Trench foot is often categorized into one of four stages, including:
Stage 1—Injury Phase
This stage involves restriction of the blood flow due to cold tissue, symptoms may include numbness and reddened skin, but pain has not yet begun.
Stage 2—Pre-hyperaemic Phase
This stage lasts from six to 24 hours. Symptoms include pale, white-colored, cold feet with paraesthesia (pins and needles sensation). The ankles and toes are stiff, making it difficult to walk.
Upon examination, a healthcare provider may not be able to palpate (feel) the normal pulses of the feet (indicating that normal blood flow has been impeded).
Stage 3—Hyperaemic Phase
This phase lasts up to two months. Symptoms include painful feet that are hot the touch. There is swelling that worsens with heat, movement, and standing.
In severe cases, small blisters may be seen. Bruising, along with petechiae (rash-like spots on the skin) may be present. When trench foot is mild, the condition usually resolves with treatment at this stage. If it is severe, trench foot symptoms progress.
Stage 4— Post-Hyperaemic Phase
This phase may last for the duration of the person’s life. This is a long-term vasospastic (narrowing of the blood vessels) phase involving increased pain on warming, hyperhidrosis (extreme and excessive sweating) of the feet, and paresthesia (pins and needles sensation).
The affected foot/feet may develop a sensation of being cold, permanently. Secondary Raynaud’s syndrome (a condition involving an exaggerated sensitivity to cold in which the toes turn blue and/or white upon exposure to cold, and then bright red on rewarming) develops as a result of long-term constriction of small blood vessels.
A 2013 study, reports that trench foot usually starts with tingling and itching which progresses to numbness. Restricted blood flow can cause reddened skin and a bluish discoloration (called cyanosis). In the later stages, as the foot is rewarmed, hyperesthesia (excessive physical sensation) may occur.
Odor, decay and necrosis (death of tissue) may occur with prolonged exposure. The feet can swell in some instances significantly; in fact, there are some descriptions of the feet doubling in size due to edema (swelling).