Histantil (Promethazine) Tablets

Histantil is a prescription medicine containing promethazine, used for allergy symptoms and certain nausea problems. It’s available through BorderFreeHealth and Ships from Canada to US with prescription verification. This overview covers dosing basics, side effects, interactions, and storage, including options for people without insurance.

Promethazine is a first-generation antihistamine (histamine blocker) that can cause drowsiness. Information here is meant to support safe use and better conversations with a clinician or pharmacist. Always follow the directions on the prescription label and the patient leaflet from the dispensing pharmacy.

What Histantil Is and How It Works

Promethazine hydrochloride is an older, sedating antihistamine that blocks H1 receptors involved in allergy symptoms like sneezing, itching, and watery eyes. Because it crosses into the brain, it may also calm nausea and motion-related stomach upset. It has anticholinergic effects (reduces certain nerve signals), which can dry secretions and contribute to sleepiness, blurred vision, or constipation in some people.

Partner pharmacies confirm prescriptions with prescribers before dispensing. Promethazine is also part of the phenothiazine class, which helps explain why it can affect alertness and coordination. In practical terms, people often notice symptom relief alongside sedation, especially when starting therapy or after dose increases. For anyone who needs steady attention for work, school, or caregiving, this tradeoff is important to plan for.

Who It’s For

This medication may be prescribed for allergic conditions and related symptoms, including those found in Allergies, Allergic Rhinitis (hay fever), and Hives (urticaria). It may also be used for nausea and vomiting, motion sickness, or as a sedating adjunct in certain situations when a prescriber decides it is appropriate. For broader context on triggers and treatment approaches, the Allergic Rhinitis Treatment guide can be a helpful reference.

Histantil is not appropriate for everyone. Promethazine is contraindicated in children under 2 years old due to the risk of severe breathing problems. It should also be avoided in people with a known hypersensitivity to promethazine or related phenothiazines. Extra caution is often needed for older adults and for anyone with asthma or chronic lung disease, sleep apnea, glaucoma, prostate enlargement with urinary retention, seizure disorders, or conditions that increase fall risk. Pregnancy and breastfeeding decisions require individualized clinical review.

Dosage and Usage

Dosing depends on the condition being treated, the strength dispensed, and a person’s overall risk profile for sedation and anticholinergic effects. Tablets are typically taken by mouth, and prescribers may direct either scheduled doses or “as needed” use for intermittent symptoms. Alcohol and other sedating drugs can amplify impairment, so clinicians often factor in concurrent therapies when selecting a regimen. Fulfillment is handled through licensed Canadian partner pharmacies.

Because instructions can vary by indication, the table below summarizes common labeling patterns for promethazine tablets for adults; individual prescriptions may differ. Do not change timing or dose without clinical guidance, and do not use someone else’s prescription.

If a dose is missed on a scheduled plan, standard advice is to follow the prescriber’s instructions or the leaflet from the pharmacy. Doubling up can increase side effects and should be avoided unless explicitly directed by a healthcare professional.

Strengths and Forms

Promethazine tablets are commonly available in multiple strengths, including 12.5 mg, 25 mg, and 50 mg. Availability can vary by pharmacy and region, and the dispensed product may be scored to support accurate splitting when a prescriber specifies it. Labels may also list the ingredient as Promethazine HCl, which is the salt form used in many tablet formulations.

This product page focuses on tablets. Promethazine also exists in other dosage forms in some markets (such as liquids, suppositories, or injectable formulations), but those forms have different safety considerations and are not interchangeable without clinical direction. For any substitution request, the safest step is to confirm the intended form, strength, and directions with the prescriber and the dispensing pharmacist.

Storage and Travel Basics

Store tablets at room temperature and protect them from excess heat, moisture, and direct light. Keep the medication in its original container with the pharmacy label intact, and keep it out of reach of children and pets. Bathrooms and kitchen windowsills often have humidity or temperature swings that can shorten shelf-life, so a cool, dry cabinet is usually a better option.

Quick tip: When traveling, keep tablets in carry-on luggage with the labeled container.

