Niacinamide and Semaglutide Together: Complete Guide

Niacinamide, also known as nicotinamide, is the amide form of vitamin B3. It is water-soluble, serves as a precursor to NAD+ and NADP+ (cofactors in energy metabolism and DNA repair), and is available over the counter.

Niacinamide is NOT the same as niacin (nicotinic acid). Both are forms of vitamin B3 but behave differently:

• Niacin (nicotinic acid) causes the classic "niacin flush" at doses above 30-50 mg because it releases histamine and activates GPR109A. Used clinically at high doses for dyslipidemia.
• Niacinamide (nicotinamide) does NOT cause flushing, does NOT meaningfully affect blood lipids, and is used in dermatology and general B3 supplementation.

When a compounded semaglutide product says "niacinamide" or "nicotinamide," it is the flush-free form. Every compounding pharmacy formulation uses this form.

Supplemental dose context: - RDA: 14-16 mg daily - Typical OTC supplement: 100-500 mg daily - Dose in compounded semaglutide: 10-30 mg per mL, meaning a weekly 0.25 mL injection delivers 2.5-7.5 mg

The amount of niacinamide you receive from a weekly compounded semaglutide injection is small. It will not meaningfully affect your vitamin B3 status, which is part of why its clinical benefit in these formulations is questionable.

There are three stated rationales. They have different levels of evidence.

Rationale 1: Peptide stability in solution.

Semaglutide is a 31-amino-acid peptide susceptible to degradation through oxidation, aggregation, deamidation, and hydrolysis. Niacinamide has been studied as a stabilizing agent in pharmaceutical literature through proposed mechanisms like mild antioxidant activity, reduced aggregation via hydrogen bonding, and pH buffering. The evidence here is in-vitro and formulation-science based. No published human studies show niacinamide-containing semaglutide produces better clinical outcomes than pure semaglutide.

Rationale 2: Anti-inflammatory adjunct.

Niacinamide has documented anti-inflammatory effects in dermatology and modest systemic effects at higher oral doses, acting through inhibition of NF-kB signaling and modulation of PARP-1 and SIRT1 activity (Niren, 2006). Some compounding pharmacies extrapolate this: rapid weight loss produces transient metabolic inflammation, and niacinamide might buffer it. The extrapolation is weak. The dose in a weekly injection (a few milligrams) is far below the doses (500-1500 mg daily orally) that show measurable anti-inflammatory effects. This rationale is largely marketing.

Rationale 3: Vitamin supplementation during weight loss.

Semaglutide reduces food intake substantially, and patients eating 1000-1500 kcal daily may become deficient in B vitamins. Adding a B vitamin is pitched as "insurance." This rationale is more valid for B12 than niacinamide. GLP-1 therapy may reduce B12 absorption through slower gastric emptying and altered stomach acid. Niacinamide deficiency from semaglutide-induced food restriction is extremely uncommon because B3 is abundant in protein foods and is not affected by GLP-1 absorption mechanisms.

The honest summary: Most compounding pharmacies add niacinamide for a mix of theoretical stability benefits and marketing differentiation. It is not harmful but also not a proven clinical benefit. For vitamin support, oral multivitamins or targeted B12 are better approaches than relying on a few milligrams of niacinamide in a weekly injection. For the more evidence-supported variant, see compound semaglutide with B12.

The most common compounded semaglutide additive is cyanocobalamin (vitamin B12), not niacinamide. Understanding the difference helps you evaluate the formulation you are being offered.

Semaglutide + B12: - B12 concentration in compounded product: typically 1000 mcg per mL - Clinical rationale: GLP-1 therapy reduces gastric acid and slows gastric emptying, which impairs dietary B12 absorption. Longer-term users of semaglutide have measurably lower B12 levels. The B12 deficiency mechanism is well established with metformin (also used for type 2 diabetes), where calcium-dependent intrinsic factor binding is disrupted (Bauman et al., 2000). - Evidence strength: moderate. B12 deficiency during GLP-1 therapy is documented. Whether injected B12 at these doses prevents deficiency is mechanistically plausible. - Safety: B12 has no meaningful toxicity. Excess is excreted renally. - Side effect profile: generally well tolerated. Some patients notice a pink tinge to the solution (cyanocobalamin is pink/red).

Semaglutide + niacinamide: - Niacinamide concentration: typically 10-30 mg per mL - Clinical rationale: stability, anti-inflammatory effect, vitamin B3 support - Evidence strength: low for clinical benefit. Some formulation-science data for stability. - Safety: generally safe at these doses. Not niacin, no flushing. - Side effect profile: generally unnoticeable at the low delivered dose.

