Ascorbic Acid
L-ascorbic acid
Also known as: Vitamin C · Ascor L 500 · L-ascorbic acid · Antiscorbutic vitamin · Ascorbate
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Dosing by species
Dosing data for this drug is not yet available in the VetSheet formulary. Every other section below is complete. Consult the current product label before prescribing.
Overview
Ascorbic acid (Vitamin C) is a water-soluble vitamin essential for collagen synthesis, tissue repair, and antioxidant defense.
While most domestic animals (such as dogs, cats, and horses) synthesize adequate amounts of Vitamin C endogenously in their liver, certain species—most notably guinea pigs, non-human primates, and some bats and birds—lack the enzyme L-gulonolactone oxidase and require dietary supplementation.
In veterinary medicine, ascorbic acid is primarily used to:
- Treat and prevent scurvy in susceptible species (e.g., guinea pigs).
- Serve as an adjunctive antioxidant therapy in critical care or hemolytic events.
- Act as a urinary acidifier.
- Assist in the management of specific toxicities, such as red maple leaf toxicosis in horses or acetaminophen toxicity, due to its methemoglobin-reducing properties.
Mechanism of action
Ascorbic acid acts as a vital coenzyme and a powerful water-soluble antioxidant.
- Collagen Synthesis: It is an essential cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase → facilitates the hydroxylation of proline and lysine residues → allows for the formation of a stable collagen triple helix.
- Antioxidant Activity: Scavenges reactive oxygen species (ROS) → protects lipid membranes, DNA, and proteins from oxidative damage.
- Methemoglobin Reduction: Assists in the reduction of methemoglobin back to functional hemoglobin, which is beneficial in certain oxidative toxicities.
- Iron Absorption: Enhances the gastrointestinal absorption of non-heme iron and regulates iron transport.
Safety & warnings
Contraindications
- Patients with a history of urate or calcium oxalate urolithiasis
- Use with caution in patients with iron storage diseases (e.g., hemochromatosis)
- Patients with a history of calcium oxalate or urate urolithiasis (due to urine acidification)
Adverse effects
- Gastrointestinal upset (diarrhea) with high oral doses
- Pain or tissue irritation at the injection site (IM or SC)
- Increased risk of calcium oxalate urolithiasis with chronic high-dose administration
- Gastrointestinal upset (diarrhea) at high oral doses
- Pain at injection site (IM/SC)
- Potential to acidify urine, which may increase the risk of oxalate or urate urolithiasis
Precautions
Use with extreme caution in animals prone to calcium oxalate urolithiasis, as ascorbic acid is partially metabolized to oxalate and excreted in the urine. Intravenous administration should be performed slowly to avoid adverse cardiovascular events. Injectable solutions should be protected from light.
Drug interactions
Concurrent use may exacerbate tissue iron toxicity, particularly in the heart.
May have additive acidifying effects, potentially increasing the risk of crystalluria.
Monitoring
- Clinical signs of disease resolution (e.g., improvement of scurvy symptoms in guinea pigs)
- Urine pH (if utilized specifically as a urinary acidifier)
- Resolution of clinical signs of scurvy (in susceptible species)
- Urine pH (if using high doses)
Pharmacokinetics
Half-life
Absorption
Readily absorbed from the gastrointestinal tract (primarily the jejunum) via active transport mechanisms.
Distribution
Widely distributed to all body tissues; particularly high concentrations are found in glandular tissue, leukocytes, the liver, and the lens of the eye.
Metabolism
Reversibly oxidized to dehydroascorbic acid; partially metabolized in the liver to inactive compounds, including oxalic acid.
Elimination
Excreted primarily in the urine. A renal threshold exists; once tissue saturation is reached, excess ascorbic acid is excreted unchanged in the urine.
Overdose
Ascorbic acid is generally very safe due to its water-soluble nature; excess amounts are rapidly excreted in the urine. Massive acute overdoses may cause gastrointestinal disturbances (such as diarrhea) or mild acidosis. Chronic overdosage significantly increases the risk of calcium oxalate urolithiasis.
Available products
Formulations
- Injection: 500 mg/mL in 50 mL vials (0.025% EDTA, preservative-free)
- Injectable: 100 mg/ml
- Oral: various strength tablets, capsules, powders and liquids
Veterinary
- Ascor L 500® (McGuff): 500 mg/mL injection in 50 mL vials
- Various injectable solutions (100 mg/ml) (POM)
- Various oral supplements (General Sale)
Human-labeled
- Various over-the-counter oral tablets, capsules, chewables, and liquids
- Generic injectable formulations
- Various tablets, capsules, chewables, powders, and liquids
Regulatory status
Injectable forms are typically POM (Prescription Only Medicine), while oral forms are General Sale.
Injectable forms are POM-V; oral forms are General Sale List (GSL).
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store intact vials at controlled room temperature and protect from light. Preservative-free solutions should be used promptly after opening, and any unused portion should be discarded.
Client information
Key Point: Most dogs and cats naturally produce their own Vitamin C and do not require supplements unless specifically directed by your veterinarian.
- Guinea pigs cannot make their own Vitamin C and must receive daily supplementation through a fortified diet or specific Vitamin C drops.
- Store Vitamin C supplements in a cool, dark place, as the vitamin degrades quickly when exposed to light and air.
- If your pet is prescribed high doses, monitor their stool; contact your veterinarian if diarrhea occurs.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.