Water blisters — fluid-filled sacs on your skin — are relatively common.

Referred to as vesicles (small blisters) and bullae (larger blisters), blisters are often simple to treat. It can also be comparatively uncomplicated to identify the cause of a water blister.

When the outer layer of your skin is damaged, your body sends blood to heal and cool the injured area.

Part of that process is the formation of protective pads comprised of blood serum (without the clotting agents and blood cells). These serum pads are water blisters.

Some common reasons water blisters occur are:

Blisters will usually heal on their own with the skin over the blister helping to keep out infection while new skin is formed underneath and the fluid is absorbed.

To keep a blister clean and to protect it from friction, you can cover it with a bandage.

Contact your doctor if:

  • the blister shows signs of infection such as pus, or the area around the blister becomes swollen, red, warm, or painful
  • you develop a fever
  • you have several blisters and you can’t identify what’s causing them
  • you continue to see drainage after you’ve drained the blister
  • you have poor circulation or diabetes

If your blister is large, painful, or likely to be aggravated and pop on its own, you might consider draining it.

To properly drain the fluid while leaving the top skin in place for shielding, there are specific steps you should take. These include:

  1. Wash the blister, the area around it, and your hands with warm water and soap.
  2. Use an absorbent pad to apply iodine to the blister and surrounding area.
  3. Wipe a sharp needle with rubbing alcohol to sterilize it.
  4. Aiming for spots near the blister’s edge, puncture it a few times with the needle.
  5. Allow the fluid to drain, while leaving the overlying skin in place.
  6. Spread the blister area with petroleum jelly or a similar ointment.
  7. Cover the blister with a non-stick gauze bandage.

Follow-up care

  1. Check for any signs of infection daily.
  2. After a few days, using small, sharp scissors and tweezers — wiped with rubbing alcohol to sterilize — cut away all the dead skin.
  3. Apply more ointment and cover the area with a bandage.

The general rule of blister prevention is to stay away from whatever caused the blister.

It’s overly simple, but it also makes sense: If you got blisters from getting a sunburn, spend less time in the sun (or wear more protective clothing and sunscreen).

For specific body parts, here are a few prevention tips to keep in mind:

Feet

  • Wear shoes that fit properly.
  • Wear moisture-wicking socks.
  • Attach moleskin to the inside of your shoe where it rubs against your foot.
  • Put powder in your socks just prior to putting them on.

Hands

  • Wear gloves.
  • Put powder in your gloves just prior to putting them on.

Body, arms, and legs

  • Avoid wearing clothing that causes chafing.
  • Wear moisture-wicking clothing.
  • Apply petroleum jelly to areas that are rubbed by other body parts or clothing.

Water blisters are common and, if left alone, will typically heal on their own.

If a blister grows, becomes painful, or seems likely to be irritated, you might consider draining it using proper sterilization steps and bandaging the open wound. There are steps you can take to prevent blisters, including shoe, sock, and clothing choices.

If you can’t determine the origin of a blister, blister drainage continues after it’s been drained, or if a blister shows signs of infection, contact your doctor.