Doxysina100 mg

Respiratory Tract Infections

Doxysina is an established treatment option for community-acquired bacterial respiratory infections caused by susceptible organisms, including infections due to Mycoplasma pneumoniae, Chlamydophila psittaci, and susceptible strains of Streptococcus pneumoniae and Haemophilus influenzae, such as bronchitis, sinusitis, and community-acquired pneumonia in appropriate patients.

Sexually Transmitted Infections

Doxysina is guideline-supported first-line therapy for uncomplicated genital, rectal, and pharyngeal chlamydial infections caused by Chlamydia trachomatis. It is also an alternative treatment for early and late-stage syphilis in patients who cannot take penicillin. For gonorrhea, current treatment guidance relies on ceftriaxone as monotherapy; Doxysina is added only when chlamydial coinfection has not been ruled out, and Doxysina is not considered adequate monotherapy for gonococcal infection on its own.

Doxysina is also used, per CDC 2024 clinical guidance, as post-exposure prophylaxis ("doxy-PEP") to reduce the risk of chlamydia and syphilis (and, in some studies, gonorrhea) in specific adult populations, such as gay and bisexual men and transgender women with a bacterial sexually transmitted infection in the preceding 12 months, taken within 72 hours after condomless sex. This use of Doxysina is a public-health prevention strategy rather than treatment of an existing infection, and Doxysina is not indicated for this purpose in adolescents or in the general population.

Rickettsial and Vector-Borne Infections

Doxysina is the established drug of choice for Rocky Mountain spotted fever and other tickborne rickettsial diseases (including ehrlichiosis, anaplasmosis, typhus, Q fever, and rickettsialpox), and Doxysina is recommended by the CDC and the American Academy of Pediatrics for patients of all ages, including children under 8 years and pregnant women, because delayed treatment carries a substantially higher risk of severe illness or death than the medicine itself.

Zoonotic and Other Systemic Bacterial Infections

Doxysina is established therapy for plague (Yersinia pestis), tularemia (Francisella tularensis), brucellosis (usually in combination with an aminoglycoside or rifampin — combination therapy is required for optimal cure in brucellosis, not Doxysina alone), cholera (Vibrio cholerae), and relapsing fever (Borrelia recurrentis). Doxysina is also used, as an alternative to penicillin, for infections such as anthrax, including post-exposure prophylaxis following suspected inhalational anthrax exposure, and as an adjunct in the treatment of acute intestinal amebiasis (used together with an amebicidal agent, not as monotherapy).

Skin and Acne-Related Conditions

Doxysina is used as an adjunctive treatment for moderate to severe inflammatory acne vulgaris and for rosacea, generally as part of a broader skin-care regimen and typically for a limited, defined course rather than indefinite use, in line with current antibiotic stewardship practice.

Malaria Prophylaxis

Doxysina is a guideline-supported option for short-term malaria chemoprophylaxis (generally less than 4 months of travel) in travelers to areas with chloroquine- or pyrimethamine-resistant malaria, in patients aged 8 years and older.

Doxycycline Hydrochloride is well absorbed after oral administration, and unlike some older tetracyclines, absorption of Doxycycline Hydrochloride is not markedly reduced by food in general, although co-administration with dairy products, antacids, or iron/calcium/magnesium-containing preparations can still reduce absorption of Doxycycline Hydrochloride through chelation. Doxycycline Hydrochloride is widely distributed throughout body tissues and fluids and is highly protein-bound in plasma. Doxycycline Hydrochloride undergoes minimal hepatic metabolism and is eliminated mainly through biliary/fecal excretion as a chelated, biologically inactive form, with a smaller portion excreted unchanged in urine. The elimination half-life of Doxycycline Hydrochloride (approximately 18–22 hours) is not significantly altered by renal impairment, and hemodialysis does not meaningfully change its serum half-life.

