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Allergies Blog

By Daniel More, MD, About.com Guide to Allergies

Xyzal: State of the Art Antihistamine

Tuesday October 9, 2007
A new antihistamine, Xyzal, became available last week, and is indicated for the treatment of allergic rhinitis and urticaria (hives). Xyzal (levocetirizine), is the active isomer of Zyrtec (cetirizine), a very effective and successful antihistamine.

All chemical structures in nature, including drugs, occur in mirror images, or isomers, of one another. This is similar to a person having a right and left hand. Typically, only one of these isomers is the active medication, the other just gets in the way (imagine shaking someone's right hand with your left hand). Zyrtec is both the left and right hands, while Xyzal is the left hand only (in this case, the active drug is the "left hand" form of the drug).

Since Xyzal is the isomer that provides the desired effects of the medication, it is expected to block the histamine receptor about twice as well as Zyrtec, while at the same time causing only half the sedation. For those people who experienced a tremendous benefit for their allergies and hives by taking Zyrtec, but felt too sleepy while taking it, Xyzal might be just what the doctor ordered.

Find out more about antihistamines in the treatment of allergies.

Comments

October 9, 2007 at 7:08 am
(1) Reader says:

If I’m understanding your analogy correctly re: shaking hands, don’t you mean that Xyzal is the right hand only?

October 9, 2007 at 11:47 am
(2) allergies says:

No, in this case, the active drug is the “left hand”, or L-isomer. Sometimes the active drug is the “right hand”, or D-isomer, but is not the case with cetirizine.

October 26, 2007 at 1:23 pm
(3) Hampson A. Sisler, M.D. says:

I have severe systemic allergy problems — but not asthma. I used xyzal for a few days and, unfortunately, had vestibular problems:
postural vertigo, to be exact. A few days after stopping the xyzal and returning to claritin, I was O.K.

The xyzal was more effective than claritin, however, and I miss its superior antihistamine effect.

Hampson A. Sisler, M.D.,F.A.C.S., sahh@att.net
28 West 12th St., N.Y., NY 10011-8654

November 28, 2007 at 11:40 am
(4) Heath Magsig says:

If you could please provide where you found the information that Xyzal is supposed to work twice as well as Zytec.

December 1, 2007 at 10:14 am
(5) Heath Magsig says:

Thanks for your previous response. One other question I have is about the comment regarding half the sedation. After reviewing both PI’s. It seems that Xyzal has more sedation compared to placed. The Zyrtec PI states about a 2:1 maybe a bit more somnolence of Zyrtec vs Placebo. In the Xyzal PI it shows a 5:1 ration of Xyzal somnolence vs placebo. So the question is, not comparing pi to pi, but vs placebo. Where do you get your information that Xyzal has half the sedation/somnolence of Zyrtec (maybe it has more and thats why its reccomended to take at night)?

Regards,
Heath

January 31, 2008 at 11:09 am
(6) Bob says:

I took my first XYZAL before bedtime last night. I’ve tried most all the OTC antihiltimines and they all seem to allow me to sleep well for about 3-4 hrs, then I wake up, unable to sleep again without taking more meds. XYZAL allowed me to sleep well all night. That is maybe the greatest benefit, so far. It’s antihistimine is as good or better than any OTC and seems to last the whole day with only one pill. I’m likin’ it. “CUDOS” to XYZAL. I just hope it comes down in price.

February 5, 2008 at 12:52 pm
(7) Meg says:

I took Xyzal at its word and popped my first one mid-day. Two hours later I was flat on my bed feeling as if I’d been run over by the “sleep bus” — no way can I take this during the day!

February 8, 2008 at 11:31 am
(8) Aaron Haack says:

up until about 6-7 months ago, I was on Zyrtec for 2 years to treat my chronic urticaria (hives). I quit taking it because the side effects were not worth the pay-off. i was still getting hives everyday while on the stuff..

