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Doctor insights on: Antihistamines Dont Work

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Will out of date antihistamine tablets still work ?

Will out of date antihistamine tablets still work ?

Maybe: Medications that have passed the expiration may still work, but the pharmaceutical manufacturer cannot guarantee their effectiveness. The longer the medication is out of date, the more likely they are less effective. ...Read more

Benadryl (Definition)

Diphenhydramine is a sedating antihistamine which is a kind of antihistamine type drug (common ...Read more


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What is the average time needed for an antihistamine to begin to work?

What is the average time needed for an antihistamine to begin to work?

45-90 minutes: Antihistamines taken by mouth begin to work in about an hour but may take longer if you've just eaten. Antihistamine nasal sprays (astepro, patanase) begin to work in 30 minutes. An antihistamine injection, usually diphenhydramine, sometimes given for a severe allergic reaction or anaphylaxis begins to work in a few minutes. ...Read more

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Do antihistamines work for skin reactions?

Do antihistamines work for skin reactions?

Possible: Antihistamines work by blocking histamines. Histamine is a chemical that can cause itchiness and hives. So it is possible that antihistamines can help for skin reactions. ...Read more

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What antihistamines work the fastest and are most effective ? With the tablets do you chew them or take with water ?

Antihistamines: Most antohistamines work wothin 30-45 minutes, if taken orally it does not speed their effect, either chewed or swallowed, mit is faster if given intravenous. ...Read more

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If all antihistamines work for generalized itching, is it then not caused by an systematic disease or anything serious? Im a hypocondr and often itch.

If all antihistamines work for generalized itching, is it then not caused by an systematic disease or anything serious? Im a hypocondr and often itch.

Possibly: Dry skin by far is the most common cause of generalized itching. Try using unscented lotion soap and apply a moisturizer immediately after bathing. If this does not work, then check with your doctor to check out for other potential conditions. Antihistamine works for some conditions but only when it is mediated by histamine. ...Read more

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How many weeks does it take for claritin (loratadine) 10mg to work? How long should I give it a try before deciding to switch to a different antihistamine?

A few hours: Claritin (loratadine) should start working within a couple of hours. If it doesn't not help at all, then switching to another won't do you much good. If it does help somewhat, then you may try the other alternatives which may possess more antihistamine effect than Claritin (loratadine). ...Read more

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Allergy shots or antihistamine pills which works better?

Allergy shots or antihistamine pills which works better?

Allergy shots: antihistamines only cover up symptoms and don't cure anything. Allergy shots treat the cause and that is why with successful immunotherapy you can get rid of antihistames. One complication of nasal allergy treated symptomatically is development of asthma. On the other hand if you treat the cause you prevent complications ...Read more

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How long until an antihistamine works on post nasal drip?

THEY WON'T HELP MUCH: Other than drying it up a bit and thickening it, which can cause cough. The key in trying to eliminate postnasal drip is to cut the inflammatory or environmental response that it is caused by. ...Read more

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I am anxious, stressed or even excited. I have heard that antihistamines work well to prevent this, is this true?

I am anxious, stressed or even excited. I have heard that antihistamines work well to prevent this, is this true?

Yes: Antihistamines can be helpful for treating anxiety. Psychiatrists will commonly prescribe Hydroxyzine pamoate for the treatment of anxiety that is technically an antihistamine. This medication is safer than many alternatives for anxiety and can be used in an as needed way. Talk with your physician for more information. Stay safe! ...Read more

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In class,at home,1-2/day ,Hives are oftenly occure on my full body ,tell me the best way to resolve this problem ,even antihistamines doesn't work .

In class,at home,1-2/day ,Hives are oftenly occure on my full body ,tell me the best way to resolve this problem ,even antihistamines doesn't work .

Larger dose: Try a non-sedating antihistamine up to 4 x daily ( yes much larger than what is used for hay fever). If this does not help. you may add a H2 antagonist such as Pepcid (famotidine) or ranitidine twice daily. If this happens only at home or at school, then there is something in that environment causing the hives. Consult an allergist if the above measures didn't help. ...Read more

Dr. Paul Carter
601 doctors shared insights

Antihistamine (Definition)

Sedating and non-sedating antihistamines prevent and treat allergic reactions, and are ...Read more