Adverse events

• Common: nausea, diarrhea, vomiting, constipation, decreased appetite — mostly dose- and titration-dependent.

• Notable: gallbladder events; pancreatitis (rare); rodent thyroid C-cell tumor signal → boxed warning; contraindicated with personal/family history of medullary thyroid carcinoma or MEN2.

• Body composition: meaningful lean-mass loss accompanies fat loss — protein intake and resistance training matter.

• Off-label-specific: dosing errors from self-titration off multi-dose vials (see the reconstitution-math page).

Sourcing red flags — the molecule isn't the main risk; the supply is

• Mislabeling is documented in unapproved incretin supply — a vial labeled one drug may contain another, or an unverified dose.

• "99% purity" ≠ correct dose. Purity describes contaminants; potency is the amount of active drug. A pure vial can still be the wrong dose or the wrong compound.

• Safest supply is a Health-Canada-approved product dispensed by a licensed pharmacy on a prescription.

The flat-feeling signal (emerging — low evidence tier). A growing number of people report emotional blunting on GLP-1 drugs — reduced libido, feeling numb, loss of interest in relationships. The mechanism is plausible: GLP-1 receptor activity dampens dopamine signalling in the brain's reward circuitry, which is why it quiets "food noise" and alcohol craving — but that dampening doesn't necessarily stop at food. The evidence is patient reports, case reports, and mechanism — not randomized trials; no RCT has measured it with a validated instrument. The honest nuance: the same reward-dampening that helps someone with a dysregulated reward system can flatten someone whose reward system was healthy, and you often can't tell from the inside which is happening. If the people around you notice you've gone flat, take that as seriously as any physical side effect. → See the full discussion on Reward, motivation, and the flat feeling.