• Swallow Doxysina capsules/tablets whole with a full glass of water; do not crush, chew, or break them unless the tablet is scored for that purpose.
• Remain sitting or standing (do not lie down) for at least 30–60 minutes after taking Doxysina to reduce the risk of esophageal irritation or ulceration.
• Avoid taking Doxysina immediately before bedtime.
• Doxysina may be taken with food or milk if stomach upset occurs; however, where possible, avoid taking Doxysina at the same time as dairy products, calcium, iron, or antacids, and separate dosing by at least 2 hours, since these can reduce absorption.
• Use effective sun protection (sunscreen, protective clothing) and limit prolonged sun/UV exposure, as Doxysina can increase sensitivity to sunlight.
• Take Doxysina exactly as prescribed; do not stop, extend, skip, or share Doxysina without medical advice, even if symptoms improve early.

• Antacids, calcium, magnesium, bismuth subsalicylate, and iron-containing products: these form insoluble complexes (chelates) with Doxysina in the gut, substantially reducing absorption of Doxysina; separate dosing by several hours where possible.
• Warfarin and other anticoagulants: Doxysina may potentiate anticoagulant effect, requiring closer monitoring and possible dose adjustment of the anticoagulant.
• Penicillin-class antibiotics: the bacteriostatic action of Doxysina may interfere with the bactericidal action of penicillins; concurrent use of Doxysina with penicillins is generally avoided.
• Hormonal (oral) contraceptives: Doxysina may reduce contraceptive efficacy; patients should be advised to consider an additional or backup contraceptive method while taking Doxysina.
• Barbiturates, carbamazepine, and phenytoin: these enzyme-inducing drugs can shorten the half-life of Doxysina, potentially reducing its effectiveness.
• Isotretinoin: concurrent use of isotretinoin with Doxysina increases the risk of intracranial hypertension (pseudotumor cerebri); concurrent use should be avoided.

Common Side Effects

• Nausea, vomiting, and diarrhea
• Abdominal discomfort or loss of appetite
• Photosensitivity (increased sunburn-type skin reaction)
• Mild skin rash

Serious Side Effects (Seek Medical Attention)

• Severe or persistent watery/bloody diarrhea, which may indicate Clostridioides difficile-associated diarrhea or colitis
• Severe headache, blurred or double vision, or vision loss, which may indicate intracranial hypertension (pseudotumor cerebri) — see Precautions and Warnings for details
• Severe chest pain or pain/difficulty swallowing, which may indicate esophageal irritation or ulceration — see Precautions and Warnings for details
• Yellowing of the skin or eyes, dark urine, or unusual tiredness, which may indicate liver injury
• Severe skin reactions such as blistering, peeling skin, or widespread rash (possible Stevens-Johnson syndrome, toxic epidermal necrolysis, or DRESS syndrome)
• Signs of a severe allergic reaction such as swelling of the face/throat or difficulty breathing
• Unusual bruising, bleeding, tiredness, or pallor, which may rarely indicate a blood disorder such as hemolytic anemia

Pregnancy

Data specifically on Doxysina in pregnancy are limited, but a large Swedish population-based cohort study of tetracycline-class antibiotics (in which Doxysina accounted for the large majority of exposures) found no increased risk of major congenital malformations following first-trimester exposure. However, manufacturer prescribing information continues to caution that use during the second and third trimesters, when fetal teeth and bones are developing, may cause permanent tooth discoloration and reversible inhibition of bone growth; this caution reflects a known class effect of tetracyclines rather than an outcome specifically documented for Doxysina alone. For this reason, Doxysina is generally avoided in pregnancy, especially from the second trimester onward, unless no suitable alternative exists. An important exception is serious, potentially life-threatening infection such as Rocky Mountain spotted fever and other tickborne rickettsial diseases, for which the CDC recommends Doxysina as first-line treatment in pregnant women in all trimesters, because the risk of severe maternal and fetal harm from untreated infection outweighs the theoretical risks of Doxysina. Any use of Doxysina in pregnancy should be individually assessed by a qualified healthcare professional.

