Haymine sustained-release tablets contain two active ingredients, chlorphenamine (previously spelt chlorpheniramine in the UK) and ephedrine. Chlorphenamine is a type of medicine called a sedating antihistamine and ephedrine is a type of medicine called a decongestant.
Chlorphenamine controls allergies by blocking the action 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 allergic rhinitis (hayfever, pet and dust allergies and so on) histamine causes inflammation of the nose, eyes or airways and results in itchy watery eyes, a runny nose, sneezing and nasal congestion.
Chlorphenamine controls the allergy 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 the typical symptoms of hayfever and other nasal allergies.
Chlorphenamine is called a sedating antihistamine because it enters the brain in significant quantities and causes drowsiness.
Ephedrine works by acting on alpha receptors that are found in the walls of blood vessels in the linings of the nasal passages and sinuses. It causes these blood vessels to contract and narrow, thereby decreasing blood flow into the linings of the nose and sinuses. This reduces the feeling of congestion and also reduces the production of mucus. It relieves a blocked nose caused by the allergic reaction.
Ephedrine also has mild stimulant properties and so may counteract some of the drowsiness caused by the chlorphenamine.
Haymine tablets are sustained-release tablets. They are designed to release the medicine slowly and continuously over a few hours to help provide steady blood levels of the medicine throughout the day. These tablets must be swallowed whole and not broken, chewed or crushed to avoid damaging the sustained-release action.
This medicine should not be used if you are allergic to one or 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.
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.
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.
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.
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.
You should not use other decongestant medicines in combination with this one.
You should not use this medicine if you are currently taking a type of medicine called a monoamine oxidase inhibitor (MAOI), or have taken one of these medicines in the last 14 days. MAOIs include the antidepressants phenelzine, tranylcypromine, isocarboxazid and moclobemide, and the anti-Parkinson's medicines selegiline and rasagiline. This is because the combination of ephedrine with these medicines could cause a dangerous increase in blood pressure (hypertensive crisis).
If ephedrine is taken with any of the following medicines, the combination may cause an increase in blood pressure. If you are already taking any of these medicines you should avoid taking this one as well:
Ephedrine may reduce the effects of medicines to treat high blood pressure (antihypertensives). If you are taking medicines for high blood pressure you should not take this medicine unless your doctor agrees.
There may be an increased risk of drowsiness and sedation if chlorphenamine is taken with any of the following (which can also cause drowsiness):
There may be an increased risk of side effects such as dry mouth, blurred vision, urine retention and constipation if chlorphenamine is taken with anticholinergic medicines that can cause these type of side effects, such as the following:
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).
There are currently no other medicines available in the UK that contain both chlorphenamine and ephedrine as the active ingredients.
Piriton contains just chlorphenamine.