General Question

richardhenry's avatar

Does antihistamine have any side effects if you take above the recommended dosage for extended periods of time?

Asked by richardhenry (12638points) June 10th, 2008

I get hay-fever sometimes, and occasionally take 20mg (works perfectly) instead of the recommended 10mg (doesn’t do much).

Are there any side effects to taking an increased dosage? I tend to do it for a three to four week period once a year.

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13 Answers

gailcalled's avatar

Read the package. ZZZZZ

shilolo's avatar

Can you specify which antihistamine? Based on the dosage, I would guess claritin, but then, I’m not 100% sure. There are potential side effects to increasing the dosage, for sure. For one, the so-called non-sedating anithistamines can be sedating, in higher doses. Zyrtec for example is sedating to a lot of people even at the recommended doses. Headache is a known side effect as well.

One thing to keep in mind (and I know this wasn’t your question), is that during hay fever season, you would do better to take a nasal steroid (needs a prescription) than taking an antihistamine. Studies show that nasal steroids are superior to antihistamines for prevention of symptoms. Plus, as the old saying goes, “an ounce of prevention is worth a pound of cure.”

judochop's avatar

rapid heart rate known as tachyacardia, liver damage, insomnia, anxiety, weight loss, gum disease, congestion rebound, sinus infection. These are some.

shilolo's avatar

FYI, the side effects listed by judochop are either extremely rare, or, not associated with antihistamines. I have seen hundreds to thousands of patients taking antihistamines of various “flavors”, and I have not once observed those side effects.

steelmarket's avatar

Talk to your doc about taking two different kinds of antihists. I take Allegra plus a nasal steriod, now have better control over my allergies than any time in my life.

shilolo's avatar

Technically, a nasal steroid is not an antihistamine. It reduces the amount of inflammation, thus lowering the amount of toxic products, including histamine, that are released as a consequence of allergen-mediated stimulation of mast cells.

Lightlyseared's avatar

My twopence would be increased risk of gastointestinal upsets. (It’s my stock answer for drug side effects when you don’t know you).

I agree whith shililo though I find a steroid nasal spray is faster acting and more effective (and in the UK you can get it OTC)

gailcalled's avatar

And my thruppence is that Shilolo is our beloved and unique MD. We bow.

judochop's avatar

I like Basel steroids. I can no longer take anti’s due to rapid heart rate and sleeplessness that occurs but yes from what my doctor has said it is very, very rare.

richardhenry's avatar

Thanks for the helpful responses, I’ll speak to my GP. I’m on Cetirizine Dihydrochloride, manufactured by a UK company called TEVA UK Limited.

Seesul's avatar

@rh; That’s generic for Zyrtec here in the US. In Canada, it goes under the brand name Reactine.

Shilolo: Zyrtec was the only one that didn’t make me drowsy, and it also helped my headaches because it works for 24 hours and I don’t wake up with a stuffy nose. I use Flonase as well, because one without the other didn’t work for me. I’m kind of backwards, though, and the exception rather than the rule. At least I’m able to live comfortably now. and not sneeze my head off. With all of this smoke now, it’s a challenge, though. The latest dry lightening fire is only a few miles from my house. it’s shelter in place time.

shilolo's avatar

@seesul. Glad that zyrtec could help, but I have found in practice that a lot of people need to take it at night so as to not feel sleepy during the day. There are other options to antihistamines and steroids. You should speak with your doc and/or get a referral to an allergist.

scamp's avatar

Here is some more info on the medicine you are taking richardhenry.

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