For trips or commuting, avoid leaving medication in a parked car where temperatures can rise quickly. If a tablet looks discolored, crumbling, or has an unusual odor, it should be checked with a pharmacist rather than taken. Disposal recommendations vary by area; if take-back programs exist locally, they are often preferred for unused prescription medicines.

Side Effects and Safety

Like many first-generation antihistamines, this treatment can cause drowsiness, dizziness, dry mouth, constipation, and blurred vision. Some people report feeling “foggy” or slower to react, especially when therapy is started or when the dose is increased. Because promethazine can impair coordination, activities that require alertness (driving, operating machinery, ladder work) may be unsafe until individual effects are known.

Why it matters: Sedation can raise fall and accident risk, particularly in older adults.

More serious reactions are uncommon but require urgent evaluation. Seek immediate help for trouble breathing, severe confusion, fainting, severe rash or swelling, uncontrolled muscle movements (extrapyramidal symptoms), or signs of a severe allergic reaction. Contact a clinician promptly for yellowing skin/eyes, dark urine, persistent fast heartbeat, or worsening wheeze. Histantil should not be used in children under 2 years old due to the risk of fatal respiratory depression; pediatric use in older children must be specifically prescribed and monitored.

Drug Interactions and Cautions

Promethazine interacts with many medicines that also cause sedation or slow breathing. Examples include opioids, benzodiazepines, sleep medications, some seizure drugs, and alcohol. Combining therapies can increase dizziness, confusion, and respiratory suppression. Other anticholinergic medicines (for bladder symptoms, Parkinson’s disease, or certain stomach cramps) may add to dry mouth, constipation, or urinary retention.

Histantil can also complicate care in people who have conditions that affect breathing or alertness. Medications that influence heart rhythm, electrolytes, or blood pressure may need added review, especially if there is a history of fainting or arrhythmia. A pharmacist should screen the full medication list, including over-the-counter cold products and other antihistamines. For background on swelling-related allergic reactions that warrant evaluation, see What Is Angioedema.

Compare With Alternatives

Several other allergy medicines may be considered depending on symptoms, desired level of sedation, and comorbid conditions. Second-generation antihistamines such as loratadine are typically less sedating for many people, which can matter for daytime function. First-generation options like diphenhydramine can be sedating as well and may also cause dry mouth or constipation, but product choice depends on the clinical goal and individual risk factors.

For those browsing options, the Claritin Details page and the Diphenhydramine Details page show examples of alternatives in the same broader category. Deeper education can be found in the Claritin Allergy Medicine overview and the Diphenhydramine Xst Guide. Any switch should be reviewed with a clinician, since sedation, medical history, and interacting drugs can change what is safest.

Pricing and Access

Access requires a valid prescription, and the medication is dispensed only after order details are reviewed for appropriateness. Histantil is offered through a referral model that connects patients to partner pharmacies; documentation and identity checks may be required. US shipping from Canada is part of the service structure, but legal requirements still apply for controlled steps like prescription verification.

Cash-pay access is available when insurance isn’t used. For people comparing options, browsing the Allergy Products hub can help organize alternatives by symptom type and formulation. Final costs vary by strength, quantity, and dispensing pharmacy policies, and a pharmacist can clarify whether tablet splitting is appropriate only when explicitly directed on the prescription.

Authoritative Sources

For the most reliable safety details, use official drug references alongside the patient leaflet that comes with the dispensed tablets. These sources summarize contraindications, boxed warnings when applicable, and interaction cautions that may not fit on a short label. They are helpful when preparing questions for a clinician or when checking whether an over-the-counter cold product contains overlapping sedating ingredients.

• NIH medication monograph for promethazine: MedlinePlus Promethazine

Information can differ slightly across countries and manufacturers, so the dispensing pharmacy’s leaflet should be treated as the primary reference for the specific product supplied. If symptoms worsen, new medications are started, or pregnancy status changes, a clinician should reassess whether promethazine remains appropriate and whether monitoring is needed.

To place an order on BorderFreeHealth, submit prescription details for review and select prompt, express shipping at checkout when available.

This content is for informational purposes only and is not a substitute for professional medical advice.