Why Do HHT Patients Need Antibiotics for Dental Work?

If you have Hereditary Hemorrhagic Telangiectasia (HHT), you may have been told to take antibiotics before going to the dentist. This requirement can seem confusing, especially since it is completely different from why most other people take antibiotics. For HHT patients, taking antibiotics before dental cleanings or procedures is not about protecting your teeth or gums—it is about protecting your brain. The reason comes down to the unique way HHT affects the blood vessels in your lungs.

The Missing Filter: How Lung AVMs Affect Your Body

To understand why antibiotics are necessary, it helps to look at how a healthy circulatory system works. Normally, when small amounts of bacteria enter your bloodstream—which commonly happens during a routine dental cleaning or tooth extraction—your blood eventually flows through the lungs. The lungs are filled with a vast network of tiny blood vessels called capillaries. These capillaries act like a microscopic filter, trapping bacteria and small blood clots so your body’s immune system can destroy them before they reach the rest of your body.

However, HHT often causes abnormal blood vessel connections known as pulmonary arteriovenous malformations (PAVMs) ^[1][2]. A PAVM is a direct, tangled connection between an artery and a vein in the lung that skips the capillary network entirely ^[3][4].

Because this capillary filter is missing, bacteria from your mouth can bypass the lungs and enter your systemic blood circulation ^[3][5].

The Risk of Brain Abscesses

When bacteria bypass the lung’s filter through a PAVM, they have a direct pathway to your brain ^[5]. If these oral bacteria settle in the brain tissue, they can multiply and form a brain abscess (a life-threatening pocket of infection) ^[6][3]. In fact, for some patients, a brain abscess is the very first warning sign that they have HHT or a lung AVM ^[5][7].

Taking a prophylactic (preventative) antibiotic before dental procedures significantly reduces the number of live bacteria in your bloodstream, minimizing the risk of this severe neurological complication.

Which Procedures Require Antibiotics?

You do not need antibiotics for every single visit to the dentist. Prophylaxis is required for procedures that involve manipulating gum tissue or perforating the oral mucosa ^[3][8]. This includes:

• Routine professional teeth cleanings
• Tooth extractions
• Root canals
• Deep scaling or root planing

You generally do not need antibiotics for routine visual exams, taking dental X-rays, or adjusting braces, as these do not force bacteria into the bloodstream.

Who Needs Antibiotics?

While current international guidelines acknowledge this as an area needing more standardized research ^[9][10], clinical consensus across HHT Centers of Excellence strongly recommends antibiotic prophylaxis for:

• Anyone with known pulmonary AVMs. ^[11]
• Anyone with HHT who has not yet been screened for pulmonary AVMs. (Because you must assume a PAVM is present until a screening proves otherwise).
• Anyone who has had their pulmonary AVMs treated (embolized). Even after successful treatment, PAVMs can sometimes reopen (reperfusion) or new ones can form, meaning the risk of a bypassed filter remains ^[12][13].

Standard Antibiotic Protocols

The standard antibiotic protocol for HHT patients generally mirrors the American Heart Association (AHA) guidelines used to prevent heart valve infections (endocarditis). The typical recommendation is:

• Standard Dose: A single 2-gram dose of Amoxicillin (for adults) taken by mouth 30 to 60 minutes before the dental procedure ^[8].
• If You Are Allergic to Penicillin: Your doctor or dentist will prescribe a safe alternative in accordance with current AHA guidelines, such as Cephalexin, Azithromycin, or Clarithromycin ^[8]. (Note: Clindamycin was removed from AHA guidelines in 2021 and is no longer recommended).

Advocating for Yourself at the Dentist

Many dentists are unfamiliar with HHT and might be hesitant to prescribe antibiotics for a condition they don’t know. If you face pushback, you can explain it like this:

“I have a condition that causes a right-to-left shunt in my lungs, which skips my body’s natural bacterial filter. Because of this, standard endocarditis prophylaxis is required to prevent brain abscesses.”

It is often incredibly helpful to ask your HHT specialist for a brief, formal letter explaining your diagnosis and the necessity of dental antibiotics. You can keep this letter on file at your dentist’s office. Always make sure you have your prescription filled and ready before the day of your appointment.