Thonzylamine is an antihistamine and works by reducing the symptoms brought by the natural substance histamine to our body such as watery eyes, runny nose and sneezing. Phenylepherine is a decongestant that relieves nasal congestion by shrinking the blood vessels in the nasal passages.

This combination medication is used to treat symptoms caused by the common cold, flu, allergies, or other breathing illnesses (such as sinusitis, bronchitis), temporarily. This medication may also be used in other conditions to be determined by your doctor.

Do not use this drug:

  • To children under 6 years unless specifically prescribed by the doctor
  • If you are allergic to any ingredient in Thonzylamine and Phenylephrine
  • If you have severe high blood pressure, severe heart blood vessel disease, rapid heartbeat, or severe heart problems
  • If you take Sodium Oxybate (GHB) or if you have taken Furazolidone or a Monoamine Oxidase Inhibitor (MAOI) (eg, Phenelzine) within the last 14 days

Common side effects may include:

  • Drowsiness
  • Dizziness
  • Dry Mouth, Nose or Throat
  • Headache
  • Upset Stomach
  • Constipation
  • Trouble Sleeping

Notify your doctor promptly if any of these symptoms persist or worsen.

Your doctor may have prescribed this medication because he or she judged that the benefit to you is greater than the risk of side effects.

Rare serious side effects may include:

  • Mental or Mood Changes (such as Confusion, Hallucinations)
  • Ringing in the Ears
  • Difficulty Urinating
  • Vision Changes (such as Blurred or Double Vision)
  • Fast or Irregular Heartbeat
  • Seizure
  • Severe Allergic Reaction

Seek immediate medical attention if you experience any of these serious side effects.


Before taking this product, tell your doctor or pharmacist:

  • If you are allergic to any of its ingredients; or if you have any other allergies.
  • If you are pregnant or breastfeeding.
  • If you are to undergo any surgery.
  • Your medical history, especially of:
    • Breathing Problems (such as Asthma, Emphysema)
    • Diabetes
    • Glaucoma
    • Heart Problems
    • High Blood Pressure
    • Kidney Problems
    • Liver Disease
    • Seizures
    • Stomach or Intestinal Problems (such as Ulcers, Blockage)
    • Overactive Thyroid (Hyperthyroidism)
    • Difficulty Urinating (such as Due to Enlarged Prostate)

This drug may cause dizziness, drowsiness or blurred vision. Avoid activities requiring alertness or clear vision such as driving until you are sure you can perform such activities safely. Limit the use of alcohol and certain other medications that cause drowsiness.

Older adults and children may be more sensitive to the side effects of this drug, especially dizziness, drowsiness, mental or mood changes, constipation, fast heartbeat, trouble urinating, or blood pressure changes.



Drug interactions may either lessen the effectiveness of this drug or heighten the risk for severe side effects. It’s important to inform your doctor all the medication including prescription and non-prescription and herbal medicines you are taking or going to take.

Possible interactions with this drug are:

  • Antihistamines Applied to the Skin (such as Diphenhydramine Cream, Ointment, Spray)
  • Blood Pressure Medications (Especially Reserpine, Guanethidine, Methyldopa, Beta Blockers such as Atenolol, or Calcium Channel Blockers such as Nifedipine)
  • MAO Inhibitors (Isocarboxazid, Linezolid, Methylene Blue, Moclobemide, Phenelzine, Procarbazine, Rasagiline, Selegiline, Tranylcypromine)
  • Opioid Pain or Cough Relievers (such as Codeine, Hydrocodone)
  • Alcohol
  • Drugs for Sleep or Anxiety (such as Alprazolam, Lorazepam, Zolpidem)
  • Muscle Relaxants (such as Carisoprodol, Cyclobenzaprine)
  • Other Antihistamines (such as Cetirizine, Diphenhydramine)

This medication may interfere with certain medical or laboratory tests such as brain scan for Parkinson’s disease. Make sure laboratory personnel and all your doctors know you use this drug to avoid false results.

Call emergency hotline if someone has overdosed and has serious symptoms such as passing out or trouble breathing.

Symptoms of overdose may include:

  • Irregular Heartbeat
  • Hallucinations
  • Fainting
  • Seizures


Available brand/s:

  • Dimerrin
  • Disudrin
  • Loraped
  • Mydfrin

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