Always take Nexium as instructed by your doctor and read the leaflet before taking Nexium. They can be taken at any time of the day either with food or on an empty stomach. They should be swallowed whole with a drink of water and not chewed or crushed.  If you are taking this medicine over a long time period (especially over a year) your doctor will monitor you. 

If you forget to take a dose at the correct time, take it as soon as you remember it.  However, if it is nearly time for your next dose, skip the missed dose and do not take a double dose at the same time.

If you take more tablets than prescribed, talk to your doctor or pharmacist straight away.

The active substance in Nexium is 20mg esomeprazole (as magnesium trihydrate). Other ingredients are glycerol monostearate 40-55, hyprolose, hypromellose, iron oxide (reddish-brown, yellow) (E172) magnesium stearate, methacrylic acid ethyl acrylate copolymer (1:1) dispersion 30 per cent, microcrystalline cellulose, synthetic paraffin, macrogol, polysorbate 80, crospovidone, sodium stearyl fumarate, sugar spheres (sucrose and maize starch), talc, titanium dioxide (E171), triethyl citrate.

Nexium 20mg should not be taken if you are allergic to esomeprazole or any other ingredients within these tablets such as other proton pump inhibitor medicines. Do not take Nexium if you are taking medicine containing nelfinavir, have severe liver or kidney problems and if you are not sure, check with your doctor or pharmacist first. Nexium could hide the symptoms of other diseases so check with your doctor if you lose a lot of weight for no reason and have problems swallowing, stomach pain or indigestion, vomiting food or blood, passing black stools. Taking medication like Nexium for a period of more than one year may increase your risk of facture in the hip, wrist or spine. Tell your doctor if you have osteoporosis or are taking corticosteroids or are taking any other medicines including those without a prescription.
Nexium may have some side effects which not everyone will get but if you notice any of these, you must contact your doctor straight away. Sudden wheezing, swelling of lips, tongue, throat or body, difficulty swallowing (severe allergic reaction) rash, fainting. Reddening of the skin with blisters or peeling, severe blisters and bleeding in the lips, eyes, mouth, nose and genitals which could be ‘Stevens-Johnson syndrome’ or ‘toxic epidermal necrolysis’. Yellow skin, dark urine and tiredness which can be symptoms of liver problems.
Other side effects could be headache, diarrhoea, stomach pain, constipation, wind (flatulence), nausea or vomiting. Possible swelling of the feet and ankles, disturbed sleep, dizziness, tingling feels such as ‘pins and needles’, feeling sleepy, spinning feeling, dry mouth. Changes in blood tests that check how the liver is working, skin rash, lumpy rash and itchy skin, fracture of the hip, wrist or spine (if Nexium is used for a long period and in high doses). 
Rarely, side effects such as reduced number of white cells or platelets in the blood which cause weakness, bruising or make infections likely, may be seen. Low levels of sodium in the blood may cause weakness, vomiting and cramps. The feeling of agitation, confusion or depression, taste changes, blurred vision, sudden feelings of wheezy breathing or shortness of breath, inflammation of the inside of the mouth, thrush, liver problems including jaundice which can cause yellow skin, dark urine and tiredness. Hair loss, skin rash on exposure to sunshine, joint pains or muscle pains, generally feeling unwell and lacking energy, increased sweating. 
Possible but very rare side effects of Nexium could be lack of white blood cells, aggression, seeing, feeling or hearing things that are not there, severe liver problems leading to liver failure and inflammation of the brain. Sudden onset of a severe rash or blistering or peeling skin which may be associated with a high fever and joint pains, muscle weakness, severe kidney problems or enlarged breasts in men.
If you are on Nexium for more than three months it’s possible that the magnesium levels in the blood may fall. This can be seen as fatigue, involuntary muscle contractions, disorientation, convulsions, dizziness or increased heart rate. Low magnesium levels can lead to reduced potassium or calcium levels and your doctor may perform regular blood tests to monitor your levels.  Inflammation in the gut which leads to diarrhoea. In very rare cases Nexium may affect the white blood cells leading to immune deficiency which may show with symptoms such as fever with severely reduced general condition or with symptoms of local infection such as pain in the neck, throat or mouth or difficulties in urinating, you must consult your doctor as soon as possible. It is important to give information about your medication at this time.