Bedwetting medicine - desmopressin

What is desmopressin?

Desmopressin is the most popular medicine used to treat bedwetting. Before it is considered, reasons for the bedwetting, and advice or other measures are usually discussed by a medical professional. For more advice about bedwetting see the separate leaflet.

This leaflet only discusses desmopressin.

Desmopressin comes in two tablet forms:

• A tablet which is swallowed.

• A melt tablet which is put under the tongue to dissolve and go straight into the bloodstream.

The advantage of the melt form is that it is not affected by food in the stomach.

How does desmopressin work?

Desmopressin works by reducing the amount of wee (urine) produced in the body at night by the kidneys. This means that the bladder then fills with less urine during the night.

Desmopressin is usually taken at bedtime. Your child should only have sips of fluid from one hour before taking desmopressin until eight hours afterwards, to a total volume of one regular glass of water over that time.

How effective is desmopressin?

Desmopressin works in about 7 in 10 cases.

Most children who take desmopressin will have an improvement. This may be fewer wet nights than usual or passing less urine overnight. It tends to work only when it is taken, so when desmopressin is stopped, the bedwetting comes back. This is why it is mostly used for short periods of time, such as for sleepovers or trips. However, it can be an option for longer-term treatment.

Alternative medicines are sometimes used if desmopressin is not effective. These are usually prescribed by specialist doctors rather than by your GP.

What are the advantages of desmopressin?

Because of the way it works (reducing the amount of urine being made), it has an immediate effect on the first night of treatment. This can be very encouraging to the child.

If it has had no effect after a few days, it is unlikely to work at all. However, sometimes the initial dose is not high enough. A doctor may advise that the dose be increased if it does not work at first.

Food can affect the absorption of desmopressin tablets into the body. Therefore, if it has not worked then try giving the dose at least an hour and a half after the child last ate anything. Also, don't give food to your child just before bedtime. Alternatively, you could try the melt (under the tongue) preparation.

What are the disadvantages of desmopressin?

It does not work in all cases. Also, in children where it has worked, bedwetting usually happens again when desmopressin is stopped. Permanent stopping of bedwetting is more likely with bedwetting alarms than with desmopressin.

The child needs to limit their drinking for an hour before and eight hours after taking the desmopressin. This can be challenging for some children.

Children should not take anti-inflammatory medicines whilst they are taking desmopressin. This includes ibuprofen.

When and how is desmopressin used?

Desmopressin is most commonly used if other measures have not worked or are not considered appropriate by a medical professional. It is recommended as a first option for children who require a rapid response or short-term control of bedwetting (for example, for sleepovers or school trips). Desmopressin is used because it has a faster response rate than using an alarm. If it is used for short-term control, it is usually recommended to take it daily from around a week before the occasion for which it is needed. This gives time to assess how effective it is.

Desmopressin is generally used only in children aged over 7 years; however, sometimes it is used in children a year or two younger. It is not used in children under the age of 5 years. Some children have desmopressin in addition to using an alarm.

If it works, it can be continued for a while. If there has been a response after four weeks then it is usually given for a total of three months. It is then stopped for a week to assess the effect and to see if it is still needed. If there is only a partial response, the dose may be increased. It should then be continued for another six months. If there is no response after four weeks then the treatment is usually stopped.

Are there any side-effects with desmopressin?

Side-effects are rare. Possible side-effects include headaches, feeling sick and mild tummy pain. These go away if the treatment is stopped.

The most serious possible side-effect is due to the way the medicine works - it reduces the amount of urine that is made. Very rarely, this can lead to fluid overload (too much fluid in the body). This may lead to convulsions and serious problems. It has to be stressed that this is extremely rare. However, to reduce the risk of this, when your child takes desmopressin:

• They should not drink too much in the evening. Normal amounts to ease thirst are fine, but not extra drinks for pleasure.

• Your child should only have sips of fluid from one hour before taking desmopressin until eight hours afterwards, to a total volume of one regular glass of water (approximately 240ml) over that time.

Do not give desmopressin to a child who has diarrhoea or is being sick (vomiting) until the illness has passed and your child is well.

Further information about bedwetting can be found in detail on the ERIC website. This is the UK Bladder and Bowel charity for children. Please see the link below under "Further Reading".