How diphenhydramine works

The Diphenhydramine is used to combat irritations, redness and itchy eyes, watery eyes, sneezing and runny nose caused by allergies or colds . In addition, it is used against cough caused by minor irritation to the throat and respiratory tract.

Its possible uses include the prevention and treatment of car sickness, insomnia, tremors associated with the early stages of Parkinson’s disease or movement problems that appear as a side effect of taking a drug.

How diphenhydramine works

Diphenhydramine is an antihistamine drug : it works by blocking the activity of histamine, the molecule responsible for the appearance of allergy symptoms.

How diphenhydramine is administered

Diphenhydramine is usually taken as needed , but in some cases the doctor may prescribe regular intake. Possible pharmaceutical forms include tablets (also soluble in the mouth), capsules, powders and solutions. Sometimes it is marketed in combination with other drugs (pain relievers, antipyretics or decongestants).

In general, to relieve the symptoms of an allergy, it is recommended to take Diphenhydramine every 4-6 hours , while against car sickness it is sufficient to take it 30 minutes before the trip, possibly taking it even before meals and before going to sleep. Against insomnia, however, it must be taken 30 minutes before bedtime. Finally, in general, the treatment of uncontrollable movements requires four administrations throughout the day.

Side effects of Diphenhydramine

Its possible side effects also include:

  • dry mouth, nose and throat;
  • drowsiness;
  • dizziness ;
  • nausea ;
  • He retched;
  • loss of appetite;
  • constipation;
  • increased chest congestion;
  • headaches ;
  • muscle weakness;
  • excitement (especially in children);
  • nervousness.

It is important to contact a doctor immediately if the treatment is associated with:

  • vision problems;
  • difficult or painful urination.

Contraindications and warnings on the use of Diphenhydramine

The Diphenhydramine can cause drowsiness which can be dangerous when you are driving and when you operate hazardous machinery. Alcohol can aggravate this side effect.

Diphenhydramine-containing products used to treat coughs and colds should not be administered under 4 years of age. Up to 11 years it is also necessary to use them with caution.

Diphenhydramine drugs may also be contraindicated in the case of phenylketonuria.

Before taking Diphenhydramine it is important to tell your doctor:

  • of any allergies to the active substance, its excipients or any other drug;
  • of medicines, homeopathic medicines and supplements taken , in particular products containing diphenhydramine, other medicines for colds or allergies, medications for anxiety, depression or seizures, muscle relaxants, narcotics, sedatives, sleeping pills and tranquilizers;
  • if you suffer (or have suffered) from asthma, emphysema, chronic bronchitis, other lung diseases, glaucoma , ulcers, difficulty in urination associated with prostate hypertrophy, heart disease, high blood pressure , convulsions, phenylketonuria or hyperthyroidism ;
  • if you must follow a low sodium diet;
  • if you are pregnant or breastfeeding .

It is also necessary to inform surgeons and dentists about taking diphenhydramine.

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