Promethazine 12.5 mg 25 mg 50 mg Syrup 6.25 mg per 5 mL Suppositories Injection

What is Promethazine?

Promethazine is a prescription antihistamine in the phenothiazine family used to control nausea and vomiting, prevent motion sickness, ease allergy symptoms like itching or sneezing, and support sleep when symptoms are disruptive. It is available as 12.5 mg, 25 mg, and 50 mg tablets, a syrup that contains 6.25 mg per 5 mL, rectal suppositories, and a clinician administered injection used in monitored settings. Because it can cause sedation, most people reserve doses for times when relief is needed rather than daily long term use unless a clinician advises otherwise.

Many patients compare pharmacies for generic options to keep costs down, and some buy refills online from licensed United States pharmacies that require a valid prescription. Cheap pricing is acceptable when the label clearly lists promethazine, the exact strength, and the product includes a patient information leaflet. Never use any site that ships without a prescription.

Who may benefit

• People with chemotherapy or postoperative nausea when non sedating options are not enough.
• Travelers who need motion sickness prevention and can plan doses around driving or boat duties.
• Adults with nighttime allergy symptoms who tolerate sedating antihistamines.

Children younger than 2 years must not receive promethazine due to life threatening breathing risks. In older children, dosing is strictly guided by a clinician.

How It Works

Promethazine blocks histamine H1 receptors and has anticholinergic activity that dampens signals from the inner ear vestibular system and the chemoreceptor trigger zone that drive nausea and vomiting. By quieting those pathways, the urge to vomit decreases and motion related queasiness is less likely to start. The same antihistamine effect reduces sneezing and itching in allergic reactions.

Sedation results from central H1 blockade and mild anticholinergic effects, which is useful when nausea or itching prevents sleep but requires planning around activities that demand alertness. A minority of users experience lightheadedness from alpha adrenergic blockade, especially with the first doses.

What you may notice day to day

Relief of queasy stomach, fewer sudden waves of nausea during travel, and less itchy nose or eyes at night. Some people feel pleasantly drowsy within an hour, which is why first doses are best tried at home. If dry mouth or blurry vision appear, they usually ease as you learn your best dose and timing.

Dosage Information

Doses are individualized by a clinician based on age, condition, and sensitivity to sedating medicines. Follow your exact label. Do not stack with other sedatives, opioids, or alcohol. Injection is for clinics only because incorrect administration can cause severe tissue injury.

• Nausea and vomiting adults: Common doses are 12.5 mg to 25 mg every 4 to 6 hours as needed. Many plans set a maximum daily total. Start at the lowest dose that controls symptoms.
• Motion sickness prevention adults: 25 mg at bedtime before travel or 25 mg 1 to 2 hours before departure, then every 6 to 8 hours as needed per label. Plan dosing so you are not driving during peak drowsiness.
• Allergy symptoms adults: 25 mg at bedtime, or 12.5 mg to 25 mg up to every 6 hours as directed when daytime sedation is acceptable.
• Syrup 6.25 mg per 5 mL: Use a marked oral syringe or cup. Do not estimate with kitchen spoons.
• Rectal suppositories: Often 25 mg every 4 to 6 hours as directed when vomiting prevents oral dosing. Follow package steps for insertion and hand hygiene.

How to take it

Swallow tablets with water and a light snack if your stomach is sensitive. For syrup, shake the bottle and measure carefully. For suppositories, store in a cool place so they keep shape. If you miss a dose, take it when remembered unless it is close to the next dose. Do not double up.

Buying and adherence tips

If you buy promethazine online, choose a licensed pharmacy that requires a prescription and offers pharmacist counseling. Cheap generic tablets or suppositories are fine when strength, lot, and expiration are clear on the label. Keep a simple log of dose time and symptom relief to fine tune timing with your clinician.

Side Effects

Common effects include drowsiness, dizziness, dry mouth, constipation, blurry vision, and mild headache. These are more noticeable with higher doses or when combined with other sedatives. Standing up slowly, sipping water, and using fiber rich foods can improve comfort. Some people notice photosensitivity and should use basic sun protection.

Less common but important

• Breathing depression: Serious risk in young children and in anyone combining with opioids, alcohol, or benzodiazepines. Seek urgent care for slow or shallow breathing.
• Confusion or agitation: Older adults may be more sensitive and can experience confusion or falls.
• Movement problems: Rare dystonia or restlessness can occur and usually resolves when the medicine is stopped and treated.
• Heart rhythm changes: Rare QT prolongation, especially if you already have heart disease, low potassium or magnesium, or take other QT prolonging drugs. Report palpitations or fainting.
• Injection site injury: Tissue damage can occur with incorrect injection technique. This is why injections belong in supervised settings only.

Stop the medicine and get help right away for trouble breathing, severe confusion, uncontrollable movements, rash with swelling, or chest pain.

Warnings & Interactions

Do not use promethazine in children younger than 2 years. Use extreme caution and the lowest effective dose in older children and older adults. Avoid driving or hazardous tasks until you know your response. People with sleep apnea, chronic lung disease, glaucoma, prostate enlargement with urinary retention, bowel obstruction, seizure disorders, liver disease, or heart rhythm problems need individualized plans.

Drug interactions

• CNS depressants and alcohol: Additive sedation and breathing depression with opioids, benzodiazepines, sleep aids, and alcohol. Do not combine unless a clinician directs a specific plan.
• MAO inhibitors and other anticholinergics: Increased side effects like severe drowsiness, dry mouth, blurry vision, constipation, and confusion.
• QT prolonging medicines: Some antiarrhythmics, macrolide antibiotics, and antipsychotics add risk. Share your full list for review.

Administration cautions

Promethazine injection can cause severe tissue injury with intra arterial injection or extravasation. Clinics prefer deep intramuscular dosing when parenteral use is necessary. Do not attempt to inject at home.

Practical safety tips

Try the first dose at night when you do not need to drive. Store tablets, syrup, and suppositories securely away from children and pets. If you buy refills online, verify pharmacy licensure, the exact strength, and the expiration date. Cheap options are fine when these checks are met. If symptoms persist despite correct use, contact your clinician to adjust the plan rather than increasing the dose on your own.