A few months after I stopped taking it, I found a new Dr. that specialized in treating urticaria and he perscribed me Xyzal (among other anti-histimines)and since then, i’ve had very few outbreaks (no more than 5)

I really do think that Xyzal was a help for my condition so give it a try if you suffer, thanks! Aaron Haack

February 13, 2008 at 9:46 pm
(9) Mimi says:

Xyzal is the best treatment for uticaria. The first 4 or 5 days you are sleepy, but if you take them at night, your system will get used to it and you can take it in the daytime after that. It’s better than Zyrtec.

February 16, 2008 at 9:35 am
(10) Brandy says:

I’m on my third day with Xyzal. I don’t know yet if it’s effectively handling my allergy symptoms but I do know that it’s knocking me out. The first night I took it, I had to call in to work the next day. I slept until noon. Now, on the third day, I’m sitting at my desk at work and I can barely keep my eyes open. I hope this is worth it.

March 26, 2008 at 1:04 am
(11) KEVIN says:

My wife started this medication about 2 weeks ago for the treatment of a bad sneezing problem she has. About 1 week into the treatment she noticed a small but annoying rash on both legs, 3 days later she was suffering from shortness of breath and bronchial wheezing. After many breathing treatments and 4 doses of benadril she was ok but had to stop the Xyzal none-the-less, what a shame too as it was controling the sneezing!

April 26, 2008 at 5:02 pm
(12) Alice Moravec says:

Xyzal keeps me from sleeping all night long. I sleep for 2 hrs, then awake, sleep for 1 hr, then awake again. This goes on all night long.

May 8, 2008 at 5:08 pm
(13) Narayanan ammanur says:

For me none of the OTC worked beyond a few hours. Many times I keep awake all nights during allergy season due to severe breathing problems. Had taken xyzal last night and slept like I cant believe. Big problem was at 8:30 AM, I was still feeling tired and wanting to sleep more. Good thing was the allergy symptoms for the day has been mild as opposed to when I used to take Claritin/ Benedryl/ Allegra/ Singulair. There is no way, I can take this during the day.

May 8, 2008 at 9:59 pm
(14) David says:

Any weight gain? I have gained 5 lbs in 5 weeks since being on xyzal. Any connection?

May 20, 2008 at 10:59 am
(15) Elizabeth says:

Yes! I started xyzal about 4 weeks ago and have gained 5 lbs and this despite actually increasing my time at the gym and eating the same as always. I’ve been wondering if it might be the xyzal and was planning on seeing what happens if I take a break from it since its “low allergy” season.

May 24, 2008 at 10:05 pm
(16) Amy says:

I also gained a crazy amount of weight in a very short time while taking this drug for CIU and I am a Spin instructor who also practices yoga almost daily. I know it was the drug and I hate it becuase it really worked well for my hives. I have now switched to Allegra.

June 3, 2008 at 7:59 am
(17) Michelle says:

I LOVE Xyzal with no side effects. I suffered from severe allergies for years and the only thing that kept them under control was Zyrtec which I could not take because of drowsiness. As soon as Xyzal became available for use here in the US my doc wrote me a prescription. Since then, I have had such a better quality of life than I have had in the last 8-9 years. Thank you Xyzal!

June 17, 2008 at 9:49 pm
(18) Dyan says:

I have gained almost 30 pounds in 6 months and couldn’t figure out why. My eating habits haven’t changed. Then I recalled that I started Xyzal 6 months ago. I’m glad (but not in a good way) that it’s not just me. I was starting to panic until now! I’m getting off of Xyzal and hope to see my weight drop. To Amy and Elizabeth, did you lose the weight when you stopped?

June 26, 2008 at 1:24 am
(19) Alyce says:

I’ve been taking xyzal for about two months now, its been ok as far as my allergies go…but i’ve gained a considerable amount of weight. I’ve been dieting and exercizing like crazy, but i’m actually gaining weight. It just crossed my mind today that it could be related to my medication! I’m glad other people have had similar problems. I’m going to stop taking it and see what happens…any suggestions on a OTC allergy medication to take in the mean time??

