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Doctor insights on: Anti Histaminics

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Dr. Paul Carter
601 doctors shared insights

Antihistamine (Definition)

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


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Why does histamine cause bronchoconstriction and is that why we are told to take antihistamine?

Why does histamine cause bronchoconstriction and is that why we are told to take antihistamine?

No: Histamine is a potent bronchoconstrictor. However anti histamines are not very effective at relieving bronchoconstriction they are mainly used for relief of itchiness and hives. ...Read more

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Can i take expectorant+antihistamine combi cough syrup? aren't the actions contradictory? expectorant increasing & anti-histamine drying secretions?

Can i take expectorant+antihistamine combi cough syrup? aren't the actions contradictory? expectorant increasing & anti-histamine drying secretions?

No: Not contradiction, rather complementing each other, antihistamines act as cough suppressants besides help decrease excessive secretions, expectorants rather loosen the thick secretions helping to get rid of them, that's why plain water is the best expectorant ...Read more

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Do histamines (not antihistamine medications) make you drowsy? Antihistamines (no decongestants added) seem to make me more alert when allergies flare

Yes: Histamine is a substance released during an allergic attack and can cause drowsiness. Some of the older generation anti-histamine agents (like benedryl) can cause drowsiness because they can pass the "blood brain" barrier and cause a direct effect on thinking. In rare cases in adults, antihistamines can cause agitation. ...Read more

Dr. Al Hegab Dr. Hegab
2 doctors agreed:
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Zantac (ranitidine) has histamine ingredients. I'm taking it recently.noticed some inverse effect,my hives is not popping out too!It should be antihistamine right?

Dr. Al Hegab Dr. Hegab
2 doctors agreed:

Zantac (ranitidine): Is an antihistamine itself, it blocks H2 receptors, histamine has more than one type of receptors in the human tissues. H1, blocked by the usual antihistamines, H2, plays a role in stomach acid regulation, which zantac (ranitidine) blocks. Zantac at times is used in severe allergic reactions or severe urticaria, together with H1 blockers to control symptoms, so your deduction is right ...Read more

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How many anti histamines can you take daily?

How many anti histamines can you take daily?

Diphenhydramine: 300 mg/day from all sources, 50 mg in one dose q 6 hours, it is the most widely used OTC. Other OTC 2nd generation antihistamines as cetirizine , loratadine or fexofenadine have different dosing but can be taken once a day, and develop tolerance as with diphenhydramine with prolonged usage ...Read more

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What is the proper dosage of anti-histamine?

What is the proper dosage of anti-histamine?

Package instructions: The package instructions will give the recommended dosages for over the counter medication. Prescriptions will give the proper dosing of antihistamines and other medications. Usual dosing takes into account other medications you might be taking plus a margin of safety. When in doubt, ask your physician. ...Read more

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What are the common effective anti-histamines?

What are the common effective anti-histamines?

Anti-histamines: They can be h1-receptor antagonists such as Benadryl (diphenhydramine) or periactin or loratadine. Or, h2-receptor antagonists such as tagamet or ranitidine. Or, h3/h4 receptor antagonists (experimental) such as thioperamide. Or, atypical antihistamines such as catechin. Or, others such as cromolyn. ...Read more

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Overdosing on anti histamine tablets bad for you?

Overdosing on anti histamine tablets bad for you?

Yes: Overdosing on anything is bad for you. Although these drugs are safe, you must be cautious in taking them. ...Read more