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Dehistine (Generic Phenylephrine)

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Why is this medication prescribed?

Dehistine, which contains Chlorpheniramine, Methscopolamine, and Phenylephrine, is primarily prescribed to relieve symptoms associated with seasonal allergies, such as sneezing, runny or stuffy nose, itching, and watery eyes. It works by blocking the action of histamine, a substance produced by the body during an allergic reaction. Methscopolamine helps to reduce nasal secretions, while Phenylephrine constricts blood vessels in the nasal passages, thereby relieving nasal congestion.

How should this medicine be used?

Dehistine should be used exactly as directed by your healthcare provider or as indicated on the medication label. Follow these general guidelines:

  • Dosage: Take the medication exactly as prescribed by your doctor. The dosage may vary based on factors such as age, medical condition, and response to treatment.
  • Administration: Dehistine is typically taken orally, either with or without food. Swallow the tablets whole with a full glass of water. Do not crush, chew, or break the tablets unless instructed otherwise by your doctor or pharmacist.
  • Timing: Take Dehistine at the same times each day to maintain a consistent level of the medication in your bloodstream and to maximize its effectiveness.
  • Do not exceed recommended dose: Take only the prescribed amount of Dehistine. Do not take more of it or take it more frequently than directed by your doctor. Taking too much can lead to overdose or increase the risk of side effects.
  • Duration of use: Use Dehistine for the duration recommended by your healthcare provider, even if your symptoms improve. Stopping the medication prematurely may allow the symptoms to return or worsen.
  • Consult your doctor: If you have any questions or concerns about how to use Dehistine, including its dosage, administration, or potential side effects, consult your doctor or pharmacist for guidance.

Always read the medication label and accompanying patient information leaflet for specific instructions provided by the manufacturer. If you experience any adverse reactions while taking Dehistine, contact your healthcare provider immediately.

Other uses for this medicine

Dehistine, containing Chlorpheniramine, Methscopolamine, and Phenylephrine, is primarily prescribed for allergy relief. However, it may also be used for other conditions as determined by your healthcare provider. Some off-label uses may include treating symptoms such as nasal congestion, sinus pressure, and cough associated with the common cold.

What special precautions should I follow?

When using Dehistine, it’s essential to follow special precautions to ensure safe and effective use. Here are some precautions to keep in mind:

  • Medical history: Before taking Dehistine, inform your doctor about your complete medical history, especially if you have any pre-existing conditions such as heart disease, high blood pressure, thyroid disorders, glaucoma, urinary problems, stomach or intestinal problems, or difficulty urinating due to an enlarged prostate gland.
  • Allergies: Inform your doctor if you have any allergies to Chlorpheniramine, Methscopolamine, Phenylephrine, or any other medications.
  • Pregnancy and breastfeeding: If you are pregnant or breastfeeding, consult your doctor before using Dehistine. It’s essential to weigh the potential risks and benefits under the guidance of your healthcare provider.
  • Interactions: Inform your doctor about all the medications you are currently taking, including prescription drugs, over-the-counter medications, vitamins, and herbal supplements. Some medications may interact with Dehistine, potentially increasing the risk of side effects or reducing its effectiveness.
  • Driving and operating machinery: Dehistine may cause dizziness or drowsiness, especially at the beginning of treatment. Avoid driving, operating machinery, or engaging in activities that require mental alertness until you know how this medication affects you.
  • Alcohol: Avoid consuming alcohol while taking Dehistine, as it may exacerbate the drowsiness and dizziness caused by the medication.
  • Overdose: Taking more than the recommended dose of Dehistine can lead to overdose, which may cause serious symptoms such as confusion, hallucinations, rapid heartbeat, seizures, or difficulty breathing. Seek immediate medical attention if you suspect an overdose.
  • Storage: Store Dehistine at room temperature away from moisture and heat. Keep it out of reach of children and pets.

Always follow your doctor’s instructions and read the medication label carefully for specific precautions and warnings provided by the manufacturer. If you have any concerns or questions about using Dehistine, consult your healthcare provider for personalized advice.

What special dietary instructions should I follow?

