Siadocin (Doxycycline 100 mg HCl) is a tetracycline antibiotic that inhibits bacterial protein synthesis. Used to treat inflammatory acne, respiratory infections, and sexually transmitted infections. 10 capsules per box | Manufactured by Siam Bheasach Co., Ltd., Bangkok, Thailand.
Doxycycline 100 mg is a broad-spectrum tetracycline antibiotic used for inflammatory acne, respiratory tract infections, and sexually transmitted infections. It works by binding to the bacterial 30S ribosomal subunit, blocking protein synthesis and stopping bacterial growth (bacteriostatic mechanism). Siadocin contains 100 mg Doxycycline HCl per capsule, manufactured by Siam Bheasach Co., Ltd. in Bangkok (Reg. No. 1A 145/39), approved by Thailand's Food and Drug Administration.
📊 Clinical evidence: Doxycycline reduces inflammatory acne lesions by 50–60% within 12 weeks (PubMed/JAAD). It is a first-line treatment for Chlamydia (most reported STI in Thailand, DDC 2023), Syphilis in penicillin-allergic patients, atypical pneumonia (Mycoplasma, Chlamydophila), and Lyme disease.
Doxycycline 100 mg should always be used as directed by a doctor or pharmacist. General adult dosages are as follows:
Common Dosages
Inflammatory acne: 100 mg once daily for 6–12 weeks
Respiratory tract infections: 100 mg once or twice daily as prescribed
STDs (Chlamydia, Syphilis): 100 mg twice daily for 7–14 days
How to Take
Take with or after food to reduce nausea
Drink at least 240 ml of water with each dose
Do not lie down within 30 minutes of taking (prevents esophageal ulceration)
Avoid milk, calcium supplements, and antacids within 2 hours before or after dosing (chelation reduces absorption)
Avoid prolonged sun exposure; use SPF 30+ sunscreen while on treatment
⚠️ Complete the full course even if symptoms improve.
Indications & Uses
Doxycycline 100 mg is approved for the following indications:
1. Inflammatory Acne
An effective oral antibiotic for acne that reduces Cutibacterium acnes and suppresses inflammation simultaneously. Indicated for moderate-to-severe inflammatory acne unresponsive to topical treatments.
2. Respiratory Tract Infections
Treats atypical pneumonia (Mycoplasma pneumoniae, Chlamydophila pneumoniae) and chronic bronchitis.
3. Sexually Transmitted Infections (STI)
First-line treatment for Chlamydia, gonorrhea (non-penicillinase-producing strains), and syphilis in penicillin-allergic patients.
4. Other Infections
Lyme disease (tick-borne)
Rickettsia infections
Malaria prophylaxis
Side Effects & Precautions
Common Side Effects
Nausea, vomiting, or stomach upset (reduced by taking with food)
Photosensitivity — avoid prolonged sun exposure
Diarrhea
Headache, dizziness
Skin rash
Less Common but Important
Esophageal ulceration — prevented by drinking plenty of water and not lying down
Vaginal yeast infection
Pseudomembranous colitis (rare)
Contraindications
Children under 8 years (risk of tooth discoloration and bone effects)
Pregnancy and breastfeeding
Known hypersensitivity to tetracyclines
Drug Interactions
Doxycycline has clinically important interactions with several medications and substances.
Substances That Reduce Doxycycline Absorption
Antacids (aluminum/magnesium) — space at least 2 hours apart
Iron supplements / Calcium — chelation significantly reduces absorption
Milk / Dairy — high calcium; take 2 hours apart
Bismuth subsalicylate
Other Key Interactions
Warfarin — may enhance anticoagulant effect; monitor INR closely
Oral contraceptives — may reduce efficacy; use backup contraception
Penicillins — avoid combining (bacteriostatic vs bactericidal antagonism)
Retinoids (e.g. isotretinoin) — increased risk of intracranial hypertension
Comparing Oral Antibiotics
Oral antibiotics differ in spectrum and indication. Here is a quick comparison:
Siadocin — Doxycycline 100 mg
Best for: inflammatory acne, atypical pneumonia, STIs (Chlamydia, syphilis), Lyme disease | Tetracycline class | bacteriostatic
Best for: anaerobic infections, Trichomoniasis, Giardia, bacterial vaginosis | bactericidal vs anaerobes
Summary: Siadocin (Doxycycline) is the first choice for oral acne treatment and Chlamydia/Syphilis STIs. Amoxicillin covers Gram-positive infections; Ciprofloxacin targets Gram-negative organisms.
Manufacturer & Registration
Manufacturer
Siam Bheasach Co., Ltd. Bangkok, Thailand
Drug Registration
Registration No.: 1A 145/39
Dosage Form
Form: Capsule
Strength: 100 mg Doxycycline HCl per capsule
Pack size: 10 capsules per box
Storage
Store in a dry place below 30°C, away from direct sunlight. Keep out of reach of children.
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Intimo Life stocks authentic Siadocin (Doxycycline 100 mg) with nationwide delivery across Thailand. Orders are shipped in plain, discreet packaging—no product name shown. Available to order 24/7.
Doxycycline 100 mg treats inflammatory acne, atypical respiratory infections (Mycoplasma, Chlamydophila pneumoniae), sexually transmitted infections (Chlamydia, Syphilis), Lyme disease, and is used for malaria prophylaxis. It is a broad-spectrum tetracycline antibiotic that inhibits bacterial growth.
Take Doxycycline with or right after food to minimize nausea. Always drink at least 240 ml of water with each dose. Do not lie down for at least 30 minutes after taking.
Common side effects include nausea, increased sun sensitivity (photosensitivity), diarrhea, and headache. A less common but important risk is esophageal ulceration, prevented by drinking plenty of water and staying upright after taking.
Avoid milk and dairy products within 2 hours before or after taking Doxycycline. Calcium in dairy forms a chelate complex with the drug, significantly reducing its absorption into the bloodstream.
Most people see a reduction in inflammatory acne lesions within 4–6 weeks, with maximum benefit around 12 weeks. Studies report 50–60% lesion reduction at 12 weeks. It is typically combined with topical treatments as recommended by a dermatologist.
Doxycycline is contraindicated in children under 8 years (risk of permanent tooth discoloration), pregnant women, breastfeeding mothers, and anyone with a known allergy to tetracyclines.
Siadocin is the brand name for Doxycycline 100 mg manufactured by Siam Bheasach Co., Ltd., an FDA-approved Thai pharmaceutical company. The active ingredient and dosage strength are identical to generic Doxycycline.
Key interactions include: Warfarin (enhanced anticoagulation — monitor INR), oral contraceptives (reduced efficacy — use backup), retinoids like isotretinoin (risk of intracranial hypertension), and antacids/iron supplements (reduced absorption).
Oral Doxycycline works systemically (throughout the body), making it suitable for moderate-to-severe or widespread inflammatory acne. Topical antibiotics (e.g. Clindamycin gel) act locally and are better for mild-to-moderate acne. Dermatologists often combine both for optimal results.
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