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Side Effect: Diarrhoea

11 replies9 peopleFeb 8, 2026☆ Follow
Summary

Is diarrhea a normal side effect of retatrutide and how should dosing be adjusted if it occurs?

Users report watery diarrhea as a recognized effect of retatrutide that often appears after dosing and can coincide with rising blood levels around week 3-4. Several lowered their dose to 1 mg or 1.5 mg and planned slower increases, while others noted symptoms eased after a few weeks or with Imodium. Peak levels build gradually due to the long half-life, so side effects tend to be strongest in the first one to three months.

What this discussion establishesStill open

Whether the episode was caused by the drug or by something else such as food remains unsettled for the original poster.

Nothing here is advice.

11 replies · 9 people
PlainHarbour37archiveopening postFeb 8

Still on the 2 mg dose and had strong watery diarrhea last week that slowly went away. Not sure if it was from some bad vegetable or actually from Reta, since it felt exactly like food poisoning. Has anyone else run into this? Does it line up with the usual side effects? Should I drop the dose or maybe skip a week?

AmberMarble84archiveFeb 8

People often mention this reaction occurring. The problem began immediately after taking it so I assumed it came from reta. I therefore decreased to a single milligram.

PlainHarbour37archiveFeb 8
↳ replying to @AmberMarble84

It happened in week 3. Weekly 2 mg doses so far.

AmberMarble84archiveFeb 8
↳ replying to @PlainHarbour37

I would suspect Reta. It builds up in your system.

CopperSignal27archiveFeb 8

It's odd how this influences intestinal movement since it might lead to either blocked bowels or loose ones. With steady amounts the highest concentrations build after a month so they rise a little weekly and hit max shortly following each intake. This behaves unlike most substances due to gradual uptake and extended duration in the body. Reactions seem tied to those maximum concentrations. I think lowering back to a smaller amount temporarily before stepping up gradually makes sense. Typically digestive troubles are strongest early on and ease later for many users with slower increases helping to lessen them.

ClearMeadow20archiveFeb 9

Been using this for eighteen weeks now. Just raised the amount from three milligrams every five days up to five, and the loose stools began right after. Made a switch to a new batch around the same time. Got a few ideas on the cause, though the anti-diarrheal medication appears to ease things. Hoping this is only temporary as my body adjusts.

SharpCinder28archiveFeb 9

Been checking out some stuff while in the restroom lately about typical reactions. Started at five milligrams weekly and dealt with loose bowels for a few days following each shot. Went up to ten milligrams the other night and woke up feeling pretty rough with lots of perspiration unless the air conditioning was cranked way down, plus the usual loose bowels, belly cramps, and a mild head throb. The belly cramps stand out as the worst part. Has anyone else noticed chunks of food that didn't get broken down properly showing up in their output while on this med? Could tie into shifting what I eat toward more greens and leafy things, but it's strange seeing vegetable pieces come out, especially around the two-day mark after a shot. The reactions seem to kick in strongest about two days later for some reason. On the topic of beginning amounts, does it make sense for folks to kick off at one milligram? Probably not, even if there are rare cases. Two point five milligrams counts as the entry level amount, going up to a top of fifteen which is much higher. Some mix-up might come from how results vary early on. Wondering if a different option like the newer compound could suit me better instead. Been on the current one for over three months now but keep hitting snags that prevent reaching a useful level. Got up to five milligrams once a week before running into severe loose bowels and trouble sleeping around the middle of the week.

SteadyQuill55archiveFeb 9
↳ replying to @SharpCinder28

I can't figure out why people seem so eager to share accounts of their defecations. It seems that in every society and throughout history there are clusters of folks who insist on detailing their bowel movements.

WryBramble37archiveFeb 9

This side effect appeared for me in week two on the first medication and then came back during week two on the follow-up one. It was just a single occurrence. I'll push ahead for one more week to check if it goes away.

LevelAlder78archiveFeb 9

At the very start that happened briefly over several days and perhaps once after raising the amount yet constipation has been the main problem for me.

SharpCinder28archiveFeb 9
↳ replying to @SteadyQuill55

I notice that water-soluble fiber products can ease things as well, even if it feels backwards because they're commonly taken to address the opposite problem. Besides helpful bacteria options, one debated herbal choice stands out for longer use since its subtle pain-reliever-style actions tend to calm the lower digestive tract. My pharmacist stressed loose stools as the main reason folks quit the medication altogether. Plenty of people using these hormone-based treatments go through the most intense loose stools of their lives, above all those who already dealt with irritable bowel trouble in the past.

BrightLantern56archiveFeb 9
↳ replying to @PlainHarbour37

It happens fairly often by the fourth week once the initial dose has been given because the amount in the system tends to climb and then level out. More problems could show up now and in the coming days. I thought about returning to a smaller amount like one or one point five and remaining there for around thirty days. After that the body has time to settle so a slow move upward becomes possible. My own increase might need to happen more gradually. Another choice was continuing without changes and just managing until things settle on their own though that was not what I wanted. Paying close attention to meals that set things off helped me too since rich or greasy items created issues at the beginning. Remaining on the higher amount worked if those were skipped. It might have been something from food that went bad but probably not.

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