June 26, 2008 at 7:16 pm
(20) Gwen says:

What ingredient in this product that causes weight gain? My doctor told me to stop taking my allergy medication because it causes weight gain.

June 30, 2008 at 10:22 am
(21) Bill says:

I started taking Xyzal about 2 weeks ago and have gained 7 lbs. I run daily and couldn’t figure out what the problem was. I was able to run 6 miles per session before the Xyzal, but now am greatly fatigued after only 2 miles. I took it last night and weighed myself this morning when it finally hit me that the Xyzal is probably to blame. Last night is the last time I’ll be taking it. Hopefully the pounds will come off soon and my muscle fatigue will go away.

July 7, 2008 at 10:44 pm
(22) Day says:

My Dr. told me that any antihistamine can make you gain weight when taken on a regular basis. However, I’ve gained more on the Xyzal than any other med. It’s not making me very happy.

July 8, 2008 at 10:39 am
(23) Bill says:

Stopped taking Xyzal about 2 weeks ago. Weight has dropped 5 lbs already. I exercise regularly and eat healthy (most of the time). The Xyzal was the x-factor. Plus, I noticed (after stopping the meds) that my muscles are less fatigued and my breathing is easier when running. I prefer the allergies over the side-effects.

August 14, 2008 at 1:29 pm
(24) Sandy says:

I have been taking Xyzal for 1 1/2 weeks and have also experienced drowsiness I didn’t experience on any of the other allergy meds. I am now taking at night and sleep like a rock; a little dizziness during the day. My Dr started me on Xyzal to hopefully help with severe itchy, swollen eyes from mold. No med has been able to help me with this…eye drops either. Right now mold count has dropped, so will see when it rises if Xyzal does the trick. Willing to put up with side effects if it helps with eyes. No weight gain yet…will see.

October 6, 2008 at 12:58 pm
(25) Peggy says:

Wow – this is interesting. I too have gained a lot of weight – about 15 lbs in the 6 months I have been on xyzal. I too go to the gym regularly and watch what I eat, all that. I felt like something else had to be going on so I just googled “xyzal and weight gain” and voila – here we are. The only bummer is nothing else I have tried – zyrtec, claritin, benedryl etc seem to work as well without making me drowsy. Anybody found anything else?

October 6, 2008 at 8:40 pm
(26) Katherine says:

I have been taking xyzal after getting a prescription for it in April 2008. I have not experienced weight gain, but I do not take it daily. I have taken it regularly but at random intervals. If I have a particularly allergy prone morning, I suffer for the rest of the day or use a nasal spray, and then I take it in the evening with dinner. It has definitely made me less sleepy throughout the day than zyrtec and works much better than claritin. And with only taking as needed and not daily, I have not experienced any side effects other than wanting to stay in bed a little longer some mornings!

October 9, 2008 at 7:37 pm
(27) Kathy says:

Does Xyzal have a decongestant in it, or only an antihistamine?

October 16, 2008 at 1:46 pm
(28) Laura says:

I am so glad to hear of others who think they have gained weight on xyzal…I thought I was hitting the middle age spread WAY too early! I, too, run 5 times/week and do pilates w/o any change in diet, if anything, cutting back!…been wondering why my clothes have not been fitting…glad to find this source and calling my allergist right now.

October 20, 2008 at 10:29 pm
(29) Pam says:

AFter my insurance co. stopped paying for Zyrtec, I was prescribed Xyzal. I took it at night and the next day I could not keep my eyes open. The 2nd time I took it, the same thing happened. Since I have a job driving my car all day, I had to stop taking it because of the severe drowsiness. I am now on Allegra, which is not doing much of anything for me!

October 23, 2008 at 9:58 am
(30) Liz says:

My doctor gave me samples of Xyzal a little over a week ago, and it worked better on my allergies than anythign else to fight my nasal allergies. I’m just now starting to connect the fatigue with the Xyzal…and is anyone else noticing weird dreams? My dreams have been very strange.

