Swollen ankles, sock marks that linger and legs that feel heavier as the day goes on. These are the most common signs of water retention: fluid that builds up in your lower legs when circulation slows down.
Usually harmless, often preventable. This guide covers what causes it, how to recognize it and what actually makes a difference.
What is water retention?
Your body is roughly 60% water. Most of it lives inside your cells and blood vessels. The rest sits in the tissue between them, and normally your veins and lymphatic system keep it moving.
When that flow slows down, fluid starts to collect in the tissue. The result is swelling, usually in the feet, ankles and lower legs. Gravity never takes a day off, and your lower legs are often where it shows first.
The medical name is oedema. Most people simply call it water retention, swollen ankles or heavy legs.
Why it happens
Your calf muscles are often called your body's second heart. Every step helps push blood and fluid back up against gravity. When movement slows down, so does that natural pump.
Common causes
Everyday causes
- Standing or sitting for hours
- Warm weather: blood vessels widen, causing more fluid to collect in the tissue.
- High salt intake: salt binds water. More sodium means more water retention.
- Limited daily movement: without muscle activity, drainage slows.
Hormonal causes
- Menstruation: the week before your period often brings temporary water retention.
- Pregnancy: the uterus presses on major veins and hormones hold extra fluid. Swollen feet and ankles are common, especially during the third trimester.
Medical causes
- Varicose veins or venous insufficiency: the valves in your leg veins don't close properly, so blood and fluid linger.
- Lipoedema and lymphedema: conditions where fatty tissue or lymphatic fluid builds up abnormally.
- Heart, kidney or liver conditions can cause retention anywhere in the body.
- Medication side effects: some blood pressure medications, anti-inflammatories and hormonal treatments can cause fluid retention.
Sudden swelling, one leg thicker than the other, pain, shortness of breath, or swelling that doesn't improve should always be checked by a doctor.
Learn more about oedema, varicose veins and lipoedema and lymphedema. If your legs often feel heavy and tired, read our guide on tired legs.
How to spot it
Common signs include:
- Swelling in the feet, ankles or lower legs that builds throughout the day
- Sock marks or shoe imprints that linger for several minutes
- A dent that remains after pressing your thumb into the skin (pitting oedema)
- Shoes or rings feeling tighter in the evening than in the morning
- Legs that feel heavy, tight or tired
- Swelling that decreases overnight
What actually helps
For everyday water retention, these four strategies make the biggest difference.
1. Move more
Movement is the most natural way to keep fluid moving. Walking, cycling and even short mobility breaks help your calves do their job.
2. Elevate your legs
Fifteen to twenty minutes with your legs above heart level can make a noticeable difference. A simple option is the "legs up the wall" position: lie on your back, rest your legs against a wall and let gravity do some of the work.
3. Hydrate and watch your salt intake
Hydration helps your body regulate fluid balance. Combined with reducing highly processed foods, it can significantly reduce day-to-day swelling.
4. Wear compression
Compression is one of the simplest and most effective tools for managing water retention.
STOX compression socks apply graduated compression, highest around the ankle and gradually decreasing towards the knee. This supports blood circulation and helps prevent fluid from accumulating where gravity naturally pulls it.
Whether you're dealing with swollen ankles, looking for everyday support stockings, or seeking support for oedema, compression works with your body's natural pump. Every step becomes more effective. Less heaviness. Less swelling. More comfort at the end of the day.
When compression makes the biggest difference
Long flights create the perfect conditions for swollen feet and heavy legs. Hours of sitting, reduced movement and cabin pressure all contribute. Compression helps support healthy circulation, making it easier to arrive feeling comfortable and refreshed.
For people who spend all day on their feet, such as nurses, teachers, hospitality staff and hairdressers, compression is one of the smartest upgrades you can make. It supports circulation throughout the day and helps reduce the heavy-leg feeling before it starts.
Pregnancy and warm weather can also increase fluid retention. In both situations, graduated compression provides additional support when your body needs it most. Learn more about support stockings during pregnancy.
When to see a doctor
Seek medical advice if:
- Swelling comes on suddenly
- Only one leg is affected
- Swelling is accompanied by pain, redness or warmth
- You're short of breath or have chest pain
- Swelling does not improve overnight
- You're urinating less or gaining weight rapidly
The short version
Water retention is often your body's way of asking for more movement, better circulation or a little extra support.
Walk more. Elevate your legs. Stay hydrated. And when gravity keeps winning, graduated compression helps put things back in motion.
Because pressure isn't always the problem. Sometimes it's the solution.
Discover our full range of compression socks or learn more about STOX compression technology.
