Why do my feet swell up when I wake up in the morning?

Swelling in the feet upon waking up in the morning can have several possible causes, including:

1. Prolonged standing or sitting: If you stood for long periods or remained sedentary the previous day, it may lead to poor circulation in the lower limbs, causing fluid accumulation in the tissue spaces and resulting in foot swelling.

2. Lower limb venous disease: Conditions such as varicose veins or deep vein thrombosis may impair venous return and cause foot swelling.

3. Metabolic diseases: Gout can also cause redness, swelling, and increased pain in the foot.

4. Autoimmune diseases: Conditions such as rheumatoid arthritis or rheumatic arthritis may impair venous return in the lower limbs, leading to foot swelling.

5. Kidney problems: Kidney diseases such as nephritis or renal failure can affect the body's water and electrolyte balance, potentially causing generalized or localized edema.

6. Lymphatic system issues: Blockage of lymphatic vessels or abnormalities in lymph nodes affecting normal lymphatic drainage can also lead to localized swelling.

7. Medication side effects: Certain medications, such as calcium channel blockers used to treat hypertension, may cause ankle swelling.

8. Malnutrition: Nutritional deficiencies, such as hypoalbuminemia, can lead to edema in various parts of the body.

If foot swelling persists, it is recommended to seek medical evaluation at a hospital immediately.