Breastfeeding

Doxysina passes into breast milk. Manufacturer labeling advises against breastfeeding during treatment with Doxysina and for 5 days after the last dose of Doxysina, due to the potential for tooth discoloration and effects on bone growth in the infant, although this has not been firmly quantified. Mothers who need Doxysina for a serious infection should discuss the risks, benefits, and alternative options with their healthcare provider.

• Photosensitivity: Doxysina can cause an exaggerated sunburn-like skin reaction; patients should limit sun/UV exposure and use sun protection while taking Doxysina, and should stop the medicine and seek advice if skin redness or burning develops.
• Esophageal irritation and ulceration: take Doxysina with plenty of water, remain upright afterward, and avoid bedtime dosing to reduce the risk of throat or chest pain or difficulty swallowing.
• Clostridioides difficile-associated diarrhea (CDAD): as with almost any antibiotic, Doxysina can disturb normal gut bacteria and allow overgrowth of C. difficile, causing diarrhea or colitis ranging from mild to severe; seek medical advice for persistent or severe diarrhea, even weeks after stopping Doxysina.
• Intracranial hypertension (pseudotumor cerebri): tetracycline-class drugs including Doxysina have been associated with raised pressure around the brain, more often in women of childbearing age who are overweight or have a prior history of this condition; symptoms include severe headache and visual disturbance. Concurrent use of Doxysina with isotretinoin increases this risk and should be avoided.
• Tooth and bone effects in developing teeth/bones: use of Doxysina during tooth development (second half of pregnancy, infancy, and childhood) may cause permanent tooth discoloration and reversible effects on bone growth; see Pregnancy and Lactation and Use in Special Populations for how this is weighed against the seriousness of the infection being treated.
• Hepatotoxicity: liver injury has been reported with tetracycline-class antibiotics, including Doxysina; use Doxysina with caution in patients with pre-existing liver disease or those taking other medicines that can affect the liver.
• Severe skin reactions: rare but serious reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, and DRESS syndrome have been reported with Doxysina; discontinue Doxysina immediately and seek urgent medical attention if severe rash, blistering, or skin peeling occurs.
• Superinfection: prolonged use of Doxysina may lead to overgrowth of non-susceptible organisms, including fungal infections; report new symptoms to a healthcare professional.
• Not effective against viral infections: Doxysina treats bacterial infections only and has no effect on viruses such as those causing the common cold or influenza; unnecessary use of Doxysina contributes to antibiotic resistance.

Reported effects of Doxysina overdose are generally an extension of the common side effects of Doxysina, particularly nausea, vomiting, diarrhea, and irritation or ulceration of the esophagus and stomach, especially if taken with too little water. No specific antidote for Doxysina overdose exists. If an overdose of Doxysina is suspected, do not induce vomiting unless specifically directed to do so by a doctor or poison control service; contact emergency medical services or a poison control center immediately for guidance. Management of Doxysina overdose is generally supportive and symptomatic; hemodialysis does not significantly change blood levels of Doxysina and is not expected to be beneficial in overdose.

Store Doxysina according to the storage instructions printed on the product packaging or leaflet, as these can vary between manufacturers and formulations. As a general precaution, keep Doxysina at room temperature, away from direct sunlight, excessive heat, and moisture, in its original, tightly closed container, and out of the reach and sight of children. Do not use Doxysina beyond its expiry date.

Children

For most non-severe infections, manufacturer labeling advises using Doxysina in children 8 years of age or younger only when the potential benefits are expected to outweigh the risk of tooth discoloration and reversible effects on bone growth, and when no suitable alternative treatment exists. However, current CDC and American Academy of Pediatrics guidance carves out a specific exception for serious, potentially life-threatening infections such as Rocky Mountain spotted fever and other tickborne rickettsial diseases: Doxysina is recommended as first-line treatment for children of all ages, including under 8 years, because short courses (typically 5–10 days, generally under 21 days) have not been shown to cause staining of permanent teeth or enamel defects, and delaying treatment carries a far greater risk than Doxysina itself. This exception applies to short, indication-specific courses of Doxysina for serious infections and should not be read as removing caution around routine or prolonged pediatric use. Malaria prophylaxis with Doxysina is indicated from age 8 years and older; Doxysina post-exposure prophylaxis (doxy-PEP) for STI prevention is an adult-only recommendation and has not been established in adolescents or children.

