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I had grapefruit, then took 10mg of cetirizine about an hour or so later. I had no idea grapefruit could interact with antihistamines. Am i in danger?
No.: There is a protein in grapefruit that can inhibit one of the systems in the body that metabolize drugs. So, this may increase the potency of certain family of drugs, by decreasing the breaking down of the drug in the body. The two antihistamines that were in this category have been removed from the market, so there is probably a small, but clinically insignificant, effect. Don't worry. ...Read moreSee 2 more doctor answers
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
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 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
Taking lethal over: Dose would do that. Lethal overdoses of antihistamines are rare. Are you considering taking an overdose of antihistamines? If so, please get help right away. You can use national suicide hotlines 24/7 at 1-800-suicide (1-800-784-2433) or 1-800-273 – talk (1-800-273-8255). If you have accidentally taken too many antihistamines please contact 1-800-222-1222 (poison control hotline). Take care. ...Read more
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
Is there such thing as antihistamine resistance? Seems like it becomes less effective the more I take it.
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