The MUFFIN-PTS Trial

Inclusion Criteria: * Villalta score ≥5 with at least two of the following four PTS manifestations (daily heaviness, cramps, pain, and objective edema) in the leg ipsilateral to a previous objectively diagnosed DVT, or DVT of unknown date but with presence of residual proximal or distal venous obstruction on ultrasound. Females of childbearing age must use medically approved method of birth control and must have negative pregnancy test results at the time of randomization. Exclusion Criteria: * Recent acute ipsilateral DVT (\<3 months) * Active ipsilateral venous ulcer * Acute or chronic altered mental status * Any venoactive drug intake within 3 months of the start of the study * Allergy or hypersensitivity to MPFF/Venixxa * Age\<18 years * Pregnant or breastfeeding women * Life expectancy \<1 year * Refuse or unwilling to provide consent * Unable to speak English or French * Alcohol/drug abuse * Hospitalized patients * End-stage kidney disease (dialysis, creatinine clearance \< 10ml/min) * Liver cirrhosis Child-Pugh class C. * Currently enrolled in other clinical trials, other than trials of prevention or treatment of venous thromboembolism