Overview

Claritin is the third of a new generation of allergy medicines called histamine H1 receptor antagonists. These nonsedating antihistamines are changing the way doctors control allergy symptoms.

Until these drugs became available, virtually all oral allergy medicines caused some degree of sedation. This made driving or operating machinery dangerous. Nonsedating antihistamines like Claritin now provide many people management of symptoms such as sneezing or hives without reducing alertness or coordination. And unlike other allergy medicine, Claritin does not appear to interact with sedatives.

In one popular prescription product, Claritin-D, loratadine is combined with the decongestant pseudoephedrine for quicker relief of congestion.

Side Effects and Interactions

Side effects with Claritin are not common, but people have reported headache, fatigue, drowsiness and dry mouth. Other potential reactions include weight gain, blurred vision, weakness, dizziness, nausea, anxiety, depression, impotence and menstrual changes. Report any symptoms to your doctor.

For Claritin-D, the most common side effects are headache, insomnia, and dry mouth. Indigestion and loss of appetite are reported in addition to side effects listed for Claritin alone.

Certain drugs can interact with Claritin to raise blood levels of the antihistamine. Nizoral is known to boost blood levels of Claritin, but no changes in heart rhythm or electrocardiogram (ECG) were noted as a result.

In general, it would be wise to check with your doctor or pharmacist if you must take Claritin in combination with a medicine known to interact with the similar drugs, Hismanal and Seldane. These include erythromycin (E.E.S., E-Mycin, ERYCEry-Tab, Erythrocin Stearate, etc.), Biaxin, Sporanox or Tagamet.

The pseudoephedrine component of Claritin-D can reduce the effectiveness of many blood pressure medicines and may interact with Lanoxin.

Check with your pharmacist and physician to make sure Claritin or Claritin-D is safe in combination with any other drug you take.

Special Precautions

Antihistamines should be avoided for several days before allergy skin testing, as they could interfere with the results. People with liver problems should get a reduced dose of Claritin, as they process it less efficiently.

Recent animal research suggests that Claritin and other antihistamines may promote tumor growth. We hope that further research will clarify this risk. People with cancer or at high risk of cancer should discuss this animal data with their physicians.

Claritin-D is not appropriate for people with narrow-angle glaucoma or urinary retention. It should not be taken by anyone on Eldepryl, Nardil, Parnate, or any other MAO inhibitor.

Taking the Medicine

Claritin is a long-acting antihistamine. One tablet daily will provide 24 hour coverage.

Claritin should be taken on an empty stomach, as food substantially interferes with absorption. That means at least one hour before eating or two hours after a meal. Claritin-D is also taken on an empty stomach, but two a day, 12 hours apart, are required for maximum effectiveness.

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  1. Louis S
    Reply

    Wow I have been on it for 11 years. Used to weigh 210 now 270 until this past week. I stopped taking loratadine 10 mg from target…dropped 8 lbs. in the first week. AMAZING! I read that it changes liver function.

  2. Louis
    Reply

    been on loratadine for 12 years daily as so cheap at Target. 10 years ago I weighed 210, today august 1 2014 270 lbs. I never associated the two until I realized no matter what I do I can’t lose weight. It ha never been a problem. Got off claratin 5 days ago, have dropped 8 lbs… No Dr. caught this one. Our medical community needs a lot of help. Try it you’ll see. The only thing You have to lose is 50 pounds!!! and I thought I was this terribly bad gluttonous person….

  3. SV
    Reply

    I’ve been taking Claritin off and on since it first came out. I never thought there were any side effects until now. I am getting headaches and drowsiness which is effecting my work. I got cut on a meat slicer while working in a deli and ended up quitting the job.
    I make mistakes at my other job a lot and work really slow, having a hard time concentrating. I am trying to find a more natural way to cure allergies and prayer. Hope to get off of these. It does work though.

  4. Lynne D
    Reply

    I have put on weight quickly since taking Loratadine ( Clarityn).
    However the benefits of taking it are very good for my allergies which are seasonal.
    Has anyone come off Loratadaine and if so did you lose the weight and how long did it take?
    Many thanks
    Ps I don’t feel that I am eating any more, just my stomach is getting bigger every day.
    Thanks for any advice

  5. Lightning Racer
    Reply

    Kind of odd… I know that Claritin-D does that but I use regular 24-hr Claritin and it has the same problem with me. I have forgotten two assignments (didn’t even remember anything about the class in which they were assigned), and completely lost track of days and time. Kind of annoying, but anything’s better than my allergies. I just have to write EVERYTHING down now.

