Famotidine Is A Powerful Anti-serotonin Drug, Can Even Treat Serotonin Syndrome

[Wendy B]

At a dose of 10mg - 20mg famotodine does not really reduce stomach acid much. The stomach protection turned out to be due to improved blood flow and somehow helping mucosa regenerate. You usually need at least 40mg famotidine daily to see a serious drop in stomach acid. The dose for healing ulcers is even higher - usually 40mg x 2 daily.
But the point valid and I don't think anybody is advising gobbling up famotidine for no reason. It's just another tool to be used judiciously as needed, which won't affect stomach acid much.

I haven't read all the pages of this thread...Reading is super hard for me due to medical situation. I don't know if i have an ulcer, but last week I started to get dull burn in (stomach? intestines? both?) plus increased bloating more than usual, gas and even more reduced motility. Was inquiring on RP FB group natural options for ulcers before reaching out to MD or ND and it was suggested a famotidine post somewhere here. I guess this is it..... So I tried pepcid yesterday after reading this post and do notice less histamine reaction (I started getting daily wicked histamine reactions after peating about a year, but have pre-existing sibo that wont go away with 2 rounds antibiotics), and also notice some better mood. Anyway, I see it says only take two weeks. I do have some wierd feeling in chest/(heart?) when i take it, fatigue, and slow urine stream with it, but I'm coping with these affects as they arent too bad. Is it possible to get some more feedback on taking this for potential ulcer? You say 40 - 80 mg needed for ucler healing. Why does pill box say only take for two weeks? Is it dangerous to take longer? What dosing for possible ulcer? I'm about 100 lbs. Very intolerant to most supps or meds, Lyme, exhaustion, sleep dep from post benzo withdrawl, peating almost two years with not much improvement - probably due to the sleep disorder. Thanks for any help!

 

[Braveheart]

Famotidine Repurposing for Novel Corona Virus Disease of 2019: A Systematic Review - Docwire News

Drug Res (Stuttg). 2021 Mar 23. doi: 10.1055/a-1397-6763. Online ahead of print.ABSTRACTBACKGROUND: COVID-19 caused by SARS-CoV-2 was declared as a global

www.docwirenews.com

 

[Daniil]

"Histamine H2-antagonists significantly elevated plasma histamine levels"

Oops, I don't think that's a good thing.

 

[cs3000]

I wanted to make this as a separate thread, given how important anti-serotonin chemicals for metabolism and how few of them are available OTC. It looks like our old friend famotidine is a powerful inhibitor of serotonin synthesis in the GI tract, and the mechanism of action is the H2 antagonism as other H2 antagonists of the same class also appear to lower serotonin.
If famotidine is indeed an inhibitor of serotonin synthesis then this may explain its effects on improving insulin sensitivity, treating schizophrenia, preventing GI fibrosis, improving glycogen storage, etc. All of these pathologies involve excess serotonin to some degree.
Thanks to user @Texon for the reference!

Interesting Properties Of The H2 Antagonist Famotidine

Famotidine-induced reversal of meperidine-related serotonin syndrome: a case report
"...Serotonin syndrome is an unexpected fatal adverse event related to serotonergic medication. This case report is the first report describing the possible treatment effect of famotidine on serotonin syndrome. Furthermore, this is the first case report of serotonin syndrome induced by meperidine alone in a patient with no previous history suggesting a susceptibility to serotonin syndrome. A 70-year-old male with no recent history of serotonergic drug use presented with severe serotonin syndrome following ureteroscopy, possibly due to postoperative meperidine administration. The patient's symptoms included hypertension, tachycardia, tachypnea, hyperthermia, myoclonus, diaphoresis, retching, nausea, agitation, and semicoma mentality with no pupillary light reflex. Symptoms began to subside immediately after the administration of intravenous famotidine for prevention of aspiration pneumonia, with mental and neurological symptoms showing improvement initially, followed by autonomic symptoms. This case report suggests that the histamine type 2 receptor antagonist famotidine may be an effective emergency treatment for serotonin syndrome."

