Doxycycline Hyclate Doxyn 100mg 100 Tabs is an antibiotic used for treating bacterial infections.The drug is also sold under the brand names Oracea, Doryx, Monodox, Periostat, and Vibramycin.
Doxycycline is in a class of medications called tetracyclines, and it's a broad-spectrum antibiotic, which means it works against a wide range of bacteria.
Doctors prescribe doxycycline to prevent malaria and treat a wide range of infections, including:Pneumonia and other respiratory tract infectionsLyme diseaseSkin infectionsInfections involving the genitals and urinary tract infections (UTI)Anthrax (after inhalational exposure)Doxycycline works by preventing the growth and spread of bacteria.
Like all antibiotics, doxycycline will not treat colds, the flu, or other infections caused by viruses or fungi.
A 2014 study found that a low dose of 40 milligrams (mg) of slow-release doxycycline daily could be an effective and safe therapy for ocular rosacea, or rosacea that affects the eyes.The drug company Pfizer developed doxycycline in the early 1960s, and the Food and Drug Administration (FDA) approved the drug in 1967 under the brand name Vibramycin.In 1994 the FDA also approved the drug to prevent malaria.
Doxycycline for AcneFor many years, doctors have prescribed doxycycline to treat acne.It's sometimes used as an alternative to another acne drug with more side effects, minocycline. 
However, a study published in 2015 found that people with acne who used an antibiotic-free facial gel had greatly improved acne, according to MedPage Today.
The study suggests that using the facial gel containing adapalene/benzoyl peroxide might be a better alternative than using antibiotics such as doxycycline for acne.
Doxycycline WarningsThere are several important warnings you should know about before taking doxycycline.You should take this medication only to treat bacterial infections, and it's important to take it exactly as your doctor prescribes.Using doxycycline or other antibiotics incorrectly or using them to treat infections caused by other types of germs, such as viruses, contributes to the development of drug-resistant bacteria.Every time you take an antibiotic, it kills the sensitive bacteria. Resistant germs, however, can grow and multiply, and then surviving bacteria can become resistant.It's also important to understand that taking antibiotics, including doxycycline, alters the normal balance of bacteria in your body.In addition to killing harmful bacteria, the medication can also reduce the amount of good bacteria that help keep other germs in check.As a result, some people taking doxycycline develop yeast infections and antibiotic-related diarrhea.Taking doxycycline could make oral birth control pills less effective. If you are on oral contraceptives, you should use other forms of birth control while you take this antibiotic.
Before taking doxycycline, let your doctor know if you're going to have any kind of surgery, including dental surgery.Your doctor also needs to know if you've ever had liver or kidney disease.Also tell your doctor if you have diabetes. Taking doxycycline can interfere with tests for sugar in the urine.Talk with your doctor before changing your diet or your diabetes treatment plan.
Pregnancy and DoxycyclinePregnant women should not take doxycycline because the drug can be harmful to an unborn baby.Tetracyclines, including doxycycline, also pass into breast milk, so women who are breastfeeding should not take this drug.If you're a woman, let your doctor know if you are pregnant, plan to become pregnant, or are breastfeeding.It's also important to note that unborn babies exposed to doxycycline or children younger than 8 years old who take the drug may have permanently stained teeth.Children younger than 8 should not take doxycycline except as treatment for inhalational anthrax or if a doctor decides it's necessary.
Doxycycline for Dogs and CatsDoxycycline is often used to treat bacterial infections in dogs, cats, and other animals. Doxycycline may be prescribed to treat several bacterial infections, such as leptospirosis, urinary tract infections (UTI), toxoplasmosis, erlichiosis, or mycoplasma. It's also used to treat tick-borne diseases, including Lyme disease and Rocky Mountain spotted fever. Because doxycycline can cause severe side effects in dogs and cats (such as nausea and diarrhea), it should be used only under the care and direction of a veterinarian.
