Doctor insights on:
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 moreSee 1 more doctor answer
I went on antihistamines for a long time and they no longer work. Nose sprays don't either. Now have post drip. ?
Unclear: Different antihistamines have different potencies. 10 mg of Zyrtec is equivalent to 180mg of Allegra (fexofenadine). Mg doseage as in all medicines are drug specific. In regard to toxic levels, each has it's own known limit. However too much antihistamine can lead to deadly arrythmias/ Please use the recommended dose. ...Read more
Antihistamines: Safety of high dose medications is often unknown. Our experience comes from case reports of persons who intentionally or accidentally consumed unusually excessive quantities. When Claritin (loratadine) was first investigated, safety studies were done at 40 mg (4 times the current recommended dose). We take 10 mg because effectiveness is not significantly different between 10 mg and 40mg. ...Read moreSee 1 more doctor answer
"Can I": "I" is the catch in your question. I can't give advice to you in particular. The answer depends on your other known conditions and the Celexa dose. For an otherwise healthy person, 30mg daily of Celexa or less plus an antihistamine at standard dose carries a low risk for heart problems. Discuss with your doctor and the pharmacist dispensing the Celexa before going forward with the combo. ...Read moreSee 1 more doctor answer
Probably: This combination is usually safe, but individual factors may influence this. Consult your doctor to deal with your specific circumstances. ...Read more
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
It depends: It depends on the antihistamine and when you are exposed to the cause for your allergies. Antihistamine pills generally take at least 30 minutes to two hours to take effect and peak hours later. Pollen levels are highest in the morning, but if you are exposed to other allergens such as animal dander or dust, those levels would affect you at night. Take it a few hours before your worst time. ...Read more
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
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
Depends : It depends on the antihistamine. There are fast acting antihistamines such as Benadryl (diphenhydramine) and Atarax also known as Diphenhydramine and Hydroxyzine that generally last approximately 6 hours. Longer acting antihistamines such as Allegra and zyrtec also known as fexofenadine and Cetirizine generally last approximately 24 hours. ...Read moreSee 1 more doctor answer
How long does it take antihistamines to get out of your system? I was told not to take any for 1 week, but inadvertently did. Is 5 days enough time?
Maybe but it depends: I can't answer your question exactly b/c you didn't specify NSAID or antihistamine. Check out both www.Online.Epocrates.Com & www.Drugs.Com to check for medication interactions. Plug in what you're taking and both websites will warn you of possible interactions. They're not 100% foolproof but they're a good start. Better yet, ask whoever prescribed your meds. Always tell ur doc what you're taking! ...Read more
Don't understand how antihistamines work for chronic hives that is due to thyroid issues and not allergies?
Chronic Urticaria CU: CU can be associated with various autoimmune disorders. Even in the absence of hypo- or hyperthyroidism, patients with thyroid autoantibodies are often poorly responsive to standard therapies and have more persistent disease. Studies have examined the use of thyroid supplementation in the treatment of CU, with mixed results. Best treatment for this condition is daily antihistamines. See Allergist. ...Read moreSee 1 more doctor answer
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