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dolutegravir/lamivudine vs phenytoin

Side-by-side comparison of dolutegravir/lamivudine and phenytoin. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.

moderate Known Drug Interaction

Anticonvulsants: Oxcarbazepine Phenytoin Phenobarbital ↓Dolutegravir Avoid coadministration with DOVATO because there are insufficient data to make dosing recommendations.

Recommendation: Avoid using these drugs at the same time since there are no clear instructions on how to adjust the dosage safely.

Drug Class
dolutegravir/lamivudine Integrase Inhibitor / NRTI Combination
phenytoin Anticonvulsant (Hydantoin)
Type
dolutegravir/lamivudine Prescription
phenytoin Prescription
Summary
dolutegravir/lamivudine

Dovato is a complete HIV-1 treatment that combines two medicines into one tablet. It is used for adults and adolescents who weigh at least 55 pounds.

phenytoin

Phenytoin injection is used to treat certain types of seizures. It can also prevent seizures during or after neurosurgery.

What It Treats
dolutegravir/lamivudine

Dovato is used to treat HIV-1 infection in adults and adolescents (12 years and older, weighing at least 55 pounds). It can be used if you have never taken HIV-1 medicines before. It can also be used to replace your current HIV-1 medicines if your virus is under control (HIV-1 RNA less than 50 copies/mL) and you have not had treatment failure or resistance to the medicines in Dovato.

phenytoin

This medicine treats generalized tonic-clonic status epilepticus, a type of prolonged seizure. It also helps prevent and treat seizures that may happen during or after brain surgery. Sometimes, it can be used for a short time instead of the oral form of phenytoin when you cannot take the medicine by mouth.

How It Works
dolutegravir/lamivudine

Dovato contains two drugs: dolutegravir and lamivudine. Dolutegravir blocks HIV-1 integrase, an enzyme the virus needs to multiply. Lamivudine blocks reverse transcriptase, another enzyme HIV-1 needs to make copies of itself.

phenytoin

Phenytoin works by slowing down the signals in the brain that cause seizures. It stabilizes nerve cell membranes, reducing excessive electrical activity. This helps to prevent seizures from starting or spreading.

Common Side Effects
dolutegravir/lamivudine
  • Headache
  • Nausea
  • Diarrhea
  • Trouble sleeping (insomnia)
  • Tiredness (fatigue)
phenytoin

No common side effects listed.

FAERS Reports
dolutegravir/lamivudine
  • Pain 1,425
  • Anxiety 1,051
  • Emotional Distress 1,048
  • Anhedonia 942
  • Chronic Kidney Disease 701
phenytoin
  • The medicine is reacting with another medicine 1,547
  • Seizure 1,382
  • Poisoning from different substances 1,353
  • Convulsion 1,260
  • Prolonged seizure 790
Serious Warnings
dolutegravir/lamivudine

If you have both HIV-1 and hepatitis B, you should be tested for hepatitis B before starting Dovato. Using Dovato can cause the hepatitis B virus to become resistant to lamivudine. Stopping Dovato can also cause a severe worsening of hepatitis B. Your liver function should be checked regularly.

phenytoin

This medicine can cause serious heart problems if given too quickly. The injection rate should not be faster than 50 mg per minute for adults, and 1 to 3 mg/kg/min (or 50 mg per minute, whichever is slower) for children. Your heart will be monitored closely during and after the injection.

Pregnancy
dolutegravir/lamivudine

There is a pregnancy registry to monitor outcomes in people exposed to Dovato during pregnancy. Talk to your doctor if you are pregnant or plan to become pregnant. There may be a risk of neural tube defects if dolutegravir is taken at the time of conception.

phenytoin

Taking phenytoin during pregnancy may increase the risk of birth defects. If you are pregnant or plan to become pregnant, talk to your doctor about the risks and benefits of this medicine.

Also Compare, Nearby Drugs

How to Read This dolutegravir/lamivudine vs phenytoin Comparison

dolutegravir/lamivudine is classified in the Integrase Inhibitor / NRTI Combination drug class, while phenytoin sits within the Anticonvulsant (Hydantoin) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.

Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, dolutegravir/lamivudine has 5,167 submissions while phenytoin has 6,332. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known moderate interaction flagged in FDA labeling, attributed to phenytoin causes your body to clear dolutegravir more quickly, which reduces the amount of medicine available to fight the virus.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.

A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between dolutegravir/lamivudine and phenytoin - always consult your physician or pharmacist first.

Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.