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Doxycycline is primarily used to treat bacterial infections, including pneumonia, acne, urinary tract infections, and certain sexually transmitted infections (STIs).

Last Modified: 17 May 2024

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What is Doxycycline? 

Doxycycline is a broad-spectrum antibiotic that belongs to the tetracycline class of antibiotics. It's known for fighting a wide range of bacterial infections. 

Global Name

Generic name: Doxycycline 
Brand names: Vibramycin, Oracea, Doryx


What is Doxycycline used for? 

Doxycycline is primarily used to treat bacterial infections, including pneumonia, acne, urinary tract infections, and certain sexually transmitted infections (STIs). It's also used  as malaria prophylaxis (prevention of malaria for travels to endemic places), treatment of tick-borne diseases such as scrub typhus caused by Rickettsiae bacteria (common in hiking) and treat anthrax exposure. 

How do you use Doxycycline? 


Doxycycline is available in tablets, capsules, and liquid forms.

Dosage information: 

  • Adults: 100 mg every 12 hours for the first day, then 100 mg daily; doses may vary based on the infection. 
  • Children: Over 8 years old, 2.2 mg/kg body weight given once daily. 


  • Children: Not recommended under 8 due to risks of tooth discoloration and bone growth impact. Exceptions may apply for severe infections with careful dosing. 
  • Adults: Generally safe when prescribed. Adherence to dosage and treatment duration is crucial. 
  • Elderlies: May need dosage adjustments; monitor kidney function and for other age-related issues. 
  • Pregnancy: Not advised due to potential fetal harm. Please consult with your healthcare provider.  
  • Lactation: Use with caution. Doxycycline passes into breast milk, and alternatives should be considered to avoid affecting the infant's bone and teeth development. Please consult with your healthcare provider.


  • Allergies: To doxycycline or other tetracyclines. 

  • Medical Conditions: Severe liver disease, or if you are taking isotretinoin or acitretin. 


Doxycycline can make you more prone to sunburn. Use sunscreen and wear protective clothing when outdoors.


Avoid taking with dairy products, antacids, or iron supplements, as these can decrease absorption. 

Side Effects

Common side effects include nausea, diarrhea, and sensitivity to sunlight. 

Pharmacist Tips

  • Storage: Keep doxycycline away from light and moisture at room temperature. 
  • Administration: Take with a full glass of water and remain upright for at least 30 minutes afterward. 
  • Sun Safety: Use sunscreen and wear protective clothing outdoors to prevent sunburn. 
  • Missed Doses: Take missed doses as soon as possible unless it's near the next scheduled dose. 
  • Diet: Avoid dairy with doxycycline and space out antacids or iron supplements by two hours. 
  • Course Completion: Finish the prescribed course to fully eradicate the infection and prevent resistance. 
  • Side Effects: Monitor for nausea or diarrhea. Probiotics may help but consult your doctor first. 
  • Medical History: Inform your doctor of any liver or kidney issues before starting treatment. 


Where is Doxycycline available in Hong Kong?

Doxycycline is a prescription medication that can be prescribed by healthcare providers.


Where can I buy Doxycycline?  

Doxycycline requires a prescription from a healthcare provider.

Can Doxycycline treat viral infections like the flu?

No, it is not effective against viral infections.

Should I take Doxycycline with food?

It's best taken on an empty stomach, but if stomach upset occurs, take it after food or a glass of milk. 

This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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