Medicines & Supplements A to Z > Doxycycline


Last updated on 22/03/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Doxycycline 


BRAND NAME(S) IN HONG KONG: Amermycin, Doxycap, Tolexine, Vibramycin 

DRUG CLASS: Tetracycline antibiotic 

USED FOR: Acne, pneumonia, peritonitis, syphilis, pelvic inflammatory disease, traveller’s diarrhea and other bacterial infections, prevention of malaria

OTHER DRUGS IN THE SAME CLASS: Minocycline, Oxytetracycline, Tetracycline

– 50mg, 100mg (tablets)
– 100mg (capsules)

What is Doxycycline for?

Doxycycline is an antibiotic for treating bacterial infections, including but not limited to the following:

– Community acquired pneumonia
– Syphilis
– Epididymo-orchitis
Chloroquine resistant falciparum malaria acute attack
– Relapsing fever and louse-borne typhus
– Nongonococcal urethritis
– Pelvic inflammatory disease
– Uncomplicated gonorrhoea
– Leptospirosis
– Traveller’s diarrhoea
– Prevention of malaria

How to use it?

For susceptible infections

Adult / Child (body weight ≥45 kg)
200 mg as a single dose OR in 2 divided doses every 12 hours on the first day, then 100 mg once daily; For severe infections: 200 mg daily.
Child (body weight <45 kg)
4.4 mg/kg in 2 divided doses on the first day then 2.2 mg/kg; For severe infections: 2.2 mg/kg 12 every 1 hour.

For syphilis

Adult: 300 mg daily in divided doses for at least 10 days.

For epididymo-orchitis (Infection caused by Chlamydia trachomatis or Neisseria gonorrhoeae) 

Adult: 100 mg twice daily for at least 10 days. 

For nongonococcal urethritis / sexually transmitted diseases / uncomplicated gonorrhoea

Adult: 100 mg twice daily for 7 days.

For prevention of traveller’s diarrhoea

Adult: 200 mg as a single dose OR in 2 divided doses on the first day of travel, then 100 mg once daily throughout your trip.

For prevention of malaria

Orally using dispersible tablets
Adult / Child (body weight ≥45 kg)
100 mg daily starting 1-2 days before travelling to malarial areas, continue to take it daily during your trip and for 4 weeks after leaving the malarial areas.
Child ≥ 12 years (body weight <45 kg)
2.2 mg/kg once daily.

What are the side effects of Doxycycline?

Common side effects of Doxycycline include, diarrhoea, headache, allergic skin reactions, nausea and vomiting, pericarditis, sensitivity to sun.

Who should not take Doxycycline?

– People who are allergic to Doxycycline, other tetracycline antibiotics, or any formulation component
– Infants and children younger than 8 years old
– Women on second or third-trimester pregnancy
– Breastfeeding women

Pharmacist Tips:

– Your skin may become sensitive to sunlight after taking Doxycycline. Avoid prolonged exposure to sunlight and ultraviolet light. Apply sunscreen as needed.
Take magnesium, calcium or iron-containing products, such as antacids, at least 2 hours before or 4 hours after taking Doxycycline.

Common dosing schedule:
Take Doxycycline with or after meal to reduce stomach upset. However, avoid meals rich in fat or milk.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Doxycycline may interact with:
– Antacids
– Calcium
– Retinoic acid derivatives, e.g. Isotretinoin

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Doxycycline in Hong Kong?

In Hong Kong, Doxycycline is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Doxycycline in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.