At some points we see couples, presumably after sex, in bed together.

At least four points, couples sensually grasp and straddle each other in bed. The most explicit scene of sex (no totally graphic) was in a single episode in Season 4.

Women are occasionally shown in their underwear.

There is some kissing as well.

The plot of the second episode is about impregnating and killing women.

In one episode, people's heads explode. Blood splatters everywhere. A body is briefly seen bloody and headless.

Some fistfights occur.

Martial-arts fighting between two FBI agents in one episode.

Some episodes contain shootouts with some blood.

A giant spiky slug slithers out of a dead man's mouth. This is not graphic, but it is gross and scary.

People sometimes go through scary monster transformations in some episodes, which can be disturbing.

In one episode, the life source (a small metal circle) is cut from shapeshifters' bodies. However, it is not difficult to watch because the shapeshifters' blood is in fact mercury, and they are minor 'bad guys'.

Autopsies are shown onscreen in some episodes, with blood and some gore. Nothing worse than CSI.

In the Pilot episode, skin melts off of people's faces in a brief 20-second scene.

In one episode, a man gets his arm caught in a machine and it is completely mangled and almost sliced in half, but it is brief and the camera does not linger. We see blood splatter on the ground.

In one episode, people randomly break out in viral tumors. This can be hard to watch, because there are many and it can be found gross.

In one of the episodes, a man gets stuck in wall during a bank robbery (he is dead). The main characters saw off the man's hand and place it on a tray (all we see is some blood spraying onto the tray as we hear the saw running). We also see the man's bloody severed hand, but it is unrealistic and almost cheesy.

Most of the cases ocurred during the first three seasons, and repeated in Season 5, used nematode worms, radioactive isotopes, the hallucinogenic drug that simulates deadly butterflies and a skin-growth toxin. In an episode they're used some of their for a massacre.

"God damn" used once.

Infrequent language includes damn, b-tch, ass, S.O.B, and hell.

Some characters were experimented on as children with an extreme, experimental drug.

In two episodes, we see what the characters are seeing when they take drugs, which are LSD and 'Black Blotter'. In this situation, the drugs are actually used for good. In an episode we can see hallucinatory effects of black blotter.

Some of the episodes can be frightening and induce nightmares, but rarely.

Very dark scenes, involving CSI-type crime investigation. Disturbing images, sometimes bloody.

A religious man abducts children, and sucks their spinal fluid through a machine to give The Candyman youth, which is how he stays young. Due to the fluid intake, he also secretes sugar through his sweat.