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NRTI backbone (HIV / PrEP) Pregnancy: §4.6 VERBATIM: 'Pregnancy: There are no adequate and well-controlled studies of Emtricitabine/Tenofovir Alafenamide Gilead or its components in pregnant women. There are no or limited data (less than 300 pregnancy outcomes) from the use of tenofovir alafenamide in pregnant women. However, a large amount of data on pregnant women (more than 1,000 exposed outcomes) indicate no malformative nor foetal/neonatal toxicity associated with emtricitabine. Animal studies do not indicate direct or indirect harmful effects of emtricitabine with respect to fertility parameters, pregnancy, foetal development, parturition or postnatal development. Studies of tenofovir alafenamide in animals have shown no evidence of harmful effects on fertility parameters, pregnancy, or foetal development (see section 5.3). Emtricitabine/Tenofovir Alafenamide Gilead should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus. Breast-feeding: It is not known whether tenofovir alafenamide is excreted in human milk. Emtricitabine is excreted in human milk. In animal studies it has been shown that tenofovir is excreted in milk. There is insufficient information on the effects of emtricitabine and tenofovir in newborns/infants. Therefore, Emtricitabine/Tenofovir Alafenamide Gilead should not be used during breast-feeding. In order to avoid transmission of HIV to the infant it is recommended that women living with HIV do not breast-feed their infants. Fertility: There are no data on fertility from the use of Emtricitabine/Tenofovir Alafenamide Gilead in humans. In animal studies there were no effects of emtricitabine and tenofovir alafenamide on mating or fertility parameters (see section 5.3).' §4.4 adds, on mitochondrial dysfunction after in-utero exposure to nucleos(t)ide analogues: 'There have been reports of mitochondrial dysfunction in HIV negative infants exposed in utero and/or postnatally to nucleoside analogues; these have predominantly concerned treatment with regimens containing zidovudine. The main adverse reactions reported are haematological disorders (anaemia, neutropenia) and metabolic disorders (hyperlactatemia, hyperlipasemia). These events have often been transitory. Late onset neurological disorders have been reported rarely (hypertonia, convulsion, abnormal behaviour).'

Emtricitabine with tenofovir alafenamide

Brand names: Descovy

A once-daily fixed-dose combination of the nucleos(t)ide reverse transcriptase inhibitors emtricitabine and tenofovir alafenamide, used as a backbone of HIV-1 treatment with other antiretrovirals and, in eligible adults, for pre-exposure prophylaxis.

Adult dose

Dose: Emtricitabine 200 mg with tenofovir alafenamide 10 mg once daily, OR emtricitabine 200 mg with tenofovir alafenamide 25 mg once daily — the strength depends on the third agent in the regimen. §4.2 Table 1 verbatim: '200/10 mg once daily' with 'Atazanavir with ritonavir or cobicistat / Darunavir with ritonavir or cobicistat / Lopinavir with ritonavir'; '200/25 mg once daily' with 'Dolutegravir, efavirenz, maraviroc, nevirapine, rilpivirine, raltegravir'. Both components are quantified by the SPC (emtricitabine 200 mg; tenofovir alafenamide 10 mg or 25 mg).
Route: Oral. §4.2 verbatim: 'Oral use. Emtricitabine/Tenofovir Alafenamide Gilead should be taken once daily with or without food (see section 5.2). It is recommended that the film-coated tablet is not chewed or crushed due to the bitter taste. For patients who are unable to swallow the tablet whole, the tablet may be split in half and both halves taken one after the other, ensuring that the full dose is taken immediately.'
Frequency: Once daily. §4.2 verbatim: 'Therapy should be initiated by a physician experienced in the management of HIV infection.'
SCOPE — this is the page's PRIMARY indication and route: the NRTI backbone of an oral HIV-1 treatment regimen, which is exactly what §4.2 Table 1 doses, and it quantifies both components of the fixed combination. ⚠️ PrEP IS NOT DOSED ANYWHERE IN THIS BUNDLE. Pre-exposure prophylaxis is not mentioned once in any retrieved section, so no PrEP regimen has been published here. || ⚠️ THE STRENGTH IS CHOSEN BY THE THIRD AGENT, NOT BY THE PATIENT. §4.2 verbatim: 'Emtricitabine/Tenofovir Alafenamide Gilead should be administered as shown in Table 1. Table 1: Dose of Emtricitabine/Tenofovir Alafenamide Gilead according to third agent in the HIV treatment regimen'. The boosted-protease-inhibitor row takes 200/10 mg; the dolutegravir / efavirenz / maraviroc / nevirapine / rilpivirine / raltegravir row takes 200/25 mg. Table 1 footnote 1 verbatim: 'Emtricitabine/Tenofovir Alafenamide Gilead 200/10 mg in combination with darunavir 800 mg and cobicistat 150 mg, administered as a fixed-dose combination tablet, was studied in treatment-naive subjects, see section 5.1.' The product whose SPC was fetched is the 200 mg/10 mg tablet; the 200/25 mg tablet named in Table 1 is a separate presentation whose own SPC was not fetched, although Table 1 states its dose. || MAX DOSE DELIBERATELY LEFT EMPTY — §4.2 states no maximum dose for this or any other regimen; the only ceilings in the section are eligibility thresholds (age ≥ 12 years, weight ≥ 35 kg, CrCl ≥ 30 mL/min), which are not dose caps. || MISSED DOSE / VOMITING, §4.2 verbatim: 'If the patient misses a dose of Emtricitabine/Tenofovir Alafenamide Gilead within 18 hours of the time it is usually taken, the patient should take Emtricitabine/Tenofovir Alafenamide Gilead as soon as possible and resume the normal dosing schedule. If a patient misses a dose of Emtricitabine/Tenofovir Alafenamide Gilead by more than 18 hours, the patient should not take the missed dose and simply resume the usual dosing schedule. If the patient vomits within 1 hour of taking Emtricitabine/Tenofovir Alafenamide Gilead another tablet should be taken.' || ELDERLY, §4.2 verbatim: 'No dose adjustment of Emtricitabine/Tenofovir Alafenamide Gilead is required in elderly patients (see sections 5.1 and 5.2).' || ⚠️ §4.4 and §4.8 are truncated at the source-fetch limit — the warnings and adverse-reaction lists below are not complete, and no interaction section (§4.5) or overdose section was retrieved, so the page's interaction list (rifampicin/rifabutin, anticonvulsant inducers, St John's wort) is NOT sourced from this bundle.

Paediatric dose

Route: Oral
Frