Vertigo
The vestibular apparatus provides constant feedback to the brain about the position of our body. When something disturbs the vestibular apparatus, such as movements of the head when travelling by boat or car, nerve signals are sent from the vestibular apparatus to the vomiting centre. This can cause the symptoms of motion sickness, such as nausea, dizziness or spinning sensations (vertigo) and vomiting.
By blocking the histamine receptors in the vomiting centre, Promethazine Theoclate prevents disturbances in the middle ear from activating the vomiting centre.
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 taking Promethazine Theoclate. Similarly, check with your doctor or pharmacist before taking any new medicines while taking Promethazine Theoclate, to make sure that the combination is safe.
Promethazine Theoclate should not be taken by anyone who has taken a type of antidepressant called a monoamine oxidase inhibitor (MAOI), eg phenelzine, tranylcypromine, isocarboxazid, in the previous 14 days.
You are more likely to feel drowsy if you take Promethazine Theoclate with any of the following (which can also cause drowsiness):
- alcohol
- antipsychotic medicines, eg chlorpromazine
- barbiturates, eg phenobarbital
- benzodiazepines, eg diazepam, temazepam
- sedating antihistamines, eg chlorphenamine, brompheniramine, hydroxyzine
- sleeping tablets, eg zopiclone
- strong opioid painkillers, eg morphine, codeine, dihydrocodeine, tramadol
- tricyclic antidepressants, eg amitriptyline.
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 promethazine. Just because a side effect is stated here does not mean that all people using Promethazine Theoclate will experience that or any side effect.
- Drowsiness or feeling tired.
- Dizziness.
- Restlessness.
- Headache.
- Nightmares.
- Blurred vision.
- Difficulty passing urine.
- Dry mouth.
- Confusion.
- Feeling disorientated.
- Unexpected increase in excitability in children.
- Increased sensitivity of the skin to sunlight (photosensitivity). If affected you should avoid sun lamps and direct sunlight while you are taking this medicine.
- Loss of appetite.
- Awareness of your heartbeat (palpitations).
- Abnormal heartbeats (arrhythmias).
- Low blood pressure (hypotension).
- Abnormal movements of the hands, legs, face, neck and tongue, eg tremor, twitching, rigidity (extrapyramidal effects).
- Blood disorders.
Small amounts of Promethazine Theoclate may pass into breast milk. This is not expected to be harmful to a nursing infant with occasional short-term use of Promethazine Theoclate, but there is a risk that it may cause drowsiness, irritability or excitement in a newborn baby. If you are breastfeeding you should not take Promethazine Theoclate without getting medical advice from your doctor first.
Avoid drinking alcohol while taking Promethazine Theoclate because this is likely to make the above effects more likely or worse.
Promethazine Theoclate tablets may make your skin more sensitive to sunlight than usual, so you should avoid exposing your skin to direct sunlight or sunlamps until you know how your skin reacts. If you can’t avoid strong sunlight you should use a sunscreen lotion or make sure your skin is protected with clothing.
This medicine may interfere with some pregnancy tests, causing false negative or false positive results.
If you are due to have any skin prick tests to diagnose allergies you should stop taking Promethazine Theoclate at least 72 hours before the tests. This is because antihistamines can prevent or lessen the skin reactions that indicate an allergy, and so can make the test results unreliable.