Minocycline
Minocycline Hydrochloride
Also known as: Minocin · Dynacin · Solodyn · Myrac · Arestin · Aknemin · minocyclini hydrochloridum · Asolmicina · Cyclimycin · Cyclomin · Dermirex · Meibi · Minogal · Minox · Minocyclinum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidenceLyme borreliosis (extra-label)
Verified clinician required
- q12-24h
NA
Governing clinical context (6)
- NOTE: No clinical studies using IV minocycline were located.
- Considering minocycline’s bioavailability, use of IV dosages at the lower end of the oral range appears to be reasonable. Doses administered IV should be given over at least 10 minutes. 33,34 Immediate-release formulations are used for oral dosages.
- Considering minocycline’s bioavailability, use of IV dosages at the lower end of the oral range appears to be reasonable. Doses administered IV should be given over at least 10 minutes. 33,34 Immediate-release formulations are used for oral dosages.
- Store oral preparations at room temperature in tight containers. Do not freeze oral suspensions. The injectable should be stored at room temperature ( 20°C-25°C [68°F-77°F]) and protected from light, moisture, and excessive heat. After reconstitution with sterile water for injection, solutions with a concentration of 20 mg/mL are stable for 4 hours at room temperature or for 24 hours if refrigerated.
- ■ Oral minocycline works best when given without food. If your animal vomits or acts sick after receiving the medicine on an empty stomach, try giving the next dose with a small amount of food or a treat.
- ■ Do not give antacids, including sucralfate, oral iron, and antidiarrheal medicine, within 2 hours before or after giving minocycline.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Minocycline is a highly lipophilic, second-generation tetracycline antibiotic. It is notable for its excellent tissue penetration, including crossing the blood-brain barrier and entering the prostate.
- Clinical Uses: Brucellosis, Lyme disease, hemotropic mycoplasmosis, atypical mycobacterial infections, and resistant nosocomial infections.
- Advantages: Less likely to cause bone and teeth abnormalities compared to older, more water-soluble tetracyclines. It can be safely used in patients with moderate renal insufficiency without dosage adjustment.
- Additional Properties: Beyond antimicrobial effects, minocycline exhibits anti-inflammatory and neuroprotective properties (e.g., inhibition of matrix metalloproteinases), which has led to its investigation as an adjunctive therapy for conditions like hemangiosarcoma, though early results have been disappointing.
Mechanism of action
Minocycline is a bacteriostatic antibiotic that exhibits time-dependent (AUC/MIC) inhibition of bacterial growth.
- Primary Mechanism: Reversibly binds to the 30S ribosomal subunit of susceptible organisms → blocks the binding of aminoacyl transfer-RNA to the mRNA-ribosome complex → inhibits bacterial protein synthesis.
- Secondary Mechanism: Reversibly binds to the 50S ribosomal subunit → alters cytoplasmic membrane permeability, leading to leakage of intracellular components.
- Mammalian Effects: At very high concentrations, it can inhibit mammalian protein synthesis. It also inhibits matrix metalloproteinases (MMPs) and apoptosis, contributing to its anti-inflammatory and neuroprotective effects.
Safety & warnings
Contraindications
- Hypersensitivity to tetracyclines
- Pregnant or nursing animals
- Animals less than 6 months old (relative contraindication)
- Pregnancy
- Young, developing animals
Adverse effects
- Nausea and vomiting (most common)
- Dental or bone staining (if exposed in utero or early life)
- Increases in hepatic enzymes (rare)
- Ototoxicity (rare)
- Urticaria, shivering, hypotension, dyspnea, cardiac arrhythmias, and shock (if given rapidly IV)
- Superinfections (overgrowth of non-susceptible bacteria or fungi)
- Photosensitivity (reported in humans)
- Hepatotoxicity or blood dyscrasias (rare, reported in humans)
- CNS effects like dizziness/lightheadedness (reported in humans)
- Blue-gray pigmentation of skin and mucous membranes (reported in humans)
- Diarrhoea
- Bone and teeth abnormalities (in developing animals)
- Oesophageal erosions (especially in cats if dry-pilled)
Precautions
Intravenous Administration: Give IV injections slowly. Rapid IV injection in dogs has caused urticaria, shivering, hypotension, dyspnea, arrhythmias, and shock.
- Renal Impairment: Can be used in moderate renal insufficiency without dosage adjustment, but oliguric renal failure may require adjustment.