Doxycycline Side Effects
Common Side Effects of DoxycyclineCommon side effects of doxycycline include:DiarrheaItching of the rectum or vaginaSore mouthSerious Side Effects of DoxycyclineSerious side effects of doxycycline can also occur.
If you have any of these side effects, stop taking doxycycline and call your doctor right away:Severe headacheBlurry visionRash or hivesTrouble breathing or swallowingSunburnYellowing of the skin or eyesDark-colored urineLight-colored bowel movementsLoss of appetiteNausea or vomitingStomach painExtreme tiredness or weaknessConfusionLess frequent urinationBack to TopDoxycycline InteractionsDoxycycline Drug InteractionsCertain drugs may affect the way doxycycline works. This antibiotic could also interact with other medications.
It's very important to let your doctor know about everything you're taking, including street drugs as well as any over-the-counter (OTC) medications, herbs, or supplements.
Types of drugs that interact with doxycycline include:AntacidsCalcium supplementsIron supplements and laxatives that contain magnesiumPenicillinBlood thinners, such as warfarin (Coumadin)Barbiturates and anti-seizure drugs, such as carbamazepine (Tegretol) and phenytoin (Dilantin)Oral birth control pillsOther Doxycycline InteractionsDoxycycline could upset your stomach.
Taking the drug with milk or food might help, but that may reduce the amount of medication your body can absorb from your stomach.
If you experience an upset stomach while taking doxycycline, talk with your doctor about the best way to take this drug.
Taking doxycycline could also make your skin more sensitive to sunlight. While you are on the medication, be sure to avoid sun exposure whenever possible.
If you do need to be outside, take precautions to protect your skin from the sun, such as:Wearing protective clothing,Wearing sunglassesApplying sunscreenIf you're taking doxycycline to prevent malaria, it's important to understand that the drug does not fully protect you from this infection.
While you are on the drug, you must still take additional preventative measures, including:Applying effective insect repellentUsing mosquito netsWearing clothing that covers your whole bodyDoxycycline and AlcoholIt's possible to drink alcohol while taking doxycycline, but use of alcohol may increase your risk of side effects, including stomach upset. 
Talk with your doctor about the risks of combining alcohol and doxycycline.
Doxycycline DosageDoxycycline comes in tablet, capsule, or liquid form. A doctor also can inject it under your skin.Tablets come in varying strengths including 50, 75, 100, and 150 mg.Don't crush or break a delayed-release capsule.If you're taking an oral form of the drug, drink a full glass of water with each dose.For adults, the normal dose of oral doxycycline is 200 mg on the first day of treatment.Usually you take that as two 100-mg doses, 12 hours apart. After this initial dose, people usually take a maintenance dose of 100 mg daily for seven to 10 days.For more severe infections, such as chronic infections of the urinary tract, the recommended dose is 100 mg every 12 hours.In some cases, people may need to take higher doses, 300 mg a day for 10 days.For inhalational anthrax, the usual adult prescription is 100 mg of doxycycline twice a day for 60 days.For the prevention of malaria, you should start taking doxycycline up to two days before traveling.Continue taking the drug for four weeks after you leave an area where malaria is a risk.Do not take doxycycline to prevent malaria for more than four months.The correct dosage for children older than 8 will depend on the child's weight.Continue to take doxycycline until your course of treatment is finished, even if you feel good.Don't stop taking the medication unless directed by your doctor.
Doxycycline OverdoseDon't take more doxycycline than your doctor prescribed.Taking too much of the medication can increase your risk for developing side effects.If you or someone else has symptoms of an overdose, call a poison control center at 1-800-222-1222.If someone collapses or isn't breathing, call 911.
Missed Dose of Doxycycline Be sure to take doxycycline exactly as your doctor prescribed.Skipping doses or not completing the full course of therapy could make the drug less effective.It could also lead to the development of drug-resistant bacteria ("superbugs") that will not respond to antibiotics in the future.If you forget to take a dose of doxycycline, take the missed dose as soon as you remember it.If it's almost time for your next regular dose, however, skip the missed one.Don't take twice as much doxycycline at one time to make up for a missed dose.