What kind of Anthurium is it, Loopy?

I'll assume its the common type, Anthurium andreanum, now sold in most supermarkets. First, check the stems and base and underside of the leaves for any signs of insect infestation or any other signs of disease. Assuming you don't find anything, check the conditions you're keeping it in - the following is what this plant requires:

Brightly lit spot, out of sun in summer, winter sun tolerated. Average warmth, but a minimum of 60 deg F in winter, out of draughts. Keep compost moist, but not sodden, at all times, do not allow to dry out, so water a little every few days (unlike most other houseplants)or as necessary. Mist with water frequently, or stand on a pebble tray half filled with water kept topped up, this plant hates dry air. Flowering is spring to autumn - feed with a general purpose houseplant food during active growing season. Repot every couple of years in spring, split the plant at the same time.
If the leaves on your plant are dusty, clean them with a soft brush or cloth, and if that doesn't remove it, dip a soft cloth in a little milk and clean gently.

Hi Tugbrethil - I am not sure what type it is. I did have a label for it, but it seems to have disappeared! It has red flowers, and large green leaves (but I assume that's not helpful in determining what type it is!)

Thanks Bamboo - I currently have it near double patio doors so it gets day light and but it's not in a draught. I have a feeling the problem is that the air is dry because we've had the heating on a lot. I have, over the last few days, been misting the leaves with water, but it just looks so sad and I really don't want to lose it. Some of the leaves are soft and don't feel waxy. Most of the leaves are droopy and limp. It was doing really well and all of a sudden it's looking very unwell.

Thanks for the advice.

Suggest you check the plant, and the compost its in, thoroughly for signs of infestation or disease - my year old anthurium is sitting on the floor near my balcony door, with a central heating pipe running behind it, very close - I got round that by leaving a small pot with water in behind the plant, between it and the hot pipe, to increase humidity round the plant. Blooming thing's driving me bonkers, it's absolutely huge and I can't wait till Spring to split it into 3 pieces... not many red spathes though, at the moment. So the heating might be contributing to its problems, or it might not be that at all.

Bamboo probably has most of the answers, Loopy. Other things to check:

When it was repotted, was it planted lower than it was in the original pot? That is, does it now have compost piled up around the lower stems? Ideally, the lowermost roots should just barely be exposed. Planting it too deep causes the lower stem to rot, keeping water from getting to the leaves.

Does the pot have drainage? If so, is it sitting in a decorative pot without a drainage hole, or a saucer that always seems full of water? Keeping the lower layers of soil saturated all the time is a sure way to start root rot. Ideally, take the pot to the sink or bathtub to water, and only return to its home when it's fully drained. Alternatively, use a bulb baster to suck the saucer dry shortly after watering.

Was it upgraded to a much larger pot? Too much unused compost can also cause root rot. Ideally, don't bump the pot size up more than 25%--i.e., if it's coming out of a 20 cm pot, don't go bigger than a 25 cm size.

What kind of potting compost is it? Although Anthuriums need constant moisture, their roots also need a lot of oxygen. Much better to use a fast-draining compost and water more often, than to smother the roots in a brand that has too much peat and/or loam.

Hope all theis helps!