Fatigue on Foundayo™

The fatigue row and its footnote

Table 1 in section 6.1 draws on Trials 1 and 2, the ATTAIN-1 and ATTAIN-2 studies: adults living with obesity or overweight, some of them with type 2 diabetes, treated once daily for up to 72 weeks ^[1]. The fatigue row carries a footnote saying it includes other related terms, so it captures more than the single word fatigue. The label does not list which terms were grouped.

The Medication Guide puts “feeling tired” among the most common side effects ^[2]. The European medicines committee adopted a positive opinion on 15 October 2026, but there is no EMA product information yet and so no EU frequency for tiredness; Health Canada’s database has no Foundayo™ or orforglipron entry ^[3][4].

A steady climb with the dose

Many rows in the table jump at the first dose and then level off. Fatigue rises one or two points at each step, ending at more than twice the placebo rate on 17.2 mg ^[1]. Only nausea, diarrhea and vomiting also rise at every step; constipation, indigestion and bloating peak at 9 mg instead.

The absolute numbers are still modest. Even at the top dose, fewer than one in ten people reported fatigue at any point in the trials, and four in a hundred did so on placebo.

It also helps to know who was in the pool. The average age was 49; half had high blood pressure, almost half had abnormal blood fats, 31% had type 2 diabetes and 11% had obstructive sleep apnea at the start ^[1]. Tiredness in such a group is not rare to begin with, which the placebo figure reflects.

Why the registry numbers come out lower

Each ATTAIN study posted results on ClinicalTrials.gov, listing non-serious events that reached 5% in at least one group ^[5][6]. The registries use single standard terms, so their “fatigue” leaves out the related terms the label folds into its row. Neighbouring terms such as asthenia or malaise do not appear in the ATTAIN lists at all, which means they stayed under 5% in every group, not that nobody had them.

Two diabetes trials, ACHIEVE-1 and ACHIEVE-5, posted every event and show both fatigue and asthenia, the medical word for weakness ^[7][8]. The US label does not cover type 2 diabetes, and these trials used their own doses. All four trials below were double blind.

What the four trials show together

• In both ATTAIN trials, where the 6, 12 and 36 mg trial doses equal Foundayo™ 5.5, 9 and 17.2 mg, single-term fatigue was higher on orforglipron than on placebo, by a few percentage points ^[1][5][6].
• The tidy step-by-step climb of the label row is less regular trial by trial: in ATTAIN-2 the middle dose had the highest figure ^[6].
• In ACHIEVE-1 the direction reversed, with placebo highest; in ACHIEVE-5 fatigue and asthenia were both more frequent on the two upper doses ^[7][8]. With one to six cases per group, these smaller trials cannot settle the question.
• The published ATTAIN-1 results, from a randomised trial, name stomach effects as the most common adverse events and do not single out fatigue in the abstract ^[9].

Possible explanations, from best supported to untested

Label findings that can feel like tiredness. Foundayo™ can lower blood sugar: in the trial of adults with type 2 diabetes, 2% on the tablet had glucose below 54 mg/dL against 0.2% on placebo, and 7% of those also taking a sulfonylurea reported hypoglycemia; in adults without diabetes it was recorded in 0.6% against none on placebo (sections 5.5 and 6.1) ^[1]. The Medication Guide’s list of low blood sugar signs includes weakness, drowsiness, confusion and dizziness ^[2]. Hypotension was reported in 2% on Foundayo™ against 0.5% on placebo, and in 4% of treated people who also took blood pressure medicines ^[1]. Section 5.4 links dehydration from stomach reactions to kidney injury ^[1], and Cleveland Clinic lists dehydration among causes of fatigue ^[11].

Suggested but not measured. Section 12.2 says Foundayo™ reduces food intake, probably through lower appetite, and that more fat than lean mass is lost ^[1]. MedlinePlus lists malnutrition among conditions that come with fatigue ^[10]. The label does not connect eating less with tiredness, and no source reviewed here has measured that link for orforglipron, so it is a question to raise rather than an answer.

Unknown. The label gives no mechanism, timing, severity or stopping figure for fatigue itself ^[1].

Everyday causes worth ruling out

MedlinePlus describes fatigue as common and usually not due to serious disease, and both it and Cleveland Clinic list causes a clinician may look for ^[10][11]:

• Anaemia, iron deficiency, and low vitamin D or vitamin B12 ^[10][11].
• A thyroid gland that is underactive or overactive; Cleveland Clinic calls hypothyroidism a common cause ^[10][11].
• Sleep disorders such as insomnia and obstructive sleep apnea, which 11% of people in the label’s trials had at the start ^[1][10].
• Depression, grief, anxiety and stress ^[10][11].
• Diabetes, heart, kidney or liver disease, and infections including COVID-19 ^[10].
• Medicines such as antihistamines, blood pressure medicines, sleeping pills, steroids and diuretics, and alcohol ^[10].

What the sources suggest

MedlinePlus’s home-care tips are general: enough sleep, a healthy and balanced diet with water through the day, regular exercise, ways to relax, a manageable schedule, and avoiding alcohol, nicotine and drugs ^[10]. It also says stimulants, caffeine included, do not treat fatigue effectively and can make it worse once stopped ^[10]. Cleveland Clinic adds regular sleep and wake times and avoiding caffeine, screens and exercise just before bed ^[11].

Both sources send the rest to a clinician. MedlinePlus suggests discussing whether a vitamin supplement might help rather than starting one on your own, and Cleveland Clinic suggests asking whether a medicine you take could be causing the tiredness ^[10][11]. On Foundayo™, that conversation can include the latest dose step, any diabetes medicines and how much you have been eating and drinking.

What a clinician may check

MedlinePlus describes tests a provider may order: blood tests for anaemia, diabetes, inflammation and infection, kidney, liver and thyroid function tests, and a urine test ^[10]. A few weeks of notes help: when the tiredness started relative to a dose step, how you slept, what you ate and drank, and glucose readings if you test. The label asks clinicians to monitor blood glucose in people with diabetes and asks patients to report signs of hypoglycemia (sections 5.5 and 17) ^[1].

Foundayo™ is a trademark of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Eli Lilly and Company.

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