Dayhist-D – Information, Uses, Side Effects and Dosage

clemastine, phenylpropanolamine

Drug Trade Name: Dayhist-D, Allerhist-D and Tavist-D

Category: Antihistamine, Decongestant

Generic Name: clemastine, phenylpropanolamine

Introduction and Quick Information about Dayhist-D:


Dayhist-D belongs to a group of medications known as Upper Respiratory Combinations. clemastine, phenylpropanolamine is the generic name of Dayhist-D. Dayhist-D has two more brand names, such as Allerhist-D and Tavist-D.

Clemastine is an antihistamine. It blocks the effects of histamine in the body. Clemastine prevents sneezing; watery eyes or nose; and other symptoms of allergic reactions. Phenylpropanolamine is a decongestant. It constricts the blood vessels. This reduces the blood flow to certain areas and allows breathing passages to open up. Clemastine and phenylpropanolamine together are used to treat nasal congestion and sinusitis associated with allergies.You should inform your medical expert before using Dayhist-D.

Is Dayhist-D Approved by U.S. FDA?

No doubt Dayhist-D is an effective medication for the treatment of sneezing, watery, itchy nose & eyes, and other signs of hay fever and allergies. However, these drugs are not generally reviewed by U.S. FDA (Food and Drug Administration. Consult your healthcare provider before using Dayhist-D.

Usage and Benefits of Dayhist-D:

This drug inhibits the effects of a chemical known as histamine in your body & it prevents sneezing, watery, itchy nose & eyes and other symptoms of hay fever and allergies.

This medicine constricts blood vessels and thus reduces the blood circulation to certain portions and allows breathing passages to open up. Dayhist-D is also used to treat sinusitis and nasal congestion caused by hay fever and other allergies.You should talk to your medical professional before using Dayhist-D.

Dayhist-D Side Effects:

Do not use Dayhist-D if you have consumed MAOI (monoamine oxidase inhibitor) such as tranylcypromine (Parnate), phenelzine (Nardil), or isocarboxazid (Marplan) in last 14 days. Patients must be aware that they can experience hazardous drug interaction, leading to severe side effects. Before using Dayhist-D, inform your healthcare provider if you have:

  • Liver disease
  • Kidney disease
  • Diabetes
  • Glaucoma
  • High blood pressure or any type of heart disease
  • Thyroid disease
  • An enlarged prostate
  • Difficulty in urinating

Patients might not be recommended to use Dayhist-D, or might require a special monitoring or dosage adjustment during treatment if they have any of these above-listed health issues. You can also experience various unwanted side effects if you do not use this medication properly.

Some side effects of Dayhist-D:

  • Dizziness or drowsiness
  • Dryness of the mouth, nose, and eyes
  • Blurred vision
  • Difficulty in urinating
  • Excitation in children

It is the partial list of side effects but you can notice these while using this medicine. Talk to your medical practitioner about any kind of adverse reaction that seems unusual before your condition becomes bothersome.


General Recommended Dosages of Dayhist-D:

Use Dayhist-D exactly as suggested by your health care provider. If you have any doubt about the directions regarding this medicine, ask your doctor, nurse, or pharmacist to explain all the instructions or directions.

Take each dose of Dayhist-D with a glass of water. Don’t break, chew, or crush the pills. You should swallow them entirely. Avoid taking more than one pill every twelve hours. Taking one pill per day is acceptable. Never use more than 2 pills in one day. Taking excess amount of Dayhist-D can cause severe nervousness, insomnia, and dizziness.

Do not use this medicine for more than 7 days in a row. In case your condition does not improve or gets worse, or if you are suffering from a fever, talk to your health care provider. 

You should store Dayhist-D away from heat and moisture at room temperature conditions.

In case I Miss my Dose?

In case you forget to use your regular dose of Dayhist-D, use it as soon as you can. However, if it’s a time to take your next scheduled dose, you should skip the missed dose and have your usual schedule dose. Never think of using a double dose to compensate for the missed doses otherwise you can experience various unwanted side effects.

Patients should call their medical expert if they forget to take their scheduled dosages of Dayhist-D. Inform your medical expert about missing a dose of Dayhist-D.

In case I Take Overdose?

You should be aware of negative outcomes that may occur in case you have consumed more than recommended dose.

Overdose symptoms of Dayhist-D might include:

  • Large pupils
  • Dry mouth
  • Vomiting
  • Nausea

In case a patient has swallowed an excess amount of this medication then contact your health care provider without any delay. Immediate treatment can provide you relief and prevent any severe outcomes.

Drug Interactions of Dayhist-D:

Some medicines may interact with Dayhist-D. You should tell your doctor if you are using other medications together with Dayhist-D. Interactive drug can cause various severe reactions.

Do not use Dayhist-D if you have consumed MAOI (monoamine oxidase inhibitor) such as tranylcypromine (Parnate), phenelzine (Nardil), or isocarboxazid (Marplan) in last 14 days. Patients may experience risky drug interaction, leading to severe side effects. Before using Dayhist-D, inform your health care provider.

Do not use other over-the-counter cold, cough, diet, allergy, or sleep aids during treatment with Dayhist-D. This medicine might cause side effects along with other medications and result in drowsiness, including alcohol consumption, antidepressants, other antihistamines, anxiety medicines, pain relievers, muscle relaxants, and seizure medicines. Hazardous sedation, drowsiness, or dizziness may occur if Dayhist-D is used along with any of these drugs.

Talk to your pharmacist and doctor before using any over-the-counter or prescription medicines, including herbal products along with Dayhist-D.

Life Style and Food Habits You Must Follow When on Dayhist-D:

Use Dayhist-D exactly as recommended by your health care provider. Avoid using smaller or larger amounts or for more than prescribed period. You should follow the important instructions given on the prescription label.

Be careful during operating machinery, or performing other risky activities. Dayhist-D may lead to drowsiness or dizziness. If you face these conditions avoid these activities while taking Dayhist-D. Drink alcohol cautiously because it may increase dizziness and drowsiness while taking Dayhist-D.

Always use recommended dose of this medicine. In case your symptoms do not get better, or they become worsen, consult your medical practitioner immediately. 

How safe is Dayhist-D for Pregnant Women or Nursing mothers?

Dayhist might cause harm to your unborn child. Inform your medical expert if you are planning to become pregnant or already pregnant while using this medicine.

Clemastine has been assigned to pregnancy category B by the U.S. FDA and phenylpropanolamine has not been formally assigned to any pregnancy category. There are no controlled data in human pregnancy for either of these. Clemastine-phenylpropanolamine is only recommended for use during pregnancy when its benefits outweigh risks.

Dayhist-D is found in breast milk. This medication can harm your infant. Do not use this medication if you are pregnant or if you face any unusual symptoms. Do not use this medicine without consulting your health care provider if you are a breast-feeding mother.

Complications and Conditions Possible Due to Prolonged Use of Dayhist-D:

Prolonged use of Dayhist-D might lead to numerous side effects which can be harmful to your body. Avoid taking any medication for more than the recommended duration. Prolonged use of any drug is harmful for  body.  Often unwanted side effects of prolonged use can be fatal.

Use this medication as recommended by your medical healthcare professional or as directed on label of medication box. Prolonged use of any drug can make your body reliant on it. In most cases extended use of medicines is injurious to health. So try to avoid using Dayhist-D for a longer period of time.

Better to consult your doctor & discuss everything about extended use of Dayhist-D in case you want to use it for a longer period of time.

Availability of Dayhist-D:

You can easily get Dayhist-D from any drug store. It is available only on prescription