If you want to stay away from the Xyzal, here’s hwat I was doing before that worked about 75% as well: 2 sprays of Fluticasone (I think it’s the generic version of Flonase, but it works better than flonase) at night and an Alavert tab in the morning. Alavert is a little overpriced but really good for a quick fix if you’re having a sneeze attack (which my cat often gives me).

November 3, 2008 at 11:28 am
(31) Teresa says:

I started taking XYZAL Oct 23, 2008 and since then my stomach has been hurting, I’ve gained weight, I’ve noticed that it takes my muscles longer to recover after a workout. I’m tired during the day. I have not noticed any relief from sinus congestion (maybe I need to take it longer). I still wake up in the morning with a stuffy nose and drainage. Speaking for myself, the only positive thing I can say about XYZAL is that I would sleep really well when I was taking it. After finding these comments and other information concerning XYZAL’s side effects (though they don’t mention what people are truly experiencing), I’ll be stopping my nightly dose tonight. I think I’ll try Ester C & a Neti-Pot.

November 5, 2008 at 11:41 pm
(32) dave says:

are there any long term side effects of xyzal ive been taking it now for almost a year??Is this ok??

December 31, 2008 at 4:26 pm
(33) TerryinBirmingham says:

I’ll echo the weight gain issue. I like the drug, in terms of it’s effectiveness on my allergies. BUT, it took me about 2 months to figure out the DIRECT correlation between when I took XYZAL on a dialy basis and my weight gain. I run 5 days a week, I’m 46 years old, and I’m a moderate eater. I will absolutely gain 2 to 3 pounds a week if taking XYZAL on a daily basis. Too weird.

January 10, 2009 at 6:44 pm
(34) Maslina says:

I am glad to have found the answer to my unexpected weight gain. I took xyzal for 4 months for my eczema/psorisis and have gained approximately 8 kilos!!!!!

I shall stop this medicine immediately. How long did you lose the weight you had gained after you stopped taking xyzal?

January 18, 2009 at 11:37 pm
(35) Suzanne says:

I have also noticed CRAZY vivid dreams!!

as for weight gain, i have actually lost about 5 pounds since starting xyzal.

January 21, 2009 at 9:55 am
(36) Rick says:

Has anyone had problem with their blood pressure going up while taking this medicine?

January 24, 2009 at 2:36 am
(37) Sanet says:

I had no problem sleeping nor waking while on the medication. It did however make me extremely aggressive. After 2 days I screamed at my husband over the phone and after 5 days I became so angry that he had to physically restrain me! I stopped taking it for 1 day and am back to the loving caring wife and mother my family knows.

January 26, 2009 at 12:20 am
(38) Suzanne says:

I thought this was interesting:

I was having trouble seeing close up and my distance vision also seemed to be worsening, so I went to my eye doctor. She said my prescriptions hadn’t changed, but my eyes weren’t focusing and my pupils weren’t reactive. She asked if i had was on any new medications. And I told her xyzal, which i was on for 2 weeks before i noticed the eye problems. She said that it was the antihistamine that was messing with my eyes and advised me to stop taking it, which i since have. (It was only yesterday so i haven’t noticed an improvement in my vision) She said she has seen similar problems with zyrtec.

February 7, 2009 at 12:44 pm
(39) Tammy says:

Oh my, thank you al for all your comments. now I know where all the weight gain has come from.I been taking this xyzal for about 8 months and gained about 40 pounds.And I am always tired, can’t get out of bed and I am not motivated to do a darn thing. I am going to stop taking this medication today. Does anyone know if there is a better onr out there because Spring is around the corner?

February 9, 2009 at 9:13 pm
(40) Patti says:

I’m so glad I was able to read the many comments/suggestions about xyzal. I have this medication in my cabinet and as yet, I have not taken it. I have severe allergies that just started last year in January, 2008. So far, I’ve tried multiple rx’s and otc meds, none really help and for the most part, I have terrible reactions/side effects from taking the various remedies. Perhaps I need to try something natural, any suggestions?

