Intramuscular vs Subcutaneous injections what's the difference? At KDR, we often use peptides and wellness injections like NAD, glutathione, and HCG, but they are not all administered the same way. Intramuscular injections ( How Much is Too Much? Mastering Your Glutathione Injection Dosage Per Week Is subcutaneous (sub q) glutathione injection safe and effective as a supplement for asthma management? Subcutaneous injection: Definition and what to expect