MOTS-c side effects and what's normal

MOTS-c makes your body burn more energy, and most of its common side effects follow directly from that.

Common and usually temporary

Feeling anxious or jittery, a bit like too much coffee. A direct consequence of a higher metabolic rate. It usually settles.
A faster heartbeat, or a fluttering feeling in your chest. Common on its own. Contact a provider if this feeling is associated with chest pain, lightheadedness, or lasts more than a few seconds at a time.
Redness or irritation where you inject. Rotating sites is the fix.
Disturbed sleep. This is usually a timing problem rather than a medication problem: a dose taken late in the day can keep you up. Move it to the morning.
Feeling tired instead of energized. A minority of people react this way and we do not fully understand why. It is not dangerous on its own, but it is worth telling us. It is a reason to reassess rather than to push through.

Low blood sugar (hypoglycemia). MOTS-c makes you more sensitive to insulin, so your blood sugar can drop too low. More likely if you also take a GLP-1, or if you skip a meal or train hard. The signs and the rule of 15 are in "How do I store, handle, and inject MOTS-c?" Read that before your first injection.
A serious allergic reaction. Any peptide can cause one, and this has happened rarely with MOTS-c.

You have had a low blood sugar episode. One is worth reporting; if it happens more than once, your plan needs adjusting and we want to know
You have chest pain, fainting, or a racing heart that does not settle (that is different from the common fluttering feeling and is a provider call)
MOTS-c is making you tired rather than energized - after at least 2 weeks of consistent treatment, weeks 1-2 should be told to continue and report back at weeks 3-4 to see if it improved
A side effect is severe, persistent, or getting worse instead of better
You notice signs of an allergic reaction such as a rash, hives, or swelling. For trouble breathing or swelling of the face, lips or tongue, seek emergency care first, then let us know