How long should it take for achilles tendonitis to heal completely?

Depends: On the severity of the injury and the amount of swelling. Achilles tendinitis is difficult to treat because of low blood flow through the tendon above the insertion to the heel called the watershed area. Ruptures usually occur at this location. If not severe, it takes 4 weeks to heal with rest and ice and physical therapy. If there is a bulbous swelling of the tendon it can take months to heal.

8 months: It takes approximately 8 months for any tendon or ligament in the adult body to completely heal if it is not re-injured during the recovery time.