  6. LR
    Reply

    I was prescribed Claritin D for 2 weeks due to fluid in one ear, and to follow with just Claritin 24 Hr daily after that. I have followed this regimen, and have noticed increasing bloating and weight gain ever since. My sinuses feel better, but my body feels awful, and I can’t wear my pants that I’ve been wearing. I’m going off the Claritin starting tomorrow. I would also be interested in knowing about an antihistamine that an osteopath would recommend.

  7. Dick
    Reply

    I have had a severe rash for about two years. No cause has been found. I’ve been patch tested for 75 substances—no reaction except gold (which I’m never near). I’m still in limbo–this past year I’ve been on prednisone twice. For the itch–two loratadine at bedtime and one in the morning. It does relieve the itch a bit. I’m really not aware of side effects—but I can’t lose weight. Initially I was also on hydroxyzine also but it made me too tired. I use triamcynalone (sp?) and rarely clobetasol to control the rash.
    Does anybody have any ideas about my rash and medications

  8. Brad
    Reply

    I have been taking Claritin (Loratadine) for about a month now for itchy and red skin. It does very little to help my problem I still get red marks on my skin all the time but they just aren’t as itchy. At first I didn’t notice any side effect but in the first week or so twice after taking the pill I got a stomach ache after I ate and felt nauseous. This was followed by extreme anxiety. I have never had anxiety at this level before. Everything around me bothered me and I just felt like I had to get out of my surroundings and even when I did I could not settle down. This was scary to me but the first two times I got it I thought it was associated with me worrying about my stomach pain and being afraid I was going to be sick in a public place (once at a restaurant and then again at baseball game). Then it happened to me at friends house, at the gym, then at work, and then 3 times in one day at my girl friend’s house.
    Even if I lay down and try and relax I still just have this hopeless feeling like everything is wrong. Its scary. I do not have any added stress in my life currently so the only thing that can be causing this is the Loratadine.
    The last time I took it was 3 days ago and I am still having bouts of anxiety. It is effecting my ability to concentrate at work and I have left early twice now because I just couldn’t handle being at there. My boss is understanding for now but if this continues I could be out of a job.
    I had problems with other antihistamines previously with causing dizziness and fatigue but nothing this severe.
    I am hoping that these side effects will go away soon as I haven’t taken the pill in 3 days.
    Has anyone else experienced this type of thing? If so how long did it take for you to stop having these issues after you quit taking it.

  9. Brad
    Reply

    I have been taking Claritin (Loratadine) for about a month now for itchy and red skin. It does very little to help my problem I still get red marks on my skin all the time but they just aren’t as itchy. At first I didn’t notice any side effect but in the first week or so twice after taking the pill I got a stomach ache after I ate and felt nauseous. This was followed by extreme anxiety. I have never had anxiety at this level before. Everything around me bothered me and I just felt like I had to get out of my surroundings and even when I did I could not settle down. This was scary to me but the first two times I got it I thought it was associated with me worrying about my stomach pain and being afraid I was going to be sick in a public place (once at a restaurant and then again at baseball game). Then it happened to me at friends house, at the gym, then at work, and then 3 times in one day at my girl friend’s house. Even if I lay down and try and relax I still just have this hopeless feeling like everything is wrong. Its scary. I do not have any added stress in my life currently so the only thing that can be causing this is the Loratadine.
    The last time I took it was 3 days ago and I am still having bouts of anxiety. It is effecting my ability to concentrate at work and I have left early twice now because I just couldn’t handle being at there. My boss is understanding for now but if this continues I could be out of a job.
    I had problems with other antihistamines previously with causing dizziness and fatigue but nothing this severe.
    I am hoping that these side effects will go away soon as I haven’t taken the pill in 3 days.
    Has anyone else experienced this type of thing? If so how long did it take for you to stop having these issues after you quit taking it.

  10. ADR
    Reply

    I have always balanced my weight at 120-123. Not a big eater, and never really had an appetite. I was prescribed Claritin from my doctor and take one every day to control my asthma and allergies. Since then I have gain in a matter of a month 10 lbs. I average 2-3-lbs gain per week, and I am always hungry. I do not take any other drugs or prescriptions. So glad I saw this article. I’m planning on getting off the Claritin to see if there is any changes in my weight and appetite.
    Thanks for the input…

  11. LMW
    Reply

    I have been taking Loratidine D for a week and have gained 5 lbs. I’m constantly hungry and have low energy. I’ve been wondering if my allergy meds are the cause of these less-than-optimal symptoms… think I’ll stop taking them and see what happens. Thanks for everyone’s input!

