What is it used for?

• Allergic itchy skin rash (urticaria or nettle rash).
• Itching (pruritis).

Pre-med to cause drowsiness before an anaesthetic in children aged two to seven years.

Alimemazine is licensed for use in children from two years of age and adults. However specialists may also sometimes prescribe this medicine on an unlicensed basis to treat itching or urticaria in children under two years of age.

How does it work?

• Vallergan is derived from a group of medicines called phenothiazines, and is a type of medicine called a sedating antihistamine. It works by preventing the actions of histamine.
• Histamine is a substance produced by the body as part of its defence mechanisms. It is stored in cells called mast cells, in almost all tissues of the body. When the body reacts to a foreign substance (known as an allergen, eg flower pollen), the mast cells stimulated by the allergen release their stores of histamine.
• The released histamine then binds to its receptors (H1 receptors), causing a chain reaction that results in allergic symptoms. It causes an increase in blood flow to the area of the allergy, and the release of other chemicals that add to the allergic response.
• All this results in the symptoms of an allergic reaction. In skin allergies, histamine causes inflammation of the skin and results in an itchy rash, swelling and hives, called nettle rash or urticaria.
• Alimemazine works by blocking histamine H1 receptors. It doesn't prevent the actual release of histamine from mast cells, but prevents it binding to its receptors. This in turn prevents the release of other allergy chemicals and increased blood supply to the area, and provides relief from itching and nettle rash.
• Alimemazine is called a sedating antihistamine because it enters the brain in significant quantities and causes drowsiness. As a result, it can be particularly useful for itching that is worse at night. This is often the case in children, who notice itching less during the day when they are active, but are bothered by it at night when they are still and have nothing else to focus on.
• Alimemazine is also used as a pre-med in children to produce sleepiness before operations. It is given one to two hours before the anaesthetic.

How do I take it?

• The dose of this medicine that your doctor prescribes and how often to take the medicine will vary from person to person. It is important to follow the instructions given by your doctor. These will also be printed on the dispensing label that your pharmacist has put on the packet of medicine.
• Alimemazine is usually prescribed two to three times a day for adults, once or twice a day for elderly people and three to four times a day for children.
• Alimemazine can be taken either with or without food.
• You will need to use an oral syringe to measure a dose of the syrup. Ask your pharmacist for help with this if you are not sure what to do.
• Alimemazine tablets should be swallowed whole with a drink of water.
• You should try to minimise skin contact with the tablets. Handling the tablets frequently may rarely cause skin reactions such as redness, swelling and itching.

Use with caution in

• Elderly people (particularly in very hot or very cold weather).
• People who are constipated.
• People with difficulty passing urine.
• Heart disease.
• People with a low volume of circulating blood (hypovolaemia), eg due to dehydration or high-dose diuretic treatment.
• People with a low level of potassium in their blood (hypokalaemia).
• People with epilepsy.
• Alimemazine syrup contains sucrose. This may need to be taken into account by people with diabetes.

Not to be used in

• Decreased kidney function.
• Decreased liver function.
• Epilepsy.
• Parkinson's disease.
• Underactive thyroid gland (hypothyroidism).
• Tumour of the adrenal gland (phaeochromocytoma).
• Abnormal muscle weakness (myasthenia gravis).
• Enlarged prostate gland (prostatic hypertrophy).
• History of closed angle glaucoma.
• Breastfeeding.
• Allergy to phenothiazine medicines, eg chlorpromazine, prochlorperazine.
• Alimemazine tablets contain lactose and may not be suitable for people with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption.

This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

• This medicine is not recommended for use in pregnancy unless considered essential by your doctor. Seek medical advice from your doctor.
• This medicine passes into breast milk. The manufacturer states that mothers who need to take this medicine should not breastfeed during treatment. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

• Drowsiness.
• Nasal congestion.
• Dry mouth.
• Difficulty sleeping.
• Agitation.
• Restlessness.
• Low blood pressure (hypotension).
• A drop in blood pressure that occurs when going from lying down to sitting or standing, which results in dizziness and lightheadedness (postural hypotension).
• Abnormal reaction of the skin to light, usually a rash (photosensitivity).
• Abnormal heartbeats (arrhythmias).
• High blood prolactin (milk producing hormone) level (hyperprolactinaemia). Sometimes this can lead to symptoms such as breast enlargement, production of milk and stopping of menstrual periods.
• Impotence.
• Abnormal movements of the hands, legs, face, neck and tongue, eg tremor, twitching, rigidity.
• Yellowing of the skin and eyes (jaundice).
• Slow, shallow breathing (respiratory depression).
• Decreased numbers of white blood cells in the blood.
• Rhythmical involuntary movement of the tongue, face, mouth and jaw, which may sometimes be accompanied by involuntary movements of the arms and legs (tardive dyskinesia).
• High temperature combined with falling levels of consciousness, paleness, sweating and a fast heart beat (neuroleptic malignant syndrome). Requires stopping the medicine and immediate medical treatment.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.

There may be an increased risk of drowsiness and sedation if this medicine is taken with any of the following (which can also cause drowsiness):

• alcohol
• antipsychotics, eg haloperidol, chlorpromazine
• barbiturates, eg phenobarbital, amobarbital
• benzodiazepines, eg diazepam, temazepam
• monoamine oxidase inhibitor antidepressants (MAOIs), eg phenelzine, tranylcypromine, isocarboxazid, moclobemide
• other sedating antihistamines, eg chlorphenamine, hydroxyzine
• sleeping tablets, eg zopiclone
• strong opioid painkillers, eg morphine, codeine, tramadol
• tricyclic antidepressants, eg amitriptyline.

There may be an increased risk of side effects such as dry mouth, blurred vision, urine retention and constipation if alimemazine is taken with anticholinergic medicines that can cause these types of side effects, such as the following:

• anticholinergic medicines for Parkinson's symptoms, eg procyclidine, orphenadrine, trihexiphenidyl
• anticholinergic medicines for urinary incontinence, eg tolterodine, oxybutynin
• antipsychotics, eg chlorpromazine, clozapine
• antispasmodics, eg hyoscine, atropine
• MAOI antidepressants, eg phenelzine, moclobemide
• tricyclic antidepressants, eg amitriptyline, imipramine.

This medicine may enhance the blood pressure lowering effect of medicines used to treat high blood pressure (antihypertensives), in particular alpha-blocker medicines such as prazosin. (NB alpha blockers are also used to treat the symptoms of an enlarged prostate gland). If you are taking medicines for high blood pressure tell your doctor if you feel faint or dizzy after starting treatment with this medicine, as your doses may need adjusting.

Antihistamines may oppose the effect of histamine (used to treat leukaemia) and are not recommended for people having this treatment.

Antihistamines may also oppose the effect of betahistine (used to treat Ménière's disease).

References:

https://www.drugs.com/uk/vallergan-10mg-film-coated-tablets-leaflet.html

http://www.mydr.com.au/medicines/cmis/vallergan

http://www.netdoctor.co.uk/medicines/allergy-and-asthma/a7715/alimemazine/