the latest oral non-drowsy prescription antihistamine to come to the U.S. market. Like Clarinex, the manufacturers of Xyzal played off the effectiveness of Zyrtec (cetirizine, now available OTC) by creating a chemically more potent version of the later, known as levocetirizine (Xyzal). It was approved by the FDA in May of 2007.

Dosage Forms:

  • Tablets: 5mg
  • Solution: 2.5mg/5ml

Dosing Information:

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Adults: 5mg once daily in the evening

Children (6-11 years old): 2.5mg once daily in the evening

Side Effects: Drowsiness and fatigue.

Available Generically: YES, Xyzal tablets are now available generically.

Commentary: Xyzal is the new kid on the block. Although classified as "non-drowsy" it caused significantly more drowsiness than placebo in controlled trials. Due to the cost and higher incidence of drowsiness, I personally rank Xyzal as a "last option" amongst all the othe choices.

FREE TRIAL OFFER: The manufacturer is currently offering a free 5-day trial. Click here for details.


Clarinex (Desloratadine)

Clarinex is the prescription son (or daughter if you prefer) of the previously prescription-only antihistamine product known as Claritin (loratadine). Our body converts loratadine to the active metabolite and potent antihistamine known as desloratadine. Thus, as the patent was nearly expired on Claritin, the manufacturer decided to produce this active metabolite as a completely new and separate prescription product known as Clarinex. Thus, while Claritin became available generically, and eventually over the counter, the manufacturer was able to maintain a prescription only non-generic brand on the market. Clever strategy! Although wise consumers will note that the effectiveness of Clarinex is not likely to be significantly different from the much less expense OTC Claritin product.

Dosage Forms:

  • Clarinex Tablets: 5mg
  • Clarinex ODT: 2.5mg & 5mg
  • Clarinex syrup: 0.5mg/ml

Dosing: 12 years - Adult: 5mg once daily

6-11 years: 2.5mg once daily

2-5 years: 1.25mg once daily

Side Effects: Headache, pharyngitis, xerostoma (dry mouth), fatigue, dyspepsia (upset stomach), and dizziness.

Generic Available: NO

Commentary: Clarinex is not available generically and is therefore more expensive than Allegra generic. For those who have tried the OTC options unsuccessfuly, and for whom Allegra is not effective, Clarinex may be an option worth considering. Click here for a $25.00 COUPON to help reduce the cost of your prescription for Clarinex.


Well, now you have the most important information on the currently available oral non-drowsly prescription antihistamines.  As mentioned before, I think that many effective OTC options are available and should normally be tried first.  When these fail, consider one of the above options in consultation with your physician. 

For more helpful information on treating allergies, check out this Mayo Clinic article.

Best wishes for a sneeze-free season!


Ome Ogbru on July 13, 2012:

Nice review. Very useful.

Nomascus concolor from A Country called Earth on February 27, 2012:

Thanks for your advise, I will keep them in mind... I am trying Loratadine at the moment and have not experienced any drowsiness or other side effects yet.

Jason Poquette (author) from Whitinsville, MA on February 26, 2012:


Astelin, Astepro and Patanase are prescription nasal antihistamines that can be used daily. Also, nasal steroid sprays can be used daily too, like Flonase, Nasacort AQ or Veramyst.

Nomascus concolor from A Country called Earth on February 26, 2012:

Do you know any nasal spray that could be used on a daily basis? Would it be less likely to cause drowsyness? I will have a look at the ones you described below as well...

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