Swollen vein right forearm.....tender when pressed....harder than it should be.....

Possible phlebitis?: What you describe could be superficial phlebitis. Have you had a recent blood draw or IV these are common causes of this superficial phlebitis in the forearm. Check with a doctor. often this can be treated with warm compress and it gets better on its own.

Swollen arm vein.: A swollen, tender vein is always cause for concern and suggests inflammation of the vein called thrombophlebitis. This could be the result of trauma, needle insertion or iv's. The initial treatment is elevation, heat to the area and antibiotics. Thrombophlebitis can occur in any vein and is most common in the arms or legs. See a vein specialist.