  12. knm
    Reply

    Actually dehydration can cause anxiety and panic attacks. Antihistamines and decongestants cause dehydration. I keep water by my bed and if I awaken with anxiety I take a few gulps and it goes away almost immediately. It took me years and the use of anxiety medications (I’m now off of them) to figure this out.

  13. Keisha
    Reply

    Has anyone taking Loratadine had any panic attacks with this pill. Please email me back to let me know.? I have been taking allergy pills for a long time and my panic attacks have got worse..

  14. Kentucky1
    Reply

    Some anxiety, impotence & weight gain were the main side effects. As far as working on sinus problems, it worked great.

  15. Northcountry1
    Reply

    I’ve had severe skin rashes and itching–I’ve been on prednisone three times. The cause of the rashes so far are not known. In the past six months I’ve been on 2 2yrtec at bedtime 2 Claritin when I wake up and two Hydroxizine if I need it. The rash is much less but I’ve developed balance and weakness problems.

  16. so
    Reply

    Took one Claritin, allergies gone, no hunger.(so far) I do not plan on daily use. Read enough to limit the use.

  17. Mrs Psarros
    Reply

    I have never had indigestion before, but since taking Loratadine (20 mg /day as prescribed by my GP) I am having really severe indigestion, to the point where I almost start to worry it’s a heart problem.

  18. JJM
    Reply

    I have been taking Singulair (Montelukast) for about 8 months. At first I was thrilled and felt like I had my life back. I am 5’1″ and neurotic about my weight and very athletic. When I started taking it, I was really struggling with exercise induced asthma, much more than allergies. I weighed about 118 pounds. I now weigh 139 pounds. I train very hard almost every day. I am taking claritin as well because of my allergies and I really don’t eat much.
    I am concerned about even more weight gain! I tried to come off Singulair but now that I am used to it I find it impossible to go back to being wheezy and miserable. My advice is that if you haven’t tried it you won’t know how wonderful and fantastic and freakin’ amazing it is. You won’t know what you’re missing. Once you go on it, you can’t go off it, no matter how lousy the side effects are.
    20 pounds on a petite neurotic weight obsessed frame is what I call a lousy side effect! but the FREEDOM is like being weightless and combined with claritin it’s even better. As long as you don’t mind the weight. It’s enough to make me want to give it all up and take up Sweatin’ With the Oldies.

  19. M Morgan
    Reply

    I have been on Claritin for about 1 month and could not understand why I was so hungry all the time. I blamed it on hormones until I googled claritin and weight gain and realized it has got to be the claritin. I have gained about 5 lbs because I’m hungry all the time. I’m not taking anymore Claritin!

  20. kate
    Reply

    I have noticed I have gained 5 pounds in a month with claritin. My allergist weighs me every visit and now he wants to put me on singulair too!! I will try for two weeks only because I do not trust drugs or drug companies.

  21. MW
    Reply

    I have been taking Claritin D for about 2 years and have memory issues since I started. I have also been taking Benadryl lately at night to sleep and it has gotten even worse. I am 39 and did not recognize my own 11 year old son a few weeks ago. I go to the Mall and forget which store I intended to shop in. I also cannot remember names of people I know very well, phone numbers, words for objects, and cannot find my keys. I often have to use the car alarm to find my car in a parking lot. I think I need to get off the allergy meds.

  22. AD
    Reply

    KS, I thought I was the only person who had that reaction to Claritin! I gained only a few pounds (about 4) but since it happened very suddenly and the only thing I had changed was taking the Claritin, I wondered if that was the culprit.
    I did a quick internet search and saw “weight gain” listed as a side effect on a few site. And now that I saw your post I am convinced so I’ll stop it and see what happens. Now looking for an herbal or homeopathic remedy for allergies.

  23. KS
    Reply

    I used Claritin daily for four years straight and gained 50 lbs in less than six months. It didn’t begin immediately: it began in about year two. I had weighed 120 lbs (I’m 5’4″ tall) for the previous eight years and NEVER had a weight problem in my life. I only figured out that it was the Claritin when I decided to stop taking it to see what would happen: I lost seven pounds in five days, and continued to lose an additional 25 lbs over the next six months. Years later, I switched to over-the-counter antihistamines and have now gained back all the weight I lost after ceasing Claritin. I conclude that all antihistamines may cause unexpected, unexplained weight gain. I guess I’ll have to suffer with allergies for the rest of my life!

  24. norman s.
    Reply

    After combining one Claritin (10 mg.) with dyphenhydramine (25), several hours later I experienced short-term memory loss lasting about 4 hours. First and only time I’ve combined these two and only time I’ve experienced this symptom.

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