Btw, inside that study they reference another one showing that H2 antagonism in the gut with other drugs similar to famotidine reduces serotonin levels. So, H1 antagonists, which are known to antagonize H2 in higher doses, should also reduce serotonin levels. Thus, drugs like cyproheptadine and Benadryl may be not only serotonin antagonists but serotonin synthesis inhibitors as well. A double-benefit for those already highly beneficial drugs.
Effects of eight-week treatment with histamine H2-antagonists or an antacid on plasma levels of histamine and serotonin in duodenal ulcer patients. - PubMed - NCBI
"...The effects of 8-week treatment with oral histamine H2-antagonists (ranitidine or cimetidine) or an antacid on plasma levels of histamine and serotonin were studied in duodenal ulcer patients. Histamine H2-antagonists significantly elevated plasma histamine levels, however, they markedly decreased serotonin concentrations by the 4th week of treatment. Antacid treatment similarly increased histamine levels without significantly affecting blood serotonin. It is concluded that changes in intragastric or intraduodenal acidity affect histamine release, as reflected by increased blood levels; serotonin secretion could be influenced by blocking histamine H2-receptors, possibly those located mainly in the gastrointestinal tract."

good stuff.

interesting one small study, 44% of autistic children treated with famotidine showed positive improvement in autism traits (elevated serotonin in autism connection)
https://link.springer.com/article/10.1007/s007020170059

also seeing as the serotonin syndrome case report suggests it worked acutely, and there's ~40% oral bio availability with peak in plasma within a few hours, dose he took then would be ~45mg orally, looks like it should have this effect from day 1

for some of the h1 anagonists being similar comment - loratadine h1 antagonist might be one, showed anti-serotonin effect Effect of loratadine on immediate and delayed type hypersensitivity reactions - PubMed

 

[Smelly5]

I dont understand why this medication isnt more popular (in this community).
I've had better results w this drug than any other including;
-Feeling of inflamation in upper abdommen gone while under the influence of the drug
-Acutely completely quelling my alllergic reaction to peanuts
-Improving mood, feeling very calm
-Lowering water retention
-Feeling like I have energy and no fatigue at all at the end of a work day (which is unusual for me)
-Regained ability to unfocus my eyes

Although, I haven't been able to find much more info on side effects and potential rebound of the substances it's altering. Can anyone shed light on this?

 

[cs3000]

I dont understand why this medication isnt more popular (in this community).
I've had better results w this drug than any other including;
-Feeling of inflamation in upper abdommen gone while under the influence of the drug
-Acutely completely quelling my alllergic reaction to peanuts
-Improving mood, feeling very calm
-Lowering water retention
-Feeling like I have energy and no fatigue at all at the end of a work day (which is unusual for me)
-Regained ability to unfocus my eyes

Although, I haven't been able to find much more info on side effects and potential rebound of the substances it's altering. Can anyone shed light on this?

there's a study that showed it created enhanced fungal growth in humans (from low acid environment). Candida overgrowth after treatment of duodenal ulcer. A comparison of cimetidine, famotidine, and omeprazole - PubMed 6 weeks taking, ph >4 = 16 of the 35 people had significant overgrowth at first which became 27 of the 35

so probably good to pair with something that helps restore stomach pH to keep protective effects

 

[Smelly5]

so probably good to pair with something that helps restore stomach pH to keep protective effects

Such as what?

 

[cs3000]

Such as what?

this vid has some info about stuff that works at least acutely but idk about baseline pH. i guess u could use spread out some of these throughout the day (in safe amounts not likely to cause harm). at least then countering the daytime pH rise for as long as they work for

View: https://www.youtube.com/watch?v=-J9JqmoXUTo

 

[Smelly5]

this vid has some info about stuff that works at least acutely but idk about baseline pH. i guess u could use spread out some of these throughout the day (in safe amounts not likely to cause harm). at least then countering the daytime pH rise for as long as they work for

View: https://www.youtube.com/watch?v=-J9JqmoXUTo

That bird is off her rocker. I'm not watching 40 minutes of her content LOL

 

[Mito]

I dont understand why this medication isnt more popular (in this community).

