Doxycycline 100 mg tablets are a tetracycline antibiotic used for many infections and some travel/malaria-prevention uses. Dosing depends on the infection and your situation, so there isn’t a single “one-size-fits-all” dose. Here are some common patterns for adults (nonpregnant):
- Uncomplicated skin/soft tissue infections, bronchitis, sinusitis, community-acquired pneumonia (outpatient): 100 mg taken twice daily (every 12 hours). Typical total duration: 5–14 days, depending on the infection.
- Chlamydia (an STI): 100 mg twice daily for 7 days (often given with other medications per local guidelines).
- Tick-borne infections (e.g., Lyme disease, RMSF): 100 mg twice daily for about 10–21 days, depending on the specific illness.
- Malaria prophylaxis for travelers: 100 mg once daily, starting 1–2 days before travel, continuing during travel, and for 4 weeks after leaving the endemic area.
- Lyme disease after a tick bite (prophylaxis in some cases): a single 200 mg dose.
Important safety and dosing tips:
- Do not take if you are pregnant or breastfeeding, or if you are a child under about 8 years old, due to effects on teeth and bone development.
- Take with a full glass of water. Do not lie down for at least 30 minutes after taking to avoid throat/esophagus irritation.
- You can take doxycycline with food if it helps your stomach, but avoid taking it with dairy products, calcium, iron, magnesium, or aluminum preparations within 2 hours, as they can reduce absorption.
- It can cause sun sensitivity (wear sunscreen, protective clothing).
- Stop and seek care if you develop severe diarrhea, allergic reactions, or signs of liver or kidney problems.
If you’re asking about a specific infection or situation (your age, pregnancy status, which country you’re in, other meds, etc.), tell me and I can give you a more tailored summary or help assess what to ask your clinician.