Tirzepatide 'injection site' hacks: what TikTok gets wrong

What did @ashtclaire actually say?

She injected tirzepatide into her flank (love handle area), offered two specific injection tips, and described being on a 12.5 mg dose requiring two separate injections because her syringe only holds 100 units. She said "do not inject directly into a stretch mark" and warned against squeezing the skin on your side the way you might on your abdomen. She framed herself as a guinea pig sharing real-time experience, not giving medical advice, and made that explicit: "I didn't tell you to do anything."

That disclaimer matters. But 108,000 views means a lot of people are watching someone self-inject and narrating their technique in real time, regardless of intent. So let's check what she actually said against what the evidence supports.

Does the science back this up?

Partially, yes. The flank is a legitimate injection site for subcutaneous GLP-1 medications, and the stretch mark caution has some practical basis, though the clinical literature is thinner than you'd hope.

Tirzepatide (Zepbound/Mounjaro) is approved for subcutaneous injection into the abdomen, thigh, or upper arm. The flank is not listed as a primary site in Eli Lilly's prescribing information, but it's anatomically similar to the abdomen in terms of subcutaneous fat depth in many patients. A 2022 review in Diabetes Technology and Therapeutics (Spollett et al.) noted that injection site selection should prioritize areas with adequate subcutaneous fat and consistent absorption characteristics. Flanks can meet that criteria, especially in patients with higher body fat distribution, but rotation across approved sites is the standard recommendation.

Her point about squeezing the flank skin being uncomfortable has no direct clinical citation behind it, but it's consistent with the general guidance that pinching technique should adapt to site anatomy. Skin tension on the flank is different from the abdomen.

What did they get wrong (or right)?

She got more right than wrong, but one gap stands out: she did not mention injection site rotation, which is not optional.

Injecting repeatedly into the same site causes lipohypertrophy, a buildup of fatty tissue that impairs drug absorption. This is well-documented with insulin (Blanco et al., 2013, Diabetes Care) and is presumed to apply to GLP-1 subcutaneous injections by the same mechanism. The flank can be a site, but it should be part of a rotation, not a destination.

Her stretch mark warning is practically reasonable. Stretch marks represent disrupted dermal and subdermal architecture, scar-like tissue that can make injection more uncomfortable and may affect absorption, though direct evidence specific to GLP-1 injections is sparse. She's not wrong to flag it.

What she got right: the 12.5 mg dose split across two injections is a real logistical issue some patients face depending on their supplies, and acknowledging it openly is more useful than pretending it doesn't happen. She also correctly avoids claiming any clinical outcome from the injection method.

What should you actually know?

Your prescribing clinician and pharmacist are the right sources for injection site guidance, not a TikTok, including this one. That said, here is what the actual evidence says.

• Approved subcutaneous sites for tirzepatide per Lilly's prescribing information are the abdomen (avoid 2-inch radius around navel), upper arm, and thigh. The flank is not listed.
• Injection site rotation matters clinically. Lipohypertrophy can reduce drug bioavailability by up to 25% (Johansson et al., 2005, Diabetic Medicine), which at these medication price points is both a health and financial issue.
• Pinching technique varies by site. The abdomen often benefits from a pinch-lift; the flank has different tissue tension and less consensus guidance.
• Splitting a dose across two injections because of syringe capacity is a practical reality for some compounded tirzepatide users. If you are doing this, confirm the approach with whoever prescribed it, since timing and technique matter for subcutaneous absorption.
• Do not inject into areas of active inflammation, bruising, or scarring, including stretch marks if they are raised or indurated. This is standard subcutaneous injection guidance.

Bottom line

@ashtclaire is sharing personal experience, not a clinical tutorial, and she says so. Her specific tips are not dangerous and some are practically sensible. But a video this popular that shows injection technique without mentioning site rotation is leaving out something that actually affects how well your medication works. That omission is worth noting even if it was never her intent to give complete clinical guidance.