A 23 year-old man was admitted to the hospital with chief complaints of pain, edema and spasm of the left lower limb, as well as mottling of dorsal and plantar aspects of the foot. One week before the current admission, he was treated with oral co-amoxiclave and intramuscular penicillin 6.3.3. Immediately after the third injection, he experienced burning and yellowish discoloration at the site of the injection wich then progressed to his leg and foot. Pain, significant edema, spasm and mottling occurred within 30 minutes of the injection. The patient was referred to the hospital after 36 hours from the beginning of the symptoms. Color Doppler sonography revealed no impairment in the lower extremity flow and the common femoral artery, superficial femoral, popliteal, dorsalis pedis and posterior tibialis arteries were normal. Superficial probe sonography detected mild effusion in the left ankle without collection.