Avidoxy (Doxycycline): Uses, Side Effects, Dosage

By Terez Malka, MD
Medically reviewed checkmarkMedically reviewed
December 28, 2021

Doxycycline is a tetracycline antibiotic that was prescribed more than 21 million times for outpatient conditions in 2019.

It can be used to treat bacterial infections including acne, rosacea, drug-resistance urinary tract infections, and sexually transmitted infections.

Doxycycline is sometimes sold under the brand name Avidoxy.

In this article, I’ll describe how Avidoxy works, when it’s prescribed, and outline its common side effects, dosage, and risks.

I’ll also explain how to take Avidoxy, what to avoid when doing so, and when to talk to your doctor or another healthcare provider.

What is Avidoxy?

Avidoxy is a type of tetracycline-class antibiotic used for treating many different bacterial infections.

It can also be used prophylactically to prevent malaria or sexually transmitted infections, and to treat lyme disease and anthrax exposure.

Doxycycline (Avidoxy) also has anti-inflammatory properties and may help to modulate immune system activity.

For this reason, it is sometimes also used for autoimmune conditions like rheumatoid arthritis. 

Avidoxy works by interfering with bacterial cells’ protein synthesis.

Without these proteins, the bacteria can’t function.

While many antibiotics kill bacteria, Avidoxy prevents bacterial replication, which reduces bacterial numbers, allowing your body to fully fight off the infection. 

Avidoxy is available by prescription only.

Your healthcare provider will determine if Avidoxy is right for you.

If they prescribe it for you, they have decided that any potential side effects do not outweigh the benefits of treatment.

If you are prescribed Avidoxy, it is important to take all of your medication as directed.

If you stop antibiotics without your doctor’s direction, you could increase the risk of recurring infection or may contribute to drug-resistant bacteria.

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Avidoxy Uses


Skin problems aren’t limited to puberty, as many adults know.

Acne vulgaris, rosacea, and other skin problems can be driven by bacteria that live on the surface of your skin.

In some cases, cleansing or topical medications are not enough to resolve this.

Avidoxy is sometimes prescribed in combination with other medications to address acne when your provider feels bacteria are an underlying cause.

Antibiotics for severe acne won’t work overnight.

Avidoxy is often continued for weeks or months when used to treat acne, and it may take two weeks to three months before noticing an improvement..

Urinary tract infections

UTIs are the most common outpatient infection in the U.S., primarily affecting females.

The risk for UTIs increases as you get older.

A UTI can be easily diagnosed with a urine test, and most are treated easily at home with antibiotics.

Avidoxy may be prescribed for urinary tract infections that are caused by bacteria that are resistant to other commonly-used antibiotics, or if you have allergies to other options.

Intestinal infections

While most intestinal infections are due to viruses and get better on their own, bacterial gastroenteritis is treated with antibiotics like Avidoxy..

Bacterial foodborne illness can occur due to raw meat contamination, from bacteria that get into lettuce or other prepared or packaged foods, or may be contracted from unsafe water or food sources while traveling abroad or camping.

Antibiotics can make viral intestinal infections worse, so you should never start an antibiotic for gastrointestinal symptoms unless specifically recommended by your doctor after an appropriate exam and testing.

Respiratory infections

Most respiratory infections—such as colds, bronchitis, and sinus infections—are not caused by bacteria, and antibiotics will not help.

However, sometimes medications like Avidoxy may be used when a bacterial infection develops along with or just after a viral illness.

Starting antibiotics when you have a viral illness will not prevent the development of bacterial infections, so there is no role for starting an antibiotic when you have a viral illness, and no role for the use of antibiotics in the treatment of COVID-19. 

If you do develop certain kinds of bronchitis, sinusitis, or pneumonia caused by bacteria, you may notice cough or cold symptoms getting worse 7-10 days after the start of your symptoms or the development of a new, high fever 5-10 days into your illness.

In this case, antibiotics like Avidoxy may be recommended depending on the type of infection you have, after appropriate exam and testing. 

Eye infections

Many eye infections, such as conjunctivitis (“pink eye”), are viral and will go away on their own.

Your doctor can help you figure out if your infection is caused by a bacteria and requires antibiotic treatment.

Most bacterial eye infections can be effectively treated with antibiotic drops or ointment, but some more severe infections may require an oral antibiotic, like Avidoxy.

Avidoxy may also be prescribed if you have an eye infection due to the sexually transmitted infection chlamydia. 

