Generic Name: Sominex Brand Name(s): Generics only. No brands available.

Uses

What is Sominex® (diphenhydramine) used for?

Sominex® is used to treat sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms.

Sominex® is also used to treat motion sickness, to induce sleep, and to treat certain symptoms of Parkinson’s disease.

Sominex® may also be used for purposes not listed in this medication guide.

How should I take Sominex® (diphenhydramine)?

Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended. Cold or allergy medicine is usually taken only for a short time until your symptoms clear up.

Do not give this medication to a child younger than 2 years old. Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.

You should not use antihistamine medication to make a child sleepy.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

For motion sickness, take diphenhydramine 30 minutes before you will be in a situation that causes you motion sickness (such as a long car ride, airplane or boat travel, amusement park rides, etc). Continue taking diphenhydramine with meals and at bedtime for the rest of the time you will be in a motion-sickness situation.

As a sleep aid, take diphenhydramine within 30 minutes before bedtime.

Call your doctor if your symptoms do not improve after 7 days of treatment, or if you have a fever with a headache, cough, or skin rash.

This medication can affect the results of allergy skin tests. Tell any doctor who treats you that you are using diphenhydramine.

How do I store Sominex® (diphenhydramine)?

Sominex® is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Sominex® in the bathroom or the freezer. There may be different brands of Sominex® that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Sominex® down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Sominex® (diphenhydramine)?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of Sominex® or other medications.
  • You have any other illnesses, disorders, or medical conditions.

Ask a doctor or pharmacist if it is safe for you to take this medicine if you have other medical conditions, especially:

  • Blockage in your digestive tract (stomach or intestines)
  • Bladder obstruction or other urination problems
  • A colostomy or ileostomy
  • Liver or kidney disease
  • Asthma, chronic obstructive pulmonary disease (COPD), or other breathing disorder
  • Cough with mucus, or cough caused by smoking, emphysema, or chronic bronchitis
  • Heart disease, low blood pressure
  • Glaucoma
  • A thyroid disorder
  • If you take potassium (Cytra, Epiklor, K-Lyte, K-Phos, Kaon, Klor-Con, Polycitra, Urocit-K)

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using Sominex® during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Sominex®. Sominex® is pregnancy risk category B, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from Sominex® (diphenhydramine)?

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using diphenhydramine and call your doctor at once if you have:

  • Pounding heartbeats or fluttering in your chest
  • Painful or difficult urination
  • Little or no urinating
  • Confusion, feeling like you might pass out
  • Tightness in your neck or jaw, uncontrollable movements of your tongue

Common side effects may include:

  • Dizziness, drowsiness, loss of coordination
  • Dry mouth, nose, or throat
  • Constipation, upset stomach
  • Dry eyes, blurred vision
  • Day-time drowsiness or “hangover” feeling after night-time use

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with Sominex® (diphenhydramine)?

Sominex® may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Sominex® (diphenhydramine)?

Sominex® may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Sominex® (diphenhydramine)?

Sominex® may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using Sominex® (diphenhydramine).

What is the dose of Sominex® (diphenhydramine) for an adult?

Usual Adult Dose for Extrapyramidal Reaction

Oral: 25 to 50 mg orally 3 to 4 times a day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required

Maximum dose: 400 mg/day

Usual Adult Dose for Insomnia

Diphenhydramine Citrate: 76 mg orally once a day at bedtime

Diphenhydramine Hydrochloride: 50 mg orally once a day at bedtime

Usual Adult Dose for Motion Sickness

Oral:

Prescription formulations: 25 to 50 mg orally 3 to 4 times a day, with the first dose given 30 minutes before exposure to motion and repeated before meals and upon retiring throughout the duration of the journey.

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required. Maximum dose: 400 mg/day

Usual Adult Dose for Allergic Rhinitis

Oral:

Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed. Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed. Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required. Maximum dose: 400 mg/day

Usual Adult Dose for Cold Symptoms

Oral:

Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed. Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed. Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required. Maximum dose: 400 mg/day

Usual Adult Dose for Pruritus

Oral:

Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed. Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed. Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required. Maximum dose: 400 mg/day

Usual Adult Dose for Urticaria

Oral:

Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed. Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed. Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required. Maximum dose: 400 mg/day

What is the dose of Sominex® (diphenhydramine) for a child?

