Question 1

can you take generic multi symptom night time medicine with night time thera-flu? i don't usually get drowsy from just one dose of antihistamine. i have adhd so it's hard for me to get sleepy from that. so is it okay to take both?

Accepted Answer

No: Those preparations contain multiple drugs similar to thera-flu, the problem isn't with antihistamines only, other components could interact, or interact with whatever medicines you are on or if you are under treatment for adhd, please consult your doctor and read the labels carefully, good that you asked , always exercise caution with multiple medications,

Question 2

what is the highest dosage of antihistamine that one person can take at one time?

Accepted Answer

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.

Question 3

how long will it take for prolactin levels (17.5 in male) to drop after discontinuing high doses of antihistamine for three consecutive months that caused elevated numbers? will hair stop shedding?

Accepted Answer

If it was: Due to the antihistamine, which a doubt, it should be relatively quickly over days. Also, it is unlikely that that is the cause of your hair loss. Check w/your doctor for other explanations for all of your concerns.

Question 4

is it safe to take an antihistamine like zyrtec daily for my dermatographia? will i need to increase the dose over time?

Accepted Answer

Dermatographia: is usually a "lifetime" condition. Antihistamines are sometimes effective and there are new developments  in the treatment of eaosinophils ( first "cousins" of mast cells the cells felt to be involved in the condition) Hope this is helpful!

Dr Z

Question 5

is it bad to take an antihistamine during a cold, i.e. does suppressing mucus make the cold last longer?

Accepted Answer

No value: Antihistamines have no value in the treatment of viral illnesses.

Question 6

when should you take an antihistamine?

Accepted Answer

For allergies: Antihistamines help the most with sneezing, watery drainage, and itching which are often seen with allergies. Older antihistamines (like benadryl) can make people sleepy and should be used with caution; newer antihistamines (like Claritin (loratadine) & allegra) are less likely to be sedating. Because of their drying effect, some doctors recommend avoiding antihistamines during a respiratory infection.

Question 7

what is the best time to take an antihistamine?

Accepted Answer

Any time: You can take antihistamines any time of the day.Take them same time of day everyday.

Question 8

how many milligrams of antihistamine can a person take at one time?

Accepted Answer

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.

Question 9

is there such thing as antihistamine resistance? seems like it becomes less effective the more i take it.

Accepted Answer

Drug Resistance: Tachyphylaxis: Rapidly decreasing response to a drug or physiologically active agent after administration of a few doses. Try a different antihistamine and that should work for you.

Question 10

i know it is not recommended to take more than one antihistamine pill per 24 hours, but some only last ~8 hours. which ones lasts for 24 hrs?

Accepted Answer

Xyzal (levocetirizine) and Clarinex: From experience some of the newer antihistamines such as Xyzal (levocetirizine) and Clarinex seem to be effective for longer time periods. Most antihistamines however peak in effectiveness in the first few hours and start to wear off after 12-15 hours.

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Doctor answers about:

What is the highest dose of antihistamine I can take

A member asked:

Can you take generic multi symptom night time medicine with night time thera-flu? i don't usually get drowsy from just one dose of antihistamine. i have adhd so it's hard for me to get sleepy from that. so is it okay to take both?

A member asked:

What is the highest dosage of antihistamine that one person can take at one time?

A member asked:

How long will it take for prolactin levels (17.5 in male) to drop after discontinuing high doses of antihistamine for three consecutive months that caused elevated numbers? will hair stop shedding?

A member asked:

Is it safe to take an antihistamine like zyrtec daily for my dermatographia? will i need to increase the dose over time?

A member asked:

Is it bad to take an antihistamine during a cold, i.e. does suppressing mucus make the cold last longer?

A member asked:

When should you take an antihistamine?

A member asked:

What is the best time to take an antihistamine?

A member asked:

How many milligrams of antihistamine can a person take at one time?

A member asked:

Is there such thing as antihistamine resistance? seems like it becomes less effective the more i take it.

A member asked:

I know it is not recommended to take more than one antihistamine pill per 24 hours, but some only last ~8 hours. which ones lasts for 24 hrs?

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