It seems fairly popular based on the number of positive studies posted on the forum, but maybe it would be more popular if it was available without titanium dioxide and dyes?

 

[cs3000]

there's a study that showed it created enhanced fungal growth in humans (from low acid environment). Candida overgrowth after treatment of duodenal ulcer. A comparison of cimetidine, famotidine, and omeprazole - PubMed 6 weeks taking, ph >4 = 16 of the 35 people had significant overgrowth at first which became 27 of the 35

so probably good to pair with something that helps restore stomach pH to keep protective effects

1 study showed 0.5mg/kg ~30mg famotidine increases pH over 4, to 4.8pH, & 60mg to 6.6pH


i was wondering how long the effect lasts for

https://www.cochranelibrary.com/central/doi/10.1002/central/CN-00073353/full

^ this one shows 0.15mg/kg in humans taken orally, so ~10mg, increases pH over 2.5

they said the effect sustains pH over 2.5pH for 4.5 hours (first 1.5 hours to get the pH effect so 6 hours) at these doses ~10mg - 40mg
but that's in children so i guess they eliminate it faster

this one says 40mg raises pH >4 for 12 hours https://accp1.onlinelibrary.wiley.com/doi/abs/10.1002/j.1552-4604.1987.tb02998.x?sid=nlm:pubmed

same here A comparison of the effects on intragastric acidity of bedtime or dinnertime administration of a once daily dose of famotidine - European Journal of Clinical Pharmacology dosing 6pm still had pH high at 8am

20mg through IV took 8-9 hours to go back <3.5pH THE COMPARATIVE EFFECTS OF SINGLE INTRAVENOUS DOSES OF CIMETIDINE, RANITIDINE, FAMOTIDINE, AND OMEPRAZOLE ON INTRAGASTRIC PH


* The effectiveness of gastric pH control with bolus famotidine versus cimetidine for stress ulcer prophylaxis in a surgical intensive care unit 20mg (orally?) The effective duration of action (percentage of time pH was >4) for each dose regimen was: cimetidine 200 mg, 1.4 hours; cimetidine 400 mg, 1.8 hours; and famotidine 20 mg, 4.8 hours

^ so by this 20mg in children sustains pH >2.5 for 4.5 hours. 20mg in adults sustains pH over 4 for 4.8 hours , a lot less than the 40mg dose. and 200mg - 400mg cimetidine raises pH >4 for a lot less time ~2 hours

probably still lower acidity than what's protective & good for digestion for some more hours after but far better timing at 20mg than 40mg.

 

[golder]

So what kind of Famotidine dose do you think we can use for seratonin antagonism that isn’t going to affect the stomach pH?

 

[cs3000]

So what kind of Famotidine dose do you think we can use for seratonin antagonism that isn’t going to affect the stomach pH?

0.1mg/kg didn't change gastric pH significantly so ~6mg famotidine The Effects of Preanesthetic Low Dose Famotidine on Gastric pH and Volume in Children.

lower dose than that as human equivalent in a mice study slowed calcification of a tendon a lot so it's probably active at that amount. but idk if that's effective for serotonin, dose in the OP study was injection & oral dose would be less bioavailable so ~50mg for that effect shown against serotonin syndrome i think

can't find the dose for the cimetidine study that showed lower plasma serotonin


bonus rabbit study on cimetidine & serotonin (injected rabbits with serotonin and cimetidine blocked the reduction of blood pressure & the induced bradycardia
INHIBITION OF SEROTONIN-MEDIATED CARDIOVASCULAR REFLEXES BY CIMETIDINE IN THE RABBIT

 

[cs3000]

There's a cool study about this in mice, showing effects of famotidine & cimetidine on neurotransmitters

Effect of cimetidine, ranitidine and famotidine on norepinephrine, dopamine and serotonin contents in different brain areas of mouse | Bulletin of Faculty of Pharmacy-Cairo University. 1996; 34 (1): 35-40 | IMEMR


The acute and subacute effects of histamine [H2] receptor antagonists [cimetidine, ranitidine and famotidine] on norepinephrine [NE], dopamine [DA] and 5-hydroxytryptamine [5-HT] contents have been studied in different brain areas of mouse; namely, cerebral cortex, thalamus and hypothalamus, midbrain as well as the area of medulla, pons and cerebellum.