Usual Pediatric Dose for Allergic Rhinitis

Prescription formulations:

1 month and older:

  • Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used. Maximum dose: 300 mg/day
  • Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day. Maximum dose: 300 mg/day

Oral Over-the-Counter (OTC) formulations:

Diphenhydramine Citrate:

  • 6 to 12 years: 19 to 38 mg orally every 4 to 6 hours as needed. Maximum dose: 228 mg/day
  • 12 years and older: 38 to 76 mg orally every 4 to 6 hours as needed. Maximum dose: 456 mg/day
  • Diphenhydramine Hydrochloride:
  • 2 to 6 years: 6.25 mg orally every 4 to 6 hours as needed. Maximum dose: 37.5 mg/day
  • 6 to 12 years: 12.5 to 25 mg orally every 4 to 6 hours as needed. Maximum dose: 150 mg/day
  • 12 years and older: 25 to 50 mg orally every 4 to 6 hours as needed. Maximum dose: 300 mg/day

Usual Pediatric Dose for Cold Symptoms

Prescription formulations:

1 month and older:

  • Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used. Maximum dose: 300 mg/day
  • Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day. Maximum dose: 300 mg/day

Oral Over-the-Counter (OTC) formulations:

Diphenhydramine Citrate:

  • 6 to 12 years: 19 to 38 mg orally every 4 to 6 hours as needed. Maximum dose: 228 mg/day
  • 12 years and older: 38 to 76 mg orally every 4 to 6 hours as needed. Maximum dose: 456 mg/day
  • Diphenhydramine Hydrochloride:
  • 2 to 6 years: 6.25 mg orally every 4 to 6 hours as needed. Maximum dose: 37.5 mg/day
  • 6 to 12 years: 12.5 to 25 mg orally every 4 to 6 hours as needed. Maximum dose: 150 mg/day
  • 12 years and older: 25 to 50 mg orally every 4 to 6 hours as needed. Maximum dose: 300 mg/day

Usual Pediatric Dose for Motion Sickness

Prescription formulations:

1 month and older:

  • Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used. Maximum dose: 300 mg/day
  • Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day. Maximum dose: 300 mg/day

Oral Over-the-Counter (OTC) formulations:

Diphenhydramine Citrate:

  • 6 to 12 years: 19 to 38 mg orally every 4 to 6 hours as needed. Maximum dose: 228 mg/day
  • 12 years and older: 38 to 76 mg orally every 4 to 6 hours as needed. Maximum dose: 456 mg/day
  • Diphenhydramine Hydrochloride:
  • 2 to 6 years: 6.25 mg orally every 4 to 6 hours as needed. Maximum dose: 37.5 mg/day
  • 6 to 12 years: 12.5 to 25 mg orally every 4 to 6 hours as needed. Maximum dose: 150 mg/day
  • 12 years and older: 25 to 50 mg orally every 4 to 6 hours as needed. Maximum dose: 300 mg/day

Usual Pediatric Dose for Insomnia

12 years and older:

Diphenhydramine citrate: 76 mg orally once a day at bedtime

Diphenhydramine hydrochloride: 50 mg orally once a day at bedtime

Usual Pediatric Dose for Extrapyramidal Reaction

1 month and older:

Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used. Maximum dose: 300 mg/day

Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day. Maximum dose: 300 mg/day

Usual Pediatric Dose for Allergic Reaction

1 month and older:

Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used. Maximum dose: 300 mg/day

Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day. Maximum dose: 300 mg/day

How is Sominex® (diphenhydramine) available?

Sominex® is available in the following dosage forms and strengths:

  • Injection solution
  • Tablet
  • Liquid
  • Powder

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Sominex®, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: September 10, 2017 | Last Modified: September 10, 2017

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