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Doctor insights on: Can I Take More Than One Antihistamine

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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?

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?

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. ...Read more

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

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

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

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

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

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 more

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Can I take one antihistaminic at moorning and another one at nigt? For alergic reactions.

Can I take one antihistaminic at moorning and another one at nigt? For alergic reactions.

Yes but...: Antihistamines can be taking twice a day safely if required but there are other treatments available. If by allergic reaction you are referring to seasonal allergies, the gold-standard therapy is daily nasal steroid sprays and/or antihistamine nasal sprays. Nasal saline rinses, avoidance measures, and if refractory to treatment, allergy shots can also be helpful. See an Allergist for more details. ...Read more

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Hi. I took three antihistamines by mistake when I was told to take only one at night. Is this dangerous? Each tablet is 120 gms

Hi. I took three antihistamines by mistake when I was told to take only one at night. Is this dangerous? Each tablet is 120 gms

Likely Ok: Antihistamines have a high safety margin although the older antihistamines may have more side effects. It is unusual to have mistakenly taken 3 pills when most medication is based on 1 pill. You will have to be more careful in the future since other medications may not be as forgiving. ...Read more

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Is it safe to take another 24-hour zyrtec (cetirizine) antihistamine if there's still about 8 hours left before the previous one wears off?

Is it safe to take another 24-hour zyrtec (cetirizine) antihistamine if there's still about 8 hours left before the previous one wears off?

Follow dosing: It's best to adhere to the dosing recommended. It would be hard to overdo it with the zyrtec (cetirizine), the way you are suggesting, but it begs the question- how well does the rx work, if you want more before the proper dosing interval? I would think you need to talk with your doctor about other options to achieve safe allergy control. Sometimes more than one rx is necessary. ...Read more

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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?

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?

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, ...Read more

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Should one avoid pregnancy if they have to take inhalors, and strong antihistamines, and omeprazole and nasonex (mometasone) regularly?

Change the meds: It's unusual to have to avoid pregnancy altogether because of medications that you take. However, commonly it's recommended to change the meds at least temporarily during the pregnancy to avoid potential problems with the fetus. You should meet with an obstetrician before you get pregnant to discuss this. ...Read more

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Can an 18 lb. One-year old take pediacare (acetaminophen) with equate (antihistamine)? He has a fever and runny nose.

Can an 18 lb. One-year old take pediacare (acetaminophen) with equate (antihistamine)? He has a fever and runny nose.

Yes: According to the weight-based guidelines. The Acetaminophen is for fever and pain, the antihistamine would be to dry up secretions. Always clear these medications with your pediatrician prior to starting. ...Read more

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Would I benefit from imatrex as to just taking tylenol for my migraines? Usually behind one eye, zig zag around eyes, nauseated, throwing up at times. Can not take antihistamines, or OTC cough meds. Gives me heart palpatations. Although I do use Alaway an

Would I benefit from imatrex as to just taking tylenol for my migraines? Usually behind one eye, zig zag around eyes, nauseated, throwing up at times. Can not take antihistamines, or OTC cough meds. Gives me heart palpatations. Although I do use Alaway an

Yes: Tylenol (acetaminophen) does not really work that well for migraine and thus Imitrex would likely be far more effective. The earlier the better. Sometimes adding a NSAID may provide added benefits. If nausea prevents you from swallowing Imitrex, ask for a nasal spray version. ...Read more

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When should you take an antihistamine?

Multiple reasons: Depending on the type of antihistamine used they can be used to treat things such as allergy symptoms, nausea, dizziness, motion sickness, anxiety, itching, and difficulty sleeping. ...Read more

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What is the best time to take an antihistamine?

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

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I am about to take an antihistamine for the first time but my friends tell me to use it before bedtime. Will I still feel the effects the next day?

Depends on the med: Some antihistamines are more sedating than others. Medications like Benadryl (diphenhydramine) can definitely cause sedation. Newer antihistamines like Allegra and Claritin are non-sedating and Zyrtec is sedating in roughly 10-20% of patients. ...Read more

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Is it ok to take antihistamines with?

With what?: If you are thinking about drinking alcohol, do not do it. Antihistamines might potentiate the effect of alcohol. ...Read more

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I am allergie to antihistamine, can I take pepid?

I am allergie to antihistamine, can I take pepid?

Yes: Antihistamine blocks h1 receptors, while Pepcid (famotidine) blocks h2 receptors, however if u r in doubt of taking any medicine: pls go to any hospital, sit in the er waiting area, adminster the medicine, wait for about an hour, any serious allergic reaction would appear in the 1st hr, god forbids, then u r in the very place u want to be, pls excercise caution with multiple meds as u r on an anticoagulant. ...Read more

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