Unisom (Diphenhydramine) Dosage and Side Effects
UNISOM belongs to a group of medications known as antihistamines. Antihistamines are used to treat symptoms caused by allergies, including itchy and watery eyes, sneezing, runny nose, and skin irritation. UNISOM also causes drowsiness, and can be used by adults and children 12 years of age and older who occasionally have trouble sleeping (insomnia). The effects of UNISOM can last for up to 6 hours.
Warnings and Precautions
Your doctor may have suggested this medication for conditions other than those listed in this drug information. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
UNISOM should not be taken by anyone who:
- is allergic to UNISOM or to any of the ingredients of the medication
- has an enlarged prostate
- has an obstructed bladder
- has asthma or chronic lung disease
- has certain stomach conditions (e.g., stenosing peptic ulcer or pyloroduodenal obstruction)
- has glaucoma
- has taken an antidepressant medication known as a MAO inhibitor (e.g., phenelzine, tranylcypromine, linezolid)
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Drowsiness/reduced alertness: Avoid driving or operating machinery until you have determined that you do not become drowsy during the day or experience impaired mental or physical abilities while taking this medication. Alcohol, sedatives, and pain medications can increase the side effects (e.g., drowsiness, inability to concentrate) of this medication. Do not undertake any activities that require alertness until you know how this medication affects you.
High blood pressure: People with high blood pressure should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Lung problems: People with lung problems (e.g., asthma, chronic pulmonary disease) should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Medical conditions: For some people, insomnia is caused by other medical conditions. If you have trouble sleeping for longer than 2 weeks, contact your doctor before taking this medication.
Thyroid disease: People with thyroid disease should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: This medication may pass into breast milk. If you are a breast-feeding mother and are taking UNISOM, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: UNISOM is not recommended to be used as a sleep aid for children under 12 years of age.
Seniors: Seniors may experience more side effects with this medication. Talk to your doctor before taking this medication.
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- chest congestion
- dry mouth, nose, and throat
- inability to concentrate
- increased perspiration
- nausea or vomiting
- upset stomach
Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- decreased muscle coordination
- difficulty in passing urine
- excitation (especially in children)
- muscle weakness
- rapid heart rate
- vision problems
Stop taking the medication and seek immediate medical attention if any of the following occur:
- chest tightness
- skin rash or hives
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Interactions with this medication
There may be an interaction between UNISOM and any of the following:
- anticholinergic agents (e.g., atropine, scopolomine)
- barbiturates (e.g., butalbital, phenobarbital)
- benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
- chloral hydrate
- narcotic analgesics (e.g., codeine, morphine, oxycodone)
- neuroleptic medications (e.g., chlorpromazine, haloperidol, loxapine)
- tricyclic antidepressants (e.g., amitriptyline, imipramine, nortriptyline)
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.
Proper Use of this medication
The usual dose for adults and children 12 years of age and older to help with sleep is 25 mg to 50 mg taken by mouth at bedtime. Some people may only need to take 25 mg at bedtime if they are drowsy in the morning (e.g., they find it interferes with their daily activities) after taking the 50 mg dose.
Other related products
The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.