There are no specific dietary instructions associated with Dehistine. However, it’s important to maintain a healthy diet and stay hydrated while taking the medication. Avoid consuming excessive amounts of alcohol, as it may worsen certain side effects such as dizziness or drowsiness.

What should I do if I forget a dose?

If you miss a dose of Dehistine, take it as soon as you remember. However, if it’s almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take extra medication to make up for the missed dose. Taking too much Dehistine can increase the risk of side effects. If you’re unsure about what to do, consult your doctor or pharmacist for advice.

What side effects can this medication cause?

Dehistine, like any medication, may cause side effects in some individuals. Common side effects associated with Dehistine include:

  • Drowsiness: This is one of the most common side effects of Dehistine. It may impair your ability to perform tasks requiring mental alertness, such as driving or operating machinery.
  • Dizziness: Some people may experience feelings of lightheadedness or vertigo while taking Dehistine.
  • Dry mouth: Dehistine can cause a dry sensation in the mouth due to its anticholinergic properties.
  • Blurred vision: Vision may become blurry or unclear while taking Dehistine.
  • Constipation: Dehistine may lead to difficulty passing stools or infrequent bowel movements in some individuals.
  • Difficulty urinating: Some people may experience trouble urinating or incomplete emptying of the bladder while taking Dehistine, especially in men with prostate enlargement.
  • Nausea or stomach upset: Dehistine may cause gastrointestinal discomfort, including nausea or upset stomach.
  • Headache: Headaches are a possible side effect of Dehistine, although they are less common.
  • Nervousness or restlessness: Some individuals may feel jittery or anxious while taking Dehistine.
  • Insomnia: Difficulty falling asleep or staying asleep may occur in some people as a side effect of Dehistine, particularly if the medication is taken close to bedtime.
  • Increased heart rate or palpitations: Dehistine may cause a rapid heartbeat or sensations of palpitations in some individuals.
  • Sweating: Excessive sweating or perspiration may occur as a side effect of Dehistine.

These side effects are not exhaustive, and individual responses to medication can vary. Some people may experience none of these side effects, while others may experience several. If you experience any severe or persistent side effects while taking Dehistine, or if you have concerns about your symptoms, it’s important to contact your healthcare provider for further evaluation and guidance.

What should I know about storage and disposal of this medication?

When it comes to storage and disposal of Decon G:


  • Store Dehistine at room temperature away from moisture, heat, and direct light.
  • Keep the medication out of reach of children and pets to prevent accidental ingestion.
  • Do not store Dehistine in the bathroom, as the moisture and humidity can degrade the medication.
  • Keep Dehistine in its original packaging or container to ensure proper identification and to protect it from environmental factors.


  • Dispose of any unused or expired Dehistine properly according to local regulations or guidelines.
  • Do not flush Dehistine down the toilet or pour it down the drain unless instructed to do so by your pharmacist or local waste disposal authority.
  • Consult your pharmacist or healthcare provider for information on the safe disposal of Dehistine. They may have specific instructions or programs available for medication disposal in your area.

In case of emergency/overdose

  • In case of an emergency or overdose, call your local emergency services or poison control center immediately. You can also seek urgent medical attention by going to the nearest emergency room.
  • Be prepared to provide information about the amount of Dehistine ingested, the time of ingestion, and any symptoms experienced.
  • Do not attempt to treat an overdose of Dehistine on your own without medical guidance. Overdose symptoms may include confusion, hallucinations, rapid heartbeat, seizures, difficulty breathing, or loss of consciousness.

What other information should I know?

  • Keep all appointments with your doctor and laboratory. Your doctor may need to monitor your response to Dehistine and adjust your treatment plan accordingly.
  • Do not share Dehistine with others, even if they have similar symptoms. This medication is prescribed specifically for you based on your medical condition and needs.
  • Inform any healthcare provider who treats you about all the medications you are taking, including Dehistine, to avoid potential drug interactions.
  • Follow your doctor’s instructions carefully regarding dosage, administration, and any other special instructions provided.
  • If you have any questions or concerns about Dehistine or its use, do not hesitate to consult your healthcare provider or pharmacist for guidance.

By following these guidelines for storage, disposal, handling emergencies, and other important information, you can use Dehistine safely and effectively.

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