February 17, 2009 at 6:52 am
(41) Arzu says:

I have ideopathic urticaria and found Xyzal to be very effective with treating my skin allergy (constant itchiness and redness). HOWEVER, I, too, have noticed a weight gain of about 2 kilos in the short time I’ve been using it daily, as prescribed by my doctor, even though I eat right and work out at least 4 times a week. Now I can probably guess why….I’ll try going off the medication and see if I drop the weight. Thanks for the tips!

February 18, 2009 at 9:15 pm
(42) Lauren says:

Great site! On xyzal, I have fewer hives and the ones I have now do not itch. After weeks of feeling SO very itchy, this is like a miracle drug plus I’m not sleepy at all at work. I have gained ~1 pound/week on xyzal, but I plan to run a little more to get back into shape once the hives are gone, so this drug is totally worth it!

March 3, 2009 at 9:31 am
(43) Anthony says:

Has anyone suffered increased blood pressure from taking xyzal?

March 6, 2009 at 11:12 pm
(44) Jesse says:

My son started on xyzal 2/10/09. A few days later his personality completely changed. He is fifteen years old and I don’t know if something else also has happened which he has not shared with me. Honestly he has always been a very difficult kid; from the time he was in a crib. I was considering sending him to a boarding school because there was just too much tension in the house. He is very selfish and just plain ol, mean. I’ve talked with him about it a few times as he has also noticed how much more pleasant he is to be around. His whole life has changed. Has he suddenly taken a big leap in maturity? Is it just coincidence of the timing for beginning the xyzal? Now for the bad news; he has had a sore throat for three weeks now (coincidence?) last night his uvula ( the little thing that hangs down in the back of the throat) was very swollen to the point that he was having trouble breathing. He is better now, but I’ll see if the swelling has gone down tomorrow. He did not have a fever. He takes the medicine in the morning and has not complained of excessive sleepiness, in fact he has been working harder then ever in school. He now says that he wants to try really hard this semester and not be a looser. He’s always been on the rather thin side and so a little extra weight would be welcomed. What am I to do?

March 19, 2009 at 9:30 am
(45) kent says:

Xyzal works great on my allergy symptoms … better than anything else I’ve taken but here’s the thing. I can only take a half of a pill and only before bed and only when my allergies are really bothering me. If I take a full pill before bed, when I get up in the morning, I can’t get out of bed … PERIOD. Lately during this spring, I took both Xyzal and Zyrtec … Xyzal when my symptoms where bad and Zyrtec for maintenance. Man did I start packing on the pounds. I run, swim and lift and my weight was still going up. Just by taking a half of a ZYXAL every other day, I put on 5 lbs in two weeks. Not to mention my running was awful!!! I would only use this med if your allergies are making you suffer. I definitely wouldn’t use it as maintenance thing.

March 27, 2009 at 1:59 pm
(46) Leslie Basaric says:

Thank goodness for everyone’s comments on Xyzal! I looked online at the side effects of the drug and no where does it say weight gain or vision problems. Once I started on Xyzal I gained about 5 pounds in just about a week and a half. I also already have vision problems and its hard for my eyes to focus and this medication just made it more difficult. I prefer Claritin and the occasional Benadryl when I have a bad allergy attack over this uncontrollable weight gain.

March 29, 2009 at 7:07 pm
(47) Liza says:

I’m so glad I found this website. I was losing my mind trying to figure out why I gained 5 lbs in 2 weeks. It’s the Xyzal. I started taking the drug 2 weeks ago for allergic rhinits. I weigh myself once a week and after 2 weeks, 5 lbs heavier. I haven’t changed my eating habits and I do cardio at the gym 5 days a week. Now, I can’t remove my wedding rings and my socks leave very demarcated imprints on my ankles which is definitely new. I would rather suffer with my allergies instead of taking Xyzal.

