Antihistamine OD - is that a thing?

[paltatomate]

I just took an antihistamine and then remembered I already took one about three hours ago. I never gave this a thought, but somehow I got curious if there is "too much" and tried to Google it.

All I got was that 10mg of loratadine is enough for one day and people shouldn't take more than that. There's either no information about possible side effects, or a warning to call emergency services.

Anyone who can clarify this for me?
I'm fine, btw.

 

[Skorpio]

Usually the issue is with excess antimuscarinic activity causing a deleriant trip. This is an issue with 1st gen antihistamines that can get into the brain (diphenhydramine and friends). Loratidine gets pumped out of the brain, and even then is pretty weak as an antimuscarinic, so you should be fine and dandy.

You might feel a slight bit more sedated than a normal dose, but it should be quite subtle compared to even a half dose of diphenhydramine.

 

[someguyontheinternet]

Some can also cause abnormal heart rhythms, such as long QT by interfering with potassium chan els, but that's usually at higher doses. There are also some that got pulled from the market for causing them at therapeutic doses

 

[MedicinalUser247]

I don't recommend this, but in the past I've taken up to 24 tablets of 25mg.s of Diphenhydramine to trip. I found out it was a horrible thing to trip off of. If you can try to find a good hallucinogen and try not to trip off that antihistamine crap.

 

[deficiT]

Ns&pd ----- > od

 

[paranoid android]

At that dose you should be fine its not a anticholinergic anyway

 

[deficiT]

Yeah that's not an overdose

 

[deficiT]

Don't want to take a bunch of those, but you're fine this time

 

[deficiT]

I just took an antihistamine and then remembered I already took one about three hours ago. I never gave this a thought, but somehow I got curious if there is "too much" and tried to Google it.

All I got was that 10mg of loratadine is enough for one day and people shouldn't take more than that. There's either no information about possible side effects, or a warning to call emergency services.

Anyone who can clarify this for me?
I'm fine, btw.

In the future just type in "substance +, ld50" in the search engine

 

[paranoid android]

Don't want to take a bunch of those, but you're fine this time

My brother took 10 of them one time for his allergies. Besides some gi symptoms he didnt get any real side effects

 

[paltatomate]

I don't recommend this, but in the past I've taken up to 24 tablets of 25mg.s of Diphenhydramine to trip. I found out it was a horrible thing to trip off of. If you can try to find a good hallucinogen and try not to trip off that antihistamine crap.

I take 10mg when I feel allergy symptoms. Watery eyes, running nose, sinus issues. Normally the symptoms go away and I forget about antihistamines or allergies and that's it.
But today the symptoms stayed, and that's why I took another one without really thinking.

By now I'm convinced the symptoms are not caused by an allergy, but by an upcoming cold

Other than body ache and an overall feeling of weakness I'm fine (no heart issues or something). So I guess I worried for nothing.

Thanks guys!

 

[Skorpio]

There are also some that got pulled from the market for causing them at therapeutic doses

The story of terfenadine is a classic example of the impact of genetics on a drug. Terfenadine was an early non-drowsy antihistamine.

It was a prodrug for the antihistamine fexofenadine, converting both rapidly and fully upon first pass metabolism. This was good (for most people), because terfenadine blocks the hERG potassium channel, causing deadly arrythmias (blockade of this channel is the death knell of many drugs).

For most people, terfenadine was a safe and well-tolerated drug. Unfortunately, for those with missing or dysfunctional metabolic enzymes, the terfenadine isn't metabolized to fexofenadine, and caused fatal arrythmias. This effect was rare enough to not be detected in even stage III clinical trials, only being detected after people started dropping dead.

Terfenadine was then shelved and replaced with fexofenadine and everybody lived happily ever after (though the company that developed fexofenadine was a company known for patenting interesting things developed by others, and some patent lawyers likely lost their jobs after missing that one).

 

[emkee_reinvented]

The story of terfenadine is a classic example of the impact of genetics on a drug. Terfenadine was an early non-drowsy antihistamine.

It was a prodrug for the antihistamine fexofenadine, converting both rapidly and fully upon first pass metabolism. This was good (for most people), because terfenadine blocks the hERG potassium channel, causing deadly arrythmias (blockade of this channel is the death knell of many drugs).

For most people, terfenadine was a safe and well-tolerated drug. Unfortunately, for those with missing or dysfunctional metabolic enzymes, the terfenadine isn't metabolized to fexofenadine, and caused fatal arrythmias. This effect was rare enough to not be detected in even stage III clinical trials, only being detected after people started dropping dead.

Terfenadine was then shelved and replaced with fexofenadine and everybody lived happily ever after (though the company that developed fexofenadine was a company known for patenting interesting things developed by others, and some patent lawyers likely lost their jobs after missing that one).

Somewhat like the Phenacitin Paracetamol thing. Paracetamol was the metabolite responseable for the anti-pyretic and presumeable pain killing effects, even discovered before Phenacitin. Just read Paracetamol pain killing effects are no better then placebo?

Phenacitin was poisonous and lead to deaths.
A minority of the time the acetyl group is removed from the amine, producing carcinogenic p-phenetidine.

My mom still has a ancient tube with wafer like pills a death family member left, an real old med containing a.o. Phenacitin. Nourityn brand name i posted the ingredients on here.

 

[Jnowhere]

I don't recommend this, but in the past I've taken up to 24 tablets of 25mg.s of Diphenhydramine to trip. I found out it was a horrible thing to trip off of. If you can try to find a good hallucinogen and try not to trip off that antihistamine crap.

I will not get into the details, other than to say, if you try getting high or tripping off Benedryl, you are not going to have any fun. Miserable and probably dangerous, Benedryl is not a recreational drug.