Fallout Shelter is nothing short of a phenomenon at this point. At the time of this writing, it has only been out for a week — and everybody is playing it. Some of our better players have shared tips on how to get more dwellers and how to earn more caps, but it takes a special breed of Overseer to answer the one question on a lot of new players minds — specifically, one who has caused more damage and havoc to his denizens than any other mayor.

Why is my vault dweller’s heath red?

Radiation

fallout shelter red health radiation

When you take radiation damage (more often than not from rad roaches, though a lack of water can cause this too), your health meter will reflect this by adding a section of red. The more damage you take, the more red will appear in a dweller’s health bar. The result? Your health can only be filled in the sections that aren’t red.

In other words, radiation restricts how much health your dweller can have. The maximum health is lowered by radiation damage. DON’T PANIC — something can be done.

Radaways

falloutshelterradaway

The most immediate way to resolve your dweller’s red health woes is by using Radaways. Think of these as reverse health packs. They don’t actually heal your dweller, but they do cure radiation, allowing your dweller to return to full health through other means.

To use a Radaway, click on your dweller and then select the radaway icon from the menu. It looks like a little I.V. bag with a radiation warning on it.

You can get Radaways as a random drop by purchasing a lunchbox, but that’s a solution both silly and costly. Instead, build a Science Lab and assign a high intelligence dweller to it. the Science Lab will unlock once your vault has 16 dwellers.

Water

falloutshelterwater

Fallout Shelter has three main resources you need to worry about: Energy, Food and Water. Each of these relate to a specific reality your player needs to deal with. Energy powers your rooms, food slowly replenishes your health, and water counters radiation damage.

There’s a catch, though. This is a slow process. And if you close the game, it doesn’t keep chugging away in the background like so many mobile games do. You’ll need to make sure you have plenty of water stored up (keep your resources in the green) for the radiation damage to see some reduction. Lucky for you, Fallout Shelter is a great game to keep open on your desk as you’re doing other things.

Even beyond radiation healing, keeping the game open seems to be the best way to make significant progress in a short period of time, so don’t close Fallout Shelter just yet. Your dwellers will thank you for it.