The swollen ‘glands’ that you feel – most commonly on your neck when you have a throat infection – are called lymph glands or lymph node. They are connected by a complicated network of tubes called lymph channels, which run all over your body.
The channels and glands are full of a fluid called lymph, which in turn contains millions of white blood cells. These cells form the basis of your immune system, which helps you to fight off disease.
If your body detects an invader – an infection or another foreign object that it doesn’t recognise – it will mobilise this army of white blood cells. These rush to the spot they’re needed, congregating in the lymph glands closest to where they are needed. Think of your lymph channels as train tracks, the lymph glands as the stations or depots and your white cells as passengers (armed to the teeth to fend off enemies!)
Why do they swell?
Lymph glands are normally about the size of peas. If you’re slim, you may be able to feel even some normal sized glands under your skin. If they fill with white blood cells, they swell and usually become tender. Once the infection has gone they almost always shrink back down to their normal size, although this may take a week or two.
By far the most common reason for swollen glands is an infection. This usually causes swelling the glands nearest the infection. Your network of connecting lymph channels drains the whole of one part of your body. For instance, the lymph glands in your groin are the depot for all the tracks (lymph channels) in your leg, so an infection between your toes can cause swollen glands in your groin on that side.
- Throat infections, like tonsillitis, will cause the glands in your neck to swell.
- Some infections, such as glandular fever, cause all the glands in your body to swell, so you may feel glands in your armpits, groins, and neck.
- Scalp skin conditions or even head lice may cause the lymph glands at the back of the head to swell.
- Skin infections of the arm may cause lymph glands in the armpit to swell.
- Infections of the leg or genitals, or nappy rash, may cause lymph glands in the groin to swell.
- Viral infections such as flu (influenza), chickenpox or glandular fever (infectious mononucleosis) affect the whole body. You may then develop swollen lymph glands in various parts of the body such as the neck, armpit, and groins.
Much less commonly, swollen glands can be caused by cancer. Cancer affecting the blood system (leukaemia) or the lymph system itself (lymphoma) will tend to cause glands in more than one area to swell. On the whole, these lymph nodes aren’t tender, at least at first, and tend to grow in size more slowly than those connected with infection.
If cancer in one part of the body spreads through the lymph system, it can cause swelling of the lymph glands nearby. For instance, breast cancer can cause swollen glands in one armpit, and throat or lung cancer can enlarge the glands in the neck.
Should you worry?
Usually not at all! Having swollen glands is often a sign that your body is already working hard to fight off an infection. However, you should get them checked out if:
- You have swollen glands and you aren’t aware of any infection which could be to blame
- Your glands don’t go back to normal within a couple of weeks of any infection setting
- You have other symptoms such as feeling unduly tired, weight loss, night sweats or persistent fevers