The doses used were equivalent to the human therapeutic dosage. The results revealed that cimetidine [50, 100 mg/kg], ranitidine [19, 38 mg/kg] and famotidine [2.5, 5 mg/kg] caused significant increase in norepinephrine and dopamine contents in the most of the examined brain areas after single and twice daily 15 days administration.

It was shown that 50 mg/kg cimetidine decreased 5-HT content in thalamus and hypothalamus after 15-days administration. Increasing the dose to 100 mg/kg resulted into an increase in 5-HT content in the area of thalamus and hypothalamus and that of midbrain respectively after acute or subacute administration. It is probable that the changes in brain monoamines content observed may play a role in CNS adverse effect of H2-receptor antagonists.
@haidut


So Famotidine causes increase in dopamine, & not just 1 area of the brain but in most areas of the brain, by 15 days.

2.5mg/kg is ~12mg-15mg human dose. can't tell if they injected directly into the blood or through the stomach. it's one of those because they said the doses are equivalent to typical human doses. if its directly then the dose is probably a bit higher

& they found a paradoxical response on lowering serotonin with cimetidine (too much cimetidine actually increased serotonin ~500mg, [& maybe more of an effect on raising prolactin which it's also known for? Effects of H2-receptor antagonists on prolactin secretion: Specificity and mediation of the response 1.6 micromoles increased prolactin & 0.4micromoles inhibited prolactin ], <- dopamine inhibits prolactin , serotonin increases prolactin (600mg dose injected caused prolactin increase mediated by serotonin) , & human study 400mg injected raises prolactin Cimetidine effect of dopaminergic modulation of prolactin release in healthy women - PubMed

The relationship of cimetidine to 5-hydroxytryptamine tissue levels in stress ulceration in the rat - PubMed another one that showed prevention of increase in serotonin in stomach from stress (& ulcer) at 1g. (but these high doses raise serotonin in brain) but Effects of histamine and cimetidine on the levels of serotonin and 5-hydroxyindoleacetic acid in various parts of the digestive tract and in the blood and brain of rats - PubMed this showed slight increase of serotonin in stomach , high dose also increase in the jejenum. and no change in the blood or brain (odd)

1st study half dose 250mg cimetidine lowered serotonin in thalamus & hypothalamus.


interestingly dopamine drugs also heal peoples duodenal ulcers just as effectively Dopamine agonists prevent duodenal ulcer relapse. A comparative study with famotidine and cimetidine - PubMed which gives extra weight to famotidine being dopaminergic in humans

famotidine does not show raised prolactin at 20mg / 40mg injected Pharmacodynamics of famotidine in humans - PubMed so to me that goes with the first study (doesn't raise serotonin at these doses - stays dopaminergic)

 

[haidut]

There's a cool study about this in mice, showing effects of famotidine & cimetidine on neurotransmitters

Effect of cimetidine, ranitidine and famotidine on norepinephrine, dopamine and serotonin contents in different brain areas of mouse | Bulletin of Faculty of Pharmacy-Cairo University. 1996; 34 (1): 35-40 | IMEMR
View attachment 43966

The acute and subacute effects of histamine [H2] receptor antagonists [cimetidine, ranitidine and famotidine] on norepinephrine [NE], dopamine [DA] and 5-hydroxytryptamine [5-HT] contents have been studied in different brain areas of mouse; namely, cerebral cortex, thalamus and hypothalamus, midbrain as well as the area of medulla, pons and cerebellum.

