Paxista, Molcovir and FabiFlu: the three COVID antivirals compared honestly

Three COVID antivirals sit on our shelf, and they are not three versions of the same thing. One has the kind of trial data that changed hospital admission rates. One is a reasonable second choice with two firm exclusions. One was approved in a hurry in 2020 and has never really caught up with its own marketing. We sell all three, and we’d rather you knew which is which before the parcel is on its way.

Paxista, Molcovir, FabiFlu. Generic Paxlovid, generic Lagevrio, and favipiravir. Here’s the honest comparison — what each does, who each is for, the one rule they all share, and what a course costs. Ten minutes, and you’ll know which name to say to your doctor.

The short answer

Paxista (nirmatrelvir + ritonavir) has the strongest evidence by a wide margin and is the one doctors reach for first in people at risk of severe disease — if your other medicines allow it. Molcovir (molnupiravir) is the alternative when they don’t, with weaker but real evidence, and it’s off the table in pregnancy and under 18. FabiFlu (favipiravir) has the weakest evidence of the three; we’ll say plainly below what the trials found. All three must be started within five days of symptoms. A course is $131.99, $145.99 and roughly $191.99 respectively.

The rule all three share: five days

Every COVID antiviral works the same way at the strategic level: it slows the virus copying itself. That copying peaks in the first few days of illness. After that, symptoms are largely your immune system’s response, and no amount of antiviral changes the course. So the label for all three says start within five days of the first symptom — and in the Paxlovid trial, the benefit was clearest in people who started within three.

Which brings us to the same awkward fact we raise about oseltamivir: tracked delivery is typically 10–18 working days. You cannot test positive on Monday and order a course for that infection. These packs are bought ahead, kept in the cabinet, and used — with a doctor’s go-ahead — when the test line appears. Two more shared rules: finish the course, even if you feel fine on day three; and none of them replaces the vaccine.

Paxista (nirmatrelvir/ritonavir): strongest evidence, most interactions

Paxista is Hetero Healthcare’s generic of Pfizer’s Paxlovid. It’s two drugs in one dose pack: nirmatrelvir, which blocks a viral enzyme (the main protease) that SARS-CoV-2 needs to assemble new copies, and ritonavir, an old HIV drug that does nothing to the virus here but slows the liver’s breakdown of nirmatrelvir so it stays at working levels.

The evidence is what sets it apart. In the pivotal trial of unvaccinated, high-risk adults treated within five days, hospitalisation or death fell by roughly 85–89 per cent against placebo. No other oral COVID antiviral has produced a number like that. In vaccinated, lower-risk people the absolute benefit is smaller, which is why doctors aim it at those most likely to end up in hospital.

The dose

300 mg nirmatrelvir (two 150 mg tablets) + 100 mg ritonavir (one tablet), taken together twice daily for 5 days. That’s three tablets per dose, six a day, 30 tablets in total — which is exactly what a Paxista dose pack contains. With or without food. Don’t stop early. Don’t double up if you miss a dose by more than eight hours; just take the next one.

The catch: interactions

Ritonavir slows the breakdown of a lot more than nirmatrelvir — dozens of common drugs, sometimes to dangerous levels. It’s the main reason doctors choose molnupiravir instead. The list includes:

• → Statins — simvastatin and lovastatin must be stopped; atorvastatin and rosuvastatin usually paused
• → Some blood thinners — rivaroxaban, apixaban, and warfarin dosing all affected
• → Heart-rhythm drugs — amiodarone, flecainide, and others: contraindicated
• → Certain blood-pressure and angina drugs — some calcium-channel blockers, ranolazine
• → Immunosuppressants — tacrolimus, ciclosporin: levels can shoot up
• → Some psychiatric and epilepsy medicines — clozapine, pimozide, carbamazepine, phenytoin
• → Ergot migraine drugs, some sedatives (midazolam, triazolam), and — relevant to our regulars — sildenafil and tadalafil, whose levels rise sharply. Skip the ED tablets for the week.

Kidney function also matters: moderate impairment needs a reduced dose (one nirmatrelvir tablet instead of two), severe impairment rules it out. Side effects are otherwise mild — the famous one is a metallic taste that lasts the five days, plus diarrhoea and nausea. Some people get a “rebound” of symptoms a few days after finishing; it’s usually mild.

Molcovir (molnupiravir): the fallback, with two hard exclusions

Molcovir is Sun Pharma’s generic of Merck’s Lagevrio. It works differently: molnupiravir gets built into the virus’s genetic code as it copies itself and introduces so many errors that the copies can’t function. No ritonavir, so the interaction problem largely disappears — which is exactly why it exists as an option.

The evidence is real but more modest. In its main trial, molnupiravir reduced hospitalisation or death by about 30 per cent in unvaccinated, high-risk adults treated within five days. A later, much larger trial in mostly vaccinated people found it shortened symptoms by a few days but didn’t significantly reduce hospitalisation. So: useful, particularly when Paxista is off the table, but not in the same league.

The dose

800 mg — four 200 mg capsules — twice daily for 5 days. Eight capsules a day, 40 in total. A 40-capsule bottle of Molcovir is one course. With or without food. Finish all five days.

The two exclusions

Because of the way molnupiravir works — inducing errors in genetic copying — there are two groups it is simply not given to:

1. Pregnancy. Not in pregnancy, not when trying to conceive, and with reliable contraception during the course and for four days after (women) or three months after (men, per some guidance). Breastfeeding should pause during the course and for four days after.
2. Under 18. Concern about effects on bone and cartilage growth. Not for children or teenagers, full stop.

