My Lower Leg is Hard and Swollen and Painful After Havig Sclerotherapy 6 Weeks Ago

Please see your physician or go to the ER or Urgent Care.  This may be a clot and it should be taken care of immediately. 

Call your doctor immediately. If it is a small lump it may be localized to one small vessel, it could be a bruise, hematoma but it could be a larger clot with inflammation. If you can't get hold of your doctor you may need to be seen urgently elsewhere, even in an emergency room, to ensure you don't have phlebitis.

One of the more common end results of sclerotherapy for varicose veins is thrombophlebitis. This will manifest itself as hardened superficial veins that are palpable (felt) under the skin. They are superficial because they are palpable. An evaluation with Duplex venous ultrasonography will confirm this and exclude deep vein clots which are not palpable. Deep vein thrombosis may be life threatening. Superficial vein thrombosis is self limited and will improve over time. It is important to follow up with scans to ensure that the superficial vein clots do not extend into the deep veins and cause deep vein clots (deep vein thrombosis). 

If you had larger veins injected, then these veins could clot from the sclerosing solution.  Usually, however, these veins would clot within 72 hours of the treatment. This is not uncommon after sclerotherapy of the bigger veins.  However,  your problem has occurred 6 weeks later and I would be concerned of a clot in a vein.  There are two kinds of clots-superficial and deep.  Superficial is usually less of a concern and is treated with heat and ibuprofen.  Deep phlebitis is worrisome and requires blood thinners.  You should bee seen by your treating physician today or go to the ER  and undergo a venous ultrasound to make the diagnosis and determine treatment.

Please see a physician immediately to rule out thrombosis. This is a clot formation and can be life threatening.

although i do not konw your particular situation i can comment on my patients that i see.

tenderness/swelling/lumpiness of the vein being treated is quite normal and to be expected.  this is one of the pitfalls of foam sclerotherapy compared to say endovenous laser therapy where the vein is permanently and thermally damaged so healing is much quicker and with much less discomfort.

you should follow up with you injecting md to make sure everything is alright.

Cheers