Table 1 Inclusion and exclusion criteria

Age > = 18

Clinical HHT diagnosis or genetic diagnosis of HHT

Epistaxis at least 15 min per week (mean for past month)

At least one telangiectasia (skin or mucosal) available for micro-imaging

Ability to give written informed consent

Allergy/intolerance to the study drug or related agents

Unstable medical illness

Acute infection

Creatinine > ULN (upper limit of normal)

Liver transaminases (AST or ALT) > = 2 × ULN

Recent (within 2 months) use of study drug or other tetracycline agents

Women who are pregnant or breastfeeding or plan to become pregnant during the study

BHCG level>6IU/L (re-test if 6-24 IU/L)

Specific contra-indications for study drug

On blood thinner AND refuses to have family doctor notified of study participation