The Doc Replies

Our expert answers your medical questions

I have been very tired, a little depressed and quite often forget things. My friend thinks I may be lacking in vitamin B12.

Vitamin B12 is an essential vitamin for life. It does many things but is important for red blood cell formation. Without it you can develop anaemia. Other problems when it is low are tiredness, and a sore mouth.

A lack of B12 can also affect the nerves and lead to depression and memory problems, as well as visual changes and pins and needles.

B12 is found in meat, fish, eggs and milk but not in fruit or veg.

In pernicious anaemia the immune system attacks cells in the stomach and stops B12 from being absorbed properly. Sufferers need to be treated with B12 injections. It can run in families and is linked to thyroid disease.

You could have a vitamin B12 deficiency, but equally these symptoms may be caused by something else, so see your GP.

I have a big lump behind my knee the size of a plum stone. My grandmother said it’s a baker’s cyst. Is this an old wives’ tale?

A baker’s cyst is a swelling behind the knee and most often occurs if there is a pre-existing condition such as osteoarthritis.

It is a cyst filled with synovial fluid, the lubricating fluid in the knee joint.

It can cause pain, swelling and tightness behind the knee but it may not be obvious there is a cyst there.

See a doctor to get a diagnosis. How long does alcohol stay in my blood?

On average, it takes about one hour for your body to break down one unit of alcohol.

However this depends on a range of things such as age, weight, whether you are male or female, metabolism, how much food you have eaten, the type and the strength of alcohol and whether you are taking medication.

I have missed one dose of my antibiotics, what should I do?

In most cases you shouldn’t double the next dose if you’ve missed one. Doing that will increase your risk of side effects.

Take your missed dose as soon as you remember it or, if it’s nearly time for your next dose, skip your missed dose altogether.

Always read the patient info leaflet that comes with your antibiotics.