April 10, 2009 at 9:49 pm
(48) Lisa Brodhagen says:

Wow Love xyzal for my allergies, but have also gain 5pds in one week and always seem to have an uncomfortable bloating feeling, also had the vision problems and severe dry mouth. Im really going to miss taking it but with the weight gain have no choice, very depressing as I finally found some relief. Im trying allergy shots hope they start to work has anyone tried them and had success?

April 23, 2009 at 4:56 pm
(49) Colleen says:

I have been taking Xyzal for one month and I have already gained 10 lbs. I just figured out last night it was the drug causing me to gain so much weight. I’m getting married in a few months – can anyone tell me how quickly the weight comes off once you stop taking Xyzal?

May 2, 2009 at 9:01 pm
(50) Erica says:

I’ve been taking xyzal for approximately 2 weeks because Claratin and Zyrtec are now OTC and I wanted something my insurance plan would pay for. Xyzal works great for my allergies – but I’ve been extremely tired for no reason. By mid-day I can’t keep my eyes open and by 10 pm I’m in bed. I have difficulty waking up in the morning, even after 9 to 10 hours of sleep (my normal sleep is 5-7 hours and I’m good to go). After reading all these reviews I now understand why I’m so exhausted. I’ve also gained about 3 pounds since starting it, so this may be the culprit.

May 3, 2009 at 9:35 pm
(51) Jean says:

I love Xyzal — Allegra stopped working for me; Zyrtec knocked me out; Claritin did not work for me either. I feel GREAT taking this and this is the first year in 30 that I have not been miserable in the spring!

May 8, 2009 at 11:53 am
(52) random dreamer says:

I just want to echo some of the comments on here regarding Cetirizine and Wierd Dreams.

I just bought heaps of this stuff cheap and for 2 weeks now I have crazy vivid dreams… sometimes nightmares which is not so great..

I was hounded for hours in my sleep saying the Our father prayer (???!!!!) being hounded by ghosts. Most of the other dreams have been harmless enough if very vivid.

June 1, 2009 at 10:28 am
(53) David in Nashville says:

for Jesse (44), I totally understand problem children, but as a lifelong sever allergy sufferer, I’d like you to hear that it may be possible that your son has been suffering more than you imagine. Sleep deprivation (alot of allergy sufferers deal with this) can make you a different person. The days when I can breathe are a like a gift from God.

June 14, 2009 at 12:48 pm
(54) John says:

Does anyone have a sense for the optimum xyzal dosage that they really need to control symptoms? I was quartering the pill to 1.25 mg, but was still groggy in the morning. Now I am using the liquid version (0.5 mg/mL) to control the dose. About 0.25 mg in the evening works well for me. One of the 5 mg pills is about a 20-day supply for me.

July 1, 2009 at 2:02 pm
(55) Kelly says:

I’m so glad to hear about the weight gain in other people! I started taking Xyzal a couple of months ago and I have gained 15 pounds. I started to be really careful about what I eat and stepped up my exercise routine, but nothing is helping. I was getting so frustrated b/c there was just no explanation for why I continue to gain weight.

Can anyone say how long it has taken to lose some of the weight after you stopped with the medication?

Thanks!

July 2, 2009 at 12:58 am
(56) Susan says:

Xzyal works great for controlling allergy symptoms, and I haven’t had any noticable drowsiness, but it seems to make my heart pvcs worse and the weight gain is horrible! And even with reasonable diet and excercise, it won’t come off. I’ve tried coming off of xyzal once but my allergies were too severe, but I’m going to try again. I’d rather have a rash than increase my chances of heart disease with the extra weight.

July 6, 2009 at 7:22 am
(57) me says:

I have been taking this for three days and I cant not keep my eyes open at all. Last dosage was about 24 hours ago im not taking this anymore. My nose is bleeding, my throat hurts, mouth dry, lots of drainage, and I look and feel sick …the side effects are too much if you are a working individual.

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