NutriStack
Amphetamine/Dextroamphetamine and Vitamin C, timing-sensitive.
High-dose Vitamin C products are usually ascorbic acid, and acidifying conditions can lower amphetamine blood levels by increasing renal clearance of amphetamine. This can make amphetamine/dextroamphetamine feel weaker or wear off sooner in some patients, though ordinary dietary vitamin C is less likely to cause a major effect. The risk is most relevant with large supplemental doses, acidic powders, or inconsistent timing.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
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What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Amphetamine/Dextroamphetamine and Vitamin C
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Moderate
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Timing Sensitive · Moderate evidence
Timing Sensitive
What is happening. High-dose Vitamin C products are usually ascorbic acid, and acidifying conditions can lower amphetamine blood levels by increasing renal clearance of amphetamine. This can make amphetamine/dextroamphetamine feel weaker or wear off sooner in some patients, though ordinary dietary vitamin C is less likely to cause a major effect. The risk is most relevant with large supplemental doses, acidic powders, or inconsistent timing.
Mechanism. Amphetamine is a weak base with renal elimination that is sensitive to urinary pH; lower urinary pH increases ionization and renal excretion, reducing systemic exposure. Ascorbic acid products can contribute to acidifying conditions, while routine food-level vitamin C is less predictable and usually lower risk.
Recommendation. Keep Vitamin C intake consistent and avoid taking high-dose Vitamin C within 2 hours of amphetamine/dextroamphetamine. If you use gram-level Vitamin C daily, take it later in the day and tell your prescriber if your stimulant effect changes. Do not increase stimulant doses on your own to compensate.
Minimum separation. 120
Sources (3)
- Wan SH, Matin SB, Azarnoff DL. Kinetics, salivary excretion of amphetamine isomers, and effect of urinary pH. Clin Pharmacol Ther. 1978;23(5):585-590. PMID 25157
- Huang W, Czuba LC, Isoherranen N. Mechanistic PBPK Modeling of Urine pH Effect on Renal and Systemic Disposition of Methamphetamine and Amphetamine. J Pharmacol Exp Ther. 2020;373(3):488-501. PMID 32198137
- Hetey SK, Kleinberg ML, Parker WD, Johnson EW. Effect of ascorbic acid on urine pH in patients with injured spinal cords. Am J Hosp Pharm. 1980;37(2):235-237. PMID 7361797
Stack Score
How this pair moves the number.
Effect on the composite score
If both Amphetamine/Dextroamphetamine and Vitamin C are in the same stack, this pair applies −5 to your Stack Score (per scored timing-sensitive row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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