Elderly

No specific dose adjustment of Doxysina is established for older adults on the basis of age alone; standard adult dosing of Doxysina is generally used. Older patients, particularly those with swallowing difficulties or reduced mobility, should be reminded to take Doxysina with plenty of water and to remain upright afterward to reduce the risk of esophageal irritation.

Renal Impairment

Studies have shown no significant difference in the elimination half-life of Doxysina between patients with normal kidney function and those with severe renal impairment, and hemodialysis does not meaningfully alter the half-life of Doxysina; a specific dose reduction of Doxysina for renal impairment is not established in the sources reviewed, but patients with renal disease taking Doxysina should still be monitored by their prescriber.

Hepatic Impairment

Specific dose-adjustment guidance for Doxysina in hepatic impairment is not established in the prescribing information reviewed. Because rare hepatotoxicity has been reported with Doxysina and other tetracyclines, Doxysina should be used with caution and with monitoring in patients who have pre-existing liver disease or who are taking other medicines that can affect the liver.

Pregnant and Breastfeeding Women

See the Pregnancy and Lactation section above for detailed guidance on the use of Doxysina in this population.

Women of Childbearing Age Who Are Overweight

This group has a higher reported risk of intracranial hypertension with tetracycline-class drugs including Doxysina; see Precautions and Warnings for details.

The duration of treatment with Doxysina is set by the prescriber and depends entirely on the indication being treated: for example, a single dose of Doxysina for post-exposure prophylaxis (doxy-PEP); 5–7 days (continuing at least 3 days after fever resolves) for rickettsial diseases such as Rocky Mountain spotted fever; 7 days for uncomplicated chlamydial infection; 14 days for early syphilis and 28 days for syphilis of more than one year's duration (as alternatives to penicillin); 60 days for inhalational anthrax post-exposure prophylaxis; and daily dosing of Doxysina throughout travel plus 4 weeks afterward for malaria prophylaxis. For acne and rosacea, courses of Doxysina are typically limited and periodically reassessed rather than continued indefinitely, consistent with current antibiotic stewardship practice. Patients should take Doxysina for exactly as long as prescribed and should not stop, extend, or repeat a course of Doxysina without medical advice.

Doxycycline Hydrochloride is a bacteriostatic antibiotic. Doxycycline Hydrochloride binds reversibly to the 30S ribosomal subunit of susceptible bacteria, blocking the binding of aminoacyl-tRNA to the mRNA-ribosome complex. This prevents the addition of amino acids to the growing peptide chain, inhibiting bacterial protein synthesis and thereby stopping bacterial growth and multiplication without directly killing the organism.

Dosing of Doxysina in children is weight-based for those under 45 kg; children weighing 45 kg or more are generally dosed using adult regimens of Doxysina. For severe or life-threatening infections such as Rocky Mountain spotted fever and other tickborne rickettsial diseases, the CDC and American Academy of Pediatrics recommend 2.2 mg/kg of Doxysina given every 12 hours, for patients of all ages including children under 8 years, because short courses (generally under 21 days, and typically only 5–10 days for this indication) have not been shown to cause staining of permanent teeth, and because delayed treatment carries a much higher risk of severe illness or death. For non-severe infections in children 8 years of age or younger, current manufacturer labeling still advises use of Doxysina only when benefits are judged to outweigh the risk of tooth discoloration and reversible bone growth effects, and when no suitable alternative exists; in children older than 8 years, these concerns are substantially reduced. For malaria prophylaxis, Doxysina is indicated from age 8 years and older, dosed at 2 mg/kg once daily (up to the adult dose) for children under 45 kg. Doxysina post-exposure prophylaxis (doxy-PEP) for sexually transmitted infection prevention is an adult-specific recommendation and is not established for adolescents or children. Any pediatric use of Doxysina should be guided by a pediatrician or qualified healthcare professional weighing the specific indication and the child's age.