II. Indications
- Skin disorders
 - Gastrointestinal disorders
- Helicobacter Pylori (part of quadruple therapy protocol)
 
 - Tick Borne Illness
 - Miscellaneous disorders
 - Sexually Transmitted Disease
 
III. Contraindications
- Pregnancy
 
IV. Mechanism
- See Tetracyclines
 
V. Precautions
- AAP now approves Doxycycline for ANY age up to 21 day duration (esp. Tick Borne Illness)
 
VI. Medications
- Capsule (Doxycycline Monohydrate)
- Strengths: 50,75,100,150 mg (generics available)
 
 - Tablet (Doxycycline Monohydrate)
- Strengths: 50,75,100,150 mg (generics available)
 
 - Tablet (Doxycycline Hyclate)
- Strengths: 20,50,75,100,150 mg (generics available)
 
 - Doxycyline Hyclate Delayed-Release (Doryx MPC)
- Expensive ($10/pill) formulated to by-pass the Esophagus for less side effects
 - Alternatively, take the doxycyline with 8 oz water and food
 - (2016) Presc Lett 23(11)
 
 
VII. Dosing: Adults (weight >45 kg)
- Typical dose: 100 mg orally twice daily
 - Low doses, such as 50 mg daily, are often as effective for Acne Vulgaris
 - Avoid substituting low-dose Doxycycline (Periostat, Oracea) products for systemic infections
 - May substitute other Doxycycline salts
- Doxycycline hyclate (Vibramycin, Doryx)
 - Doxycycline monohydrate (Monodox)
 - (2013) Presc Lett 20(5):26
 
 
VIII. Adverse Effects
- Photosensitivity
- Use sun protection (e.g. Sunscreen)
 
 - 
                          Pill Esophagitis
                          
- Take with 8 ounces fluid
 
 - 
                          Drug-Induced Tooth Staining
                          
- Compared with Tetracycline, Doxcycyline is unlikely to cause tooth staining in children, even under age 8 years.
 - Frequency: Uncommon to rare
 
 - Abdominal Pain
 - Diarrhea
 - 
                          Pseudotumor Cerebri
                          
- Rare Tetracycline class effect
 
 
IX. Safety
- Pregnancy Category D (all trimesters)
 - Unknown safety in Lactation
 
X. Drug Interactions
- Doxycycline Decreases Absorption Of Other Substances
 - Doxycycline Level Decreased By Other Substance
 - Food Related
- Doxycycline can be taken with milk or food (unlike Tetracycline)
 - Take with a full glass of water (risk of Pill Esophagitis)
 
 - 
                          Warfarin
                          
- Increases INR
 
 
XI. Pharmacokinetics
- Absorption: Not affected by food or milk intake (unlike Tetracycline)
 - Peak Activity: >2.6 hours
 - Half Life: 18-22 hours
 - Primary Elimination: Renal (>40%)
 - Other Elimination: Hepatic
 
XII. Resources
- DailyMed (accessed 10/3/2021)
 - DailyMed (accessed 10/3/2021)
 
Images: Related links to external sites (from Bing)
Related Studies
| doxycycline (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| DOXYCYCLINE 25 MG/5 ML SUSP | Generic | $0.23 per ml | 
| DOXYCYCLINE 50 MG TABLET | Generic | $4.97 each | 
| DOXYCYCLINE HYC DR 150 MG TAB | Generic | $2.77 each | 
| DOXYCYCLINE HYCLATE 100 MG CAP | Generic | $0.14 each | 
| DOXYCYCLINE HYCLATE 100 MG TAB | Generic | $0.12 each | 
| DOXYCYCLINE HYCLATE 20 MG TAB | Generic | $0.14 each | 
| DOXYCYCLINE HYCLATE 50 MG CAP | Generic | $0.20 each | 
| DOXYCYCLINE IR-DR 40 MG CAP | Generic | $14.32 each | 
| DOXYCYCLINE MONO 100 MG CAP | Generic | $0.24 each | 
| DOXYCYCLINE MONO 100 MG TABLET | Generic | $0.31 each | 
| DOXYCYCLINE MONO 50 MG CAP | Generic | $0.17 each | 
| DOXYCYCLINE MONO 50 MG TABLET | Generic | $0.21 each |