Semaglutide + both (less common): - Some pharmacies combine both additives - The rationale is cumulative: stability + B12 absorption support + B3 backup - No added clinical evidence beyond the individual components

Pure semaglutide (no additives): - Gold standard for predictability - What brand Wegovy and Ozempic contain (along with their own excipients) - Easiest to compare across studies and dose titration

Which should you prefer?

If you are choosing between compounded formulations: 1. Plain semaglutide if you want the cleanest comparison to brand product outcomes. 2. Semaglutide + B12 if you have documented or suspected B12 deficiency risk, or if you plan to stay on semaglutide for more than 6 months. 3. Semaglutide + niacinamide only if your pharmacy exclusively offers this formulation and the other options are not available. 4. Semaglutide + both if your provider believes you need the combined vitamin support, with the caveat that this is additive risk of allergic reactions to any single component.

For the tirzepatide equivalent of this decision, see compound tirzepatide dosage chart and is compound tirzepatide safe.

At the doses present in compounded semaglutide (a few milligrams per weekly injection), niacinamide has a very favorable safety profile. Most people will not experience any niacinamide-attributable effect.

Niacinamide-specific concerns:

• Liver enzymes: very high oral doses (above 3 grams daily) have been associated with elevated liver enzymes. Injected amounts in compounded semaglutide are approximately 1/100th of that dose, so not a practical concern. Patients with pre-existing liver disease should inform their provider.
• Thrombocytopenia: rare reports at high doses. Compounded dose is far below the range of concern; patients with hematological conditions should discuss with their provider.
• Pregnancy and lactation: niacinamide at supplemental doses is safe. However, semaglutide itself is NOT recommended in pregnancy, so the combined product is contraindicated regardless of the vitamin.
• Drug interactions: carbamazepine and primidone may be slightly affected; at the doses in compounded semaglutide, interactions are not clinically significant.

Semaglutide-specific safety (applies to all formulations): The semaglutide component drives the major side effect profile: - GI: nausea, vomiting, constipation, diarrhea (common) - Gallbladder: risk of gallstones during rapid weight loss - Pancreatitis: rare but serious; discontinue and evaluate if severe abdominal pain - Thyroid C-cell tumors: contraindicated in personal/family history of MTC or MEN2 - Hypoglycemia: primarily with concurrent insulin or sulfonylurea use - Retinopathy: rapid A1c reduction can transiently worsen diabetic retinopathy

For the full side effect profile, see does semaglutide cause nausea and does semaglutide cause hair loss.

Storage: refrigerate at 2-8 degrees Celsius, protect from light, do not freeze, discard if cloudy or particulate. Niacinamide does not change handling requirements.

Warning signs to stop and contact your provider: severe abdominal pain, persistent vomiting, rash or breathing difficulty after injection, visual changes, unusual fatigue or jaundice.

For titration safety, see semaglutide titration schedule. For expected timelines, see how long does semaglutide take to work.

Every compounded injection should have a clear label. If yours does not, contact the compounding pharmacy before using.

Required label elements:

1. 1.Drug name ("Semaglutide" or "Semaglutide with niacinamide")
2. 2.Semaglutide concentration in mg/mL (commonly 2.5 mg/mL or 5 mg/mL)
3. 3.Niacinamide concentration in mg/mL (commonly 10-30 mg/mL)
4. 4.Total volume in mL (commonly 2-5 mL)
5. 5.Lot number and expiration/beyond-use date
6. 6.Compounding pharmacy name and license
7. 7.Storage instructions ("Refrigerate 2-8°C, protect from light")
8. 8.Prescription fill number

Calculating your dose: If your label reads "Semaglutide 5 mg/mL with niacinamide 20 mg/mL" and your prescription is 0.5 mg semaglutide weekly: - Semaglutide: 0.5 mg / 5 mg per mL = 0.1 mL injection volume - Niacinamide delivered: 20 mg/mL × 0.1 mL = 2 mg per week (less than a fifth of a supplement tablet)

Use the semaglutide dosage calculator for a step-by-step calculation.

Labeling red flags:

• Vague "peptide blend" or "proprietary GLP-1 complex": a legitimate compounded product names every active ingredient with its exact concentration.
• Missing pharmacy name: every compounded product should trace to a named licensed pharmacy.
• No beyond-use date: compounded semaglutide has a finite stability window (commonly 28-56 days refrigerated).
• Inconsistent concentrations across refills: concentration changes without a new prescription mean your mL dose will change and you could under- or overdose.

Most compounded semaglutide arrives pre-reconstituted. Some ships as lyophilized powder requiring bacteriostatic water reconstitution. See semaglutide mixing chart for reconstitution math. For the parallel sourcing framework, see where to buy tirzepatide.