Phenytoin Capsule Side Effects in Pakistan

Complete guide to Phenytoin (Dilantin / Eptoin) side effects. Dose-dependent toxicity, long-term cosmetic effects, and life-threatening serious reactions — all covered with necessary detail.

Compiled by the PakVita Editorial Team · AI-assisted drafting with editorial review · Sourced from DRAP, WHO, BNF · Last updated: 2026-06-17

Side Effects

Quick Answer

Common side effects of Phenytoin include gingival hyperplasia, hirsutism, nystagmus, ataxia (dose-dependent), and sedation. The most serious side effect is Stevens-Johnson Syndrome (SJS) / DRESS — stop the medicine IMMEDIATELY and go to emergency if widespread rash or blistering occurs. Dose-related toxicity can be prevented through serum level monitoring.

Side Effects at a Glance

Common

Nystagmus
Ataxia / unsteadiness
Diplopia (double vision)
Sedation / drowsiness
Gingival hyperplasia
Hirsutism
Acne
Coarsening of facial features

Serious — See a Doctor

Stevens-Johnson Syndrome (SJS) / DRESS — life-threatening rash, blistering, widespread skin reaction — STOP IMMEDIATELY + EMERGENCY
Hepatotoxicity (liver damage — jaundice, elevated LFTs)
Systemic lupus erythematosus-like reaction
Blood dyscrasias — neutropenia, aplastic anaemia (rare)
Cardiac toxicity (IV rapid infusion — hospital setting only)
Growth suppression (children — long-term high doses)

When to See a Doctor Immediately

Widespread rash or skin blistering
Severe ataxia or confusion (phenytoin toxicity — have serum level checked)
Unexpected seizures despite treatment
Jaundice or dark urine (hepatotoxicity)
Swelling or bleeding of the gums (gingival hyperplasia — dentist + doctor)

Phenytoin Capsule Side Effects (Nuksanat)

Phenytoin (Dilantin / Eptoin) has a significant side effect and toxicity profile — this is why serum level monitoring is necessary. Here is the complete guide.

Dose-Dependent Toxicity Signs (Level se Related)

These symptoms occur with serum level — they are early warning signs of toxicity:

Nystagmus — at >20 mg/L
Ataxia — at >30 mg/L
Confusion / drowsiness — increases with level
Diplopia (double vision)

If these symptoms appear, see a doctor immediately and have the serum level checked.

Long-term Cosmetic / Systemic Side Effects (Zaroori Patient Counselling)

These effects occur with regular long-term use — patients must be informed in advance:

Gingival hyperplasia — ~50% of patients; regular oral hygiene essential
Hirsutism — particularly in women; can be distressing
Acne
Coarsening of facial features
Peripheral neuropathy
Osteomalacia / osteoporosis — always take Vitamin D supplements
Megaloblastic anaemia — always take folate supplements

Serious Side Effects (Sanjeedah Nuksanat)

Stevens-Johnson Syndrome (SJS) / DRESS — MOST IMPORTANT

Life-threatening skin reaction
Symptoms: Widespread rash, skin blistering, mucosal involvement (eyes, mouth, genitals)
Action: STOP THE MEDICINE IMMEDIATELY — GO TO EMERGENCY
Delay is dangerous — immediate hospital admission is necessary

Hepatotoxicity

Jaundice, dark urine, elevated liver enzymes — see a doctor

Blood Dyscrasias (Rare)

Neutropenia, aplastic anaemia — long-term monitoring

Systemic Lupus-like Reaction (Rare)

When to See a Doctor (Kab Doctor Se Milna Zaroori Hai)

Widespread rash or skin blistering — STOP IMMEDIATELY + EMERGENCY (SJS/DRESS)
Severe ataxia or confusion — toxicity; have serum level checked
Unexpected seizures — subtherapeutic or paradoxically toxic levels
Jaundice or dark urine — hepatotoxicity
Swelling or bleeding of the gums — dentist + doctor

Side Effects Summary Table

Type	Side Effect	Action
Dose-dependent	Nystagmus, ataxia	Have level checked
Common / Long-term	Gingival hyperplasia	Oral hygiene + dentist
Common / Long-term	Hirsutism, acne	Discuss alternatives with neurologist
Common / Long-term	Osteomalacia	Vitamin D supplement
Serious	SJS / DRESS	STOP IMMEDIATELY + EMERGENCY
Serious	Hepatotoxicity	See a doctor

Reporting Side Effects

If you notice any unexpected side effect, report it on the DRAP pharmacovigilance portal: https://www.dra.gov.pk/pharmacovigilance

The information in this guide is for educational purposes only. If you notice any side effect, contact your doctor or pharmacist.

Frequently Asked Questions

Phenytoin ke masooron ka barhna (gingival hyperplasia) rokne ka koi tarika hai?

Yes — regular and thorough oral hygiene (brushing + flossing) reduces the severity of gingival hyperplasia. Regular dentist visits are also necessary. Professional dental cleaning helps. In severe cases, gingivectomy surgery may be required.

Phenytoin se toxicity ke kya symptoms hain?

Early symptoms of toxicity include nystagmus, ataxia (unsteadiness), and diplopia (double vision). Severe toxicity can cause confusion, seizures (paradoxically), and coma. See a doctor immediately and have the level checked.

SJS aur DRESS kya hain aur phenytoin mein yeh kyun important hai?

Stevens-Johnson Syndrome (SJS) and DRESS are life-threatening skin reactions. Phenytoin can trigger these. If widespread rash, skin blistering, or mucosal involvement occurs, stop the medicine IMMEDIATELY and go to EMERGENCY — delay can be dangerous.

Phenytoin se khawateen mein kya side effects zyada hote hain?

In women, hirsutism, acne, and coarsening of facial features can be particularly distressing. These cosmetic effects occur with long-term use. Discuss alternatives with your neurologist if these side effects cause distress.

Phenytoin se haddiyan kamzor kyun ho sakti hain?

Phenytoin induces the CYP3A4 enzyme, which accelerates vitamin D metabolism — leading to vitamin D deficiency — reduced calcium absorption — and potentially osteomalacia or osteoporosis. Always take vitamin D supplements on your doctor's advice.

Sources

DRAP Registered Products Database — Drug Regulatory Authority of Pakistan
WHO Model List of Essential Medicines, 23rd ed. (2023) — World Health Organization
British National Formulary (BNF) — BMJ Group & Pharmaceutical Press

Medical disclaimer

This page is for educational use only and does not replace professional medical advice. Always confirm diagnosis, dose, and interactions with a qualified doctor or pharmacist before starting or changing any medicine.