The doses used were equivalent to the human therapeutic dosage. The results revealed that cimetidine [50, 100 mg/kg], ranitidine [19, 38 mg/kg] and famotidine [2.5, 5 mg/kg] caused significant increase in norepinephrine and dopamine contents in the most of the examined brain areas after single and twice daily 15 days administration.

It was shown that 50 mg/kg cimetidine decreased 5-HT content in thalamus and hypothalamus after 15-days administration. Increasing the dose to 100 mg/kg resulted into an increase in 5-HT content in the area of thalamus and hypothalamus and that of midbrain respectively after acute or subacute administration. It is probable that the changes in brain monoamines content observed may play a role in CNS adverse effect of H2-receptor antagonists.
@haidut


So Famotidine causes increase in dopamine, & not just 1 area of the brain but in most areas of the brain, by 15 days.

2.5mg/kg is ~12mg-15mg human dose. can't tell if they injected directly into the blood or through the stomach. if its directly then the dose is probably a bit higher

& they found a paradoxical response on lowering serotonin with cimetidine (too much cimetidine actually increased serotonin ~500mg, [& maybe more of an effect on raising prolactin which it's also known for? Effects of H2-receptor antagonists on prolactin secretion: Specificity and mediation of the response 1.6 micromoles increased prolactin & 0.4micromoles inhibited prolactin ], <- dopamine inhibits prolactin , serotonin increases prolactin (600mg dose injected caused prolactin increase mediated by serotonin)

The relationship of cimetidine to 5-hydroxytryptamine tissue levels in stress ulceration in the rat - PubMed another one that showed prevention of increase in serotonin in stomach from stress (& ulcer) at 1g. (but these high doses raise serotonin in brain) but Effects of histamine and cimetidine on the levels of serotonin and 5-hydroxyindoleacetic acid in various parts of the digestive tract and in the blood and brain of rats - PubMed this showed slight increase of serotonin in stomach , high dose also increase in the jejenum. and no change in the blood or brain (odd)

1st study half dose 250mg cimetidine lowered serotonin in thalamus & hypothalamus.

Thanks. Confirms some of the other studies I have seen. The reason I got interested in famotidine initially is that it was the only H2 antagonist that did not have side effects (at any dose) such as increased prolactin, anti-androgenic effects, increased cortisol, or increasing mortality in hospital patients. The other H2 antagonists, as confirmed by these studies as well, are at best inconsistent at lowering serotonin and often raise it.

 

[cs3000]

Thanks. Confirms some of the other studies I have seen. The reason I got interested in famotidine initially is that it was the only H2 antagonist that did not have side effects (at any dose) such as increased prolactin, anti-androgenic effects, increased cortisol, or increasing mortality in hospital patients. The other H2 antagonists, as confirmed by these studies as well, are at best inconsistent at lowering serotonin and often raise it.

aye looks good, that broad wound healing study you posted is nice too not just limited to the stomach so i bet this would be good for small intestinal / colon ulcers too. yeah i just read famotidine doesn't raise prolactin like the others , at least at 20mg and 40mg injected. so probably just dopaminergic without the added serotonin that the higher doses of the others can give
cheers for the threads & podcasts lots of informative stuff

 

[Inaut]

Where can I buy a clean famotidine product in Canada? Locally?

 

[tastyfood]

Where can I buy a clean famotidine product in Canada? Locally?

+1 I have the ones from the Pepcid brand but it was way too many additives. The one time I took it, it hurt my stomach so much.

 

[japanesedude]

Famotidine does something to my eyes. after taking 10-20mg for a week I started to experience eye problems. I felt little pressure around my eyes and my vision was declined.

 

[cs3000]

Famotidine does something to my eyes. after taking 10-20mg for a week I started to experience eye problems. I felt little pressure around my eyes and my vision was declined.

ive seen a report of this happening in rare cases , probably best for u to avoid it completely