- Pregnancy/Nursing: Avoid use during pregnancy unless benefits outweigh fetal risks (can retard fetal skeletal development and discolor deciduous teeth). Avoid during nursing as it is excreted in milk.
- Laboratory Interference: Can cause false-positive urine glucose results (cupric sulfate method) or false-negative results (glucose oxidase method).
Drug interactions
Can chelate divalent or trivalent cations, decreasing absorption of the tetracycline. Give at least 12 hours before or after the cation-containing product.
May reduce minocycline absorption.
Decreased tetracycline absorption. Give iron salts 3 hours before or 2 hours after the tetracycline dose.
May increase the risk for nervous system effects when used concurrently.
Bacteriostatic drugs may interfere with the bactericidal activity of these antibiotics (clinical significance is controversial).
Tetracyclines may depress plasma prothrombin activity; anticoagulant dosage adjustment may be needed.
Reduced absorption of minocycline
Reduced absorption of minocycline
Reduced absorption of minocycline
Reduced absorption of minocycline
Reduced absorption of minocycline
Increased metabolism of minocycline, decreasing plasma levels
Increased metabolism of minocycline, decreasing plasma levels
Monitoring
- Clinical efficacy (resolution of infection)
- Adverse effects (GI upset, signs of hypersensitivity)
- Renal function (if used concurrently with nephrotoxic drugs like gentamicin)
- Gastrointestinal signs
- Hepatic function (in patients with pre-existing liver disease)
Pharmacokinetics
Half-life
Absorption
Well absorbed after oral administration regardless of the presence of food.
Distribution
Highly lipid soluble and distributed widely throughout the body. Therapeutic levels can be found in the CSF (whether meninges are inflamed or not), prostate, saliva, and eye.
Metabolism
Extensively metabolized in the liver.
Elimination
Primarily excreted as inactive metabolites in the feces and urine. Less than 20% is excreted unchanged in the urine.
Overdose
Oral overdoses are most likely associated with GI disturbances (vomiting, anorexia, and/or diarrhea).
- Treatment: Although less vulnerable to chelation than other tetracyclines, oral administration of divalent or trivalent cation antacids may bind some of the drug and reduce GI distress.
- Supportive Care: Should the patient develop severe emesis or diarrhea, monitor fluids and electrolytes and replace if necessary.
Available products
Formulations
- Oral tablets
- Pellet-filled oral capsules
- Oral suspension
- Powder for injection
- Powdered microspheres (dental)
- 50 mg capsules
- 100 mg capsules
- 50 mg tablets
- 100 mg tablets
Human-labeled
- Minocycline HCl Oral Tablets: 50 mg, 75 mg & 100 mg
- Minocycline HCl Extended-Release Tablets: 45 mg, 65 mg, 90 mg, 115 mg & 135 mg (Dynacin, Myrac, Solodyn)
- Minocycline HCl Oral Capsules: 50 mg, 75 mg & 100 mg (Dynacin)
- Minocycline HCl Pellet-filled Oral Capsules: 50 mg & 100 mg (Minocin)
- Minocycline HCl Oral Suspension: 50 mg/5 mL (Minocin)
- Minocycline HCl Powder for Injection: 100 mg vials (Minocin)
- Minocycline HCl Powdered Microspheres, dental: 1 mg (Arestin)
- Aknemin 50 mg, 100 mg capsules/tablets
- Minocin 50 mg, 100 mg capsules/tablets
Regulatory status
POM (Prescription Only Medicine)
POM (Prescription Only Medicine)
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store oral preparations at room temperature in tight containers. Do not freeze the oral suspension. Store injectable at room temperature and protect from light. After reconstituting with sterile water for injection, 20 mg/mL solutions are stable for 24 hours at room temperature. Do not add calcium-containing IV fluids (like Ringer's) as precipitation could result.
Client information
Important: Give this medication exactly as prescribed for the entire duration recommended by your veterinarian, even if your pet appears completely well. Stopping early can lead to resistant infections.
- Administration: Can be given with or without food. If it causes stomach upset (nausea or vomiting), giving it with a small meal often helps alleviate these effects.
- Dairy Products: Unlike older tetracyclines, milk or other dairy products do not significantly alter the amount of minocycline absorbed.
- Side Effects: Watch for vomiting, diarrhea, or loss of appetite. Contact your veterinarian if these are severe or persistent.
- Storage: Keep oral medications at room temperature in a tightly closed container. Do not freeze the liquid suspension.
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.