Beyond those it’s an easy drug: mild side effects — diarrhoea, nausea, dizziness — and no kidney or liver dose adjustment. Few interactions, few side effects: that’s why it suits older patients on a long medicine list.

FabiFlu (favipiravir): what the evidence actually says

FabiFlu is Glenmark’s brand of favipiravir, a Japanese flu drug repurposed for COVID in 2020. India gave it emergency approval, it was prescribed in enormous quantities during the Delta wave, and it’s still one of the most-searched COVID medicines in South Asia. We stock it because people ask for it. We won’t pretend it’s the equal of the other two.

Here’s the honest position. Favipiravir works in the lab. In people, the trials have mostly been small; some show faster viral clearance on swabs and quicker easing of mild symptoms, but no convincing reduction in hospitalisation or death, and several well-run trials found no meaningful clinical benefit at all. The WHO does not recommend it; US and European regulators never approved it for COVID. A doctor prescribing it for a mild case where nothing else is suitable is defensible. Treating it as a substitute for Paxista in someone at high risk is not.

The dose

It’s a heavy schedule. 1800 mg twice on day one — that’s four and a half 400 mg tablets per dose, nine on the first day — then 800 mg (two tablets) twice daily for up to 14 days in total. A seven-day course is 33 tablets; the full 14 days is 61. Your doctor sets the length. Take it with or without food, and don’t stop at the first sign of improvement.

Cautions

• → Not in pregnancy — favipiravir causes birth defects in animals, and contraception is required during and for a week after the course
• → Raises uric acid — anyone with gout, or on the edge of it, can get a flare
• → Mild rises in liver enzymes, diarrhoea, nausea; rarely, a drop in white cells
• → Not for breastfeeding; caution with kidney or liver disease; interactions with a few drugs including pyrazinamide and theophylline

Side by side

Who should take any of them — and who shouldn’t

For a healthy, vaccinated adult under 50 with a mild case, none of these makes a large difference; the illness passes on its own. The antivirals earn their keep in people at real risk of severe COVID:

• → Age 65 and over — the strongest single risk factor
• → Unvaccinated adults, or those long past their last dose
• → Weakened immunity — cancer treatment, transplant, HIV, long-term steroids or biologics
• → Chronic lung, heart, kidney or liver disease
• → Diabetes, particularly if poorly controlled
• → Obesity
• → Pregnancy — where Paxista may be considered on a doctor’s judgement, and the other two are excluded

The decision tree most doctors use, in plain words: Paxista first, if the interaction list allows it. Molcovir if it doesn’t, and the patient isn’t pregnant or under 18. FabiFlu only where neither is available or suitable, with realistic expectations.

Price per course, from our shelf

A course, not a tablet, is the unit that matters here, so that’s how we’ve done the sums.

On FabiFlu the pack maths is awkward and we’d rather say so than have you find out on day six: the 30-pack doesn’t cover even a seven-day course, so the 60-pack is the realistic minimum. Delivery is free and tracked on every order to our supported countries. Everything arrives in sealed manufacturer packaging, batch and expiry printed, plain outer box, tracked — see the shipping policy and the antiviral range.

Questions we get asked

Which COVID antiviral is the most effective?

Nirmatrelvir/ritonavir (Paxista). In its main trial it cut hospitalisation or death by around 85–89 per cent in high-risk unvaccinated adults treated within five days. Molnupiravir managed about 30 per cent in a similar group. Favipiravir hasn’t shown a convincing reduction in either.

Can I take Paxista with my statin or blood thinner?

Often not without changes. Ritonavir raises the blood levels of many drugs — simvastatin must be stopped, other statins usually paused, and rivaroxaban, apixaban and warfarin all need a doctor’s plan. Some heart-rhythm drugs are outright contraindicated. Have a doctor or pharmacist check your full list before the first dose.

Is Molcovir safe in pregnancy?

No. Molnupiravir works by causing errors in viral genetic copying, and it isn’t given in pregnancy, when trying to conceive, or while breastfeeding. Contraception is needed during the course and for a period after. It’s also not for anyone under 18. Paxista may be considered in pregnancy on a doctor’s judgement.

Does FabiFlu work for COVID?

The honest answer is “not convincingly”. Small trials show faster viral clearance and quicker easing of mild symptoms in some patients, but well-run trials haven’t shown it reduces hospitalisation or death, and the WHO doesn’t recommend it. It’s a last resort where the other two aren’t available or suitable.

What if I start after five days?

The benefit falls away sharply, because viral copying has largely finished and the antiviral has little to act on. Doctors may still treat immunocompromised patients later, but for most people day six is too late. That’s why the pack lives in the cabinet before you’re ill.

What to do now

If you or someone in your household is in a high-risk group, talk to your doctor now — while everyone is well — about which of these they’d want you to have at home, and get the interaction check done in advance. For most people that conversation ends with a Paxista dose pack in the cabinet, or a bottle of Molcovir if their medicine list rules out ritonavir. FabiFlu is there if a doctor specifically wants it; we won’t pretend it’s a match for the others. Whichever it is, order ahead, start within five days of symptoms with a doctor’s go-ahead, and finish the course. Unsure which pack fits your situation? Email us; a person answers, any hour.

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