Sexually transmitted infections (STIs)

Sexually transmitted infections like chlamydia, gonorrhea, or syphilis can cause unpleasant symptoms and other health side effects.

Chlamydia can result in co-occurring eye infections as well.

Antibiotics like Avidoxy are used to treat STIs and may also be used as prophylaxis to reduce the risk of developing an infection in those who are at risk.

Periodontitis (gum disease)

Two out of every five adults in the U.S. are affected by gum disease, also known as periodontitis.

Left untreated, periodontal disease can negatively impact cardiovascular health.

Gum disease can be addressed by Avidoxy and other tetracycline-class antibiotics.

A low dose of Avidoxy works to decrease the number of harmful bacteria in the mouth without otherwise destroying the beneficial bacteria that are part of the oral microbiome.

If your gums bleed easily or are sensitive, these could be signs that you have gum disease, and should be discussed with your dentist.


A mosquito-borne illness, malaria is still a significant public health problem in certain parts of the world.

Avidoxy can be given preventively if you will be traveling to areas where malaria is common.

It can also be used to treat malaria infections when paired with other medicines.

Avidoxy Side Effects

Common Avidoxy side effects that may be normal include:

In rarer cases, patients may have a more serious reaction to a medication.

If you notice any of these side effects while taking Avidoxy, check in with your doctor or pharmacist right away:

Avidoxy is typically not prescribed for younger children.

A child under age 8 may be at risk for permanent tooth staining or other complications.

Pregnant women, particularly those who are in the second half of pregnancy, should not take Avidoxy, as the unborn child’s teeth could also be impacted.

If you are pregnant or think you could be pregnant, make sure your prescriber knows.

If you are allergic to tetracycline antibiotics, you should not take Avidoxy.

Avidoxy may affect how birth control pills work.

It can also interact with other medications, including:

  • Anticoagulants (blood thinners)
  • Penicillin
  • Antacids
  • Iron supplements
  • Magnesium
  • Anti-epileptics

Keep your doctor informed about any medications that other doctors may have prescribed, as well as any OTC medications or supplements that you take.

How to Take Avidoxy

Dosage and administration

Avidoxy doses can range from 20 mg of doxycycline to a maximum daily dose of 600 mg.

Your doctor or dentist will determine the right dose for your condition.

Your prescription label will explain how much you should take. Read your prescription instructions carefully.

What happens if I miss a dose?

Don’t panic if you miss a dose.

If you are within a few hours of your missed dose, take it and adjust your next dose accordingly.

Do not double up on doses or take them closer together.

If you completely miss a dose, skip it and continue your plan. If you have questions or concerns about a missed dose, ask your healthcare provider or call your pharmacy.

What happens if I take too much?

Taking one extra dose of Avidoxy is unlikely to cause any harm, but if you do take significantly more than you were prescribed, or experience any symptoms, you should contact poison control at 1-800-222-1222, and have your prescription information ready.

If you are with someone who has taken too much Avidoxy, seek emergency medical care if they are unconscious, struggling to breathe, or have a seizure.

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What to Avoid While Taking Avidoxy

Dairy products may interfere with how Avidoxy absorbs, so eat them a few hours before or after your dose.

Drink a full glass of water with your medication and stay hydrated throughout the day.

Do not use tanning beds or spend time in the sun when taking Avidoxy.

If you are in the sun, wear sunscreen and protective clothing, as this medication increases the risk of severe sunburn.

Most medical advice says to avoid alcohol while taking antibiotics.

Drinking alcohol while taking Avidoxy can make the medication less effective, and should be avoided until 48-72 hours after your last dose. 

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Frequently Asked Questions

What are the side effects of Avidoxy?
Common side effects of Avidoxy are similar to other antibiotics. You may notice changes to bowel movements, experience nausea, or feel a sore throat. If you have symptoms that concern you, speak to your doctor or provider right away.
What is doxycycline used to treat?
Doxycycline is a broad-spectrum antibiotic used to treat drug-resistant UTIs, sexually transmitted infections, malaria, and more. It may also be used to prevent or treat Lyme disease after a tick bite and can be used in case of anthrax exposure.
What is tetracycline used for?
Tetracycline is the name of a tetracycline-class antibiotic. Like doxycycline, it is used to treat many common bacterial infections like acne, sexually transmitted infections, malaria, and Lyme disease.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.

Terez Malka, MD

Dr. Terez Malka is a board-certified pediatrician and emergency medicine physician.

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