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Doctor insights on: Anti Histaminics

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Dr. Paul Carter
634 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.

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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

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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.

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

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My doctor told me I have allergic rhinitis. He gave me a shot & said it was a "histamine shot" did I hear that wrong? Or could it be an antihistamine?

My doctor told me I have allergic rhinitis. He gave me a shot & said it was a "histamine shot" did I hear that wrong? Or could it be an antihistamine?

Antihistamine: A possible shot would be an antihistamine shot such as Benadryl. Benadryl, however, causes drowsiness and thus is undesirable sometimes. Another shot for bad allergies is a corticosteroid shot (a steroid shot), which works in a different manner compared to how antihistamines work.

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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

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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.

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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.

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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.

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How much anti-histamine meds could cause overdose?

It depends: There are several formulations out and each is unique. Luckily, these are relatively safe drugs. Treat them with respect!

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What dosage does someone overdose on anti-histamines?

Depending: ...On the antihistamine in Question, do not use more than the recommended doses on the package unless instructed by your physician

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Can a child of nine years take a anti histamine pills?

Some can, some won't: I have had 2 yo kids develop the skill needed to handle taking a pill or tablet. Whether it is the proper dose at that age would depend on the medication.

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Can a child of nine years take an anti histamine pills?

Can a child of nine years take an anti histamine pills?

Yes, if healthy: Antihistamines are available in pills, chewable tablets or liquid and can be safely taken by children of almost any age. Doses are not well defined in children less than 2 yrs of age.

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Can I take anti histamine after a drink?

I would encourage: You to be very careful, as both alcohol and antihistamines combined can be very sedating. You should really try to avoid this combination.

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Which anti-histamine is best for hayfever?

Which anti-histamine is best for hayfever?

Many choices: There are many excellent choices for antihistamines that are effective for treating hayfever. The new generation products work well and have few side effects. These include zyrtec (cetirizine), Allegra (fexofenadine), Claritin (loratadine), Clarinex (desloratadine) and xyzal (levocetirizine). The good news is that they are available without a prescription and most are available in several forms.

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Would anti-histamine help with histiocytoma?

Not likely: Histiocytes are cells that are part of the immune system active in engulfing bacteria and other foreign material. Since they really don't release histamine, antihistamines are not likely to help. If the tumor was a mastocytoma, antihistamines would be a great choice.

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If I'm super itchy, will anti-histamines work?

If I'm super itchy, will anti-histamines work?

Depends: Most itchy skin rash are not mediated by histamine and thus whether it would respond to histamine or not would depend on the mechanism causing it. There is no harm in trying antihistamine even up to 4x the usual dose. The sedating ones tend to work better on itching due to sedating effect. Consult your doctor if antihistamine does not work.