Allergy, not rash, is what the label covers
Foundayo™ is a once-daily orforglipron tablet, a GLP-1 receptor agonist that the label does not describe as a peptide [1]. Its Warnings and Precautions include serious hypersensitivity reactions, such as anaphylaxis and angioedema, reported with GLP-1 receptor agonists [1]. If a reaction occurs, the label says to seek medical attention promptly and stop the tablet. It also asks for caution in anyone who has had anaphylaxis or angioedema with another GLP-1 medicine, because it is unknown whether they would react to Foundayo™ [1].
| Source | Entry | Comparison or context |
|---|---|---|
| US Prescribing Information, section 6.1 [1] | Hypersensitivity reactions, including anaphylactic reaction: 0.5% | Placebo 0.3% (Trials 1 and 2) |
| US Prescribing Information, sections 4 and 5.6 [1] | Contraindicated after a serious allergy to orforglipron or an ingredient | Stop and seek help if a reaction occurs |
| US Prescribing Information, section 6.2 [1] | Anaphylaxis and angioedema with GLP-1 receptor agonists | Post-approval reports; frequency unknown |
| US Medication Guide [2] | Severe rash or itching as a sign of serious allergy | Plain rash not on the common side-effect list |
| European Medicines Agency [3] | Positive CHMP opinion, 15 October 2026; no EU product information available yet | No section 4.8 band |
| Health Canada [4] | No Drug Product Database entry | No monograph |
Skin events in the trial registries
The ATTAIN weight trials posted only events affecting at least 5% of a group, and no skin term reached that level. Four smaller trials posted every event; most were in type 2 diabetes and used trial doses. Their skin entries are summarised below.
| Trial [source] | Comparison group | Orforglipron groups, low to high dose |
|---|---|---|
| ACHIEVE-1, double blind [5] | Placebo: rash 0, itching 3, hives 0 of 138 | Rash 0, 1, 1; itching 0 in each; hives 1, 0, 0 |
| ACHIEVE-5, double blind [6] | Placebo: rash 1, itching 2 of 140 | Rash 0, 0, 1; itching 0, 1, 2 |
| ATTAIN-J, double blind [7] | Placebo: rash 0, hives 2 of 60 | Rash 1 in each group; hives 1, 0, 3; itching 4 of 61 on the lowest dose |
| ACHIEVE-2, open label [8] | Dapagliflozin: rash 1, hypersensitivity 1 of 240 | Rash 3, 0, 0; itching 2, 0, 4; hypersensitivity 0, 3, 0 |
What the skin numbers add
- Skin events were scattered across groups, with no steady rise by dose and similar counts on placebo or dapagliflozin. Itching was, for example, more common on placebo than on orforglipron in ACHIEVE-1 [5].
- Group sizes of 60 to 240 mean one or two extra cases can swing a percentage a lot, so these tables cannot show a small increase in risk.
- The label’s figure of 0.5% against 0.3% for hypersensitivity comes from more than 4,000 people and is the better guide to allergy risk [1].
- None of these sources describes what the rashes looked like or how they were treated.
Why a rash might happen, and why it often has another cause
Supported by the label: an immune reaction to orforglipron or to one of the tablet’s other ingredients [1]. The inactive ingredients include copovidone, crospovidone, magnesium stearate, microcrystalline cellulose and sodium carbonate, and the coating contains polyethylene glycol, polyvinyl alcohol, talc, titanium dioxide and, depending on the strength, iron oxides [1][2]. Bringing this list to an allergist or pharmacist is useful if you have known excipient allergies.
Not supported: there is no evidence in the label or registries that orforglipron causes a non-allergic rash through some other mechanism. Unlike injectable GLP-1 medicines, a tablet has no injection site, so the injection-site reactions in those labels do not apply here.
General knowledge: MedlinePlus explains that most rashes come from skin inflammation, often from something the skin has touched, and that hives are frequently triggered by foods, medicines, insect bites, stress, heat or sweating, or appear with no cause at all [9][10].
Common non-drug causes
MedlinePlus lists these among frequent causes of rashes and hives [9][10]:
- Contact dermatitis from soaps, detergents, cosmetics, latex, rubber or dyes in clothing.
- Eczema, psoriasis and seborrhoeic dermatitis.
- Infections such as shingles, impetigo and viral illnesses.
- Insect bites and stings, pollen and pet dander.
- Foods such as shellfish, fish, nuts, eggs and milk.
- Cold, sun, heavy sweating, exercise and emotional stress.
What general sources suggest
For a simple rash, MedlinePlus suggests gentle cleansers, warm rather than hot water, patting the skin dry, leaving it open to the air and stopping any recently added cosmetic or lotion [9]. For hives, it suggests avoiding hot baths and tight clothing [10]. It mentions non-prescription hydrocortisone cream and oral antihistamines for itching [9][10]; a pharmacist can say whether they suit you, and the Foundayo™ label notes that the tablet can affect how other oral medicines are absorbed [1].
MedlinePlus also says to contact your provider about a rash when you are taking a new medicine, and not to stop or change any medicine without that conversation [9]. The exception is a serious allergic reaction, where the Medication Guide asks you to stop Foundayo™ and get help straight away [2].
Points specific to Foundayo™
Because Foundayo™ is taken every day, a reaction can appear after any dose, including after a dose step, when the tablet strength and its coating colour change [1]. Noting the date, the strength you were on and a photo of the skin helps your clinician decide whether the timing fits.
If you have previously reacted to another GLP-1 medicine with anaphylaxis or angioedema, tell your prescriber before starting; the label asks for caution in that situation [1].
Foundayo™ is a trademark of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Eli Lilly and Company.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Swelling of the face, lips, tongue or throat, wheezing, or difficulty breathing or swallowing | Stop the tablet and call emergency services | Emergency | Foundayo™ Medication Guide [2], MedlinePlus [11] |
| Severe rash or itching with fainting, dizziness or a very rapid heartbeat | Stop the tablet and get medical help right away | Emergency | Foundayo™ Medication Guide [2] |
| Rash with fever, joint pain or a sore throat | Your healthcare provider | Today | MedlinePlus [9] |
| Red streaks, swelling or very tender skin around a rash | Your healthcare provider, as these can mean infection | Today | MedlinePlus [9] |
| A new rash while taking a new medicine such as Foundayo™ | Your prescriber; do not stop or change medicines on your own | At your next appointment | MedlinePlus [9] |
| Hives that are severe or do not respond to self-care | Your healthcare provider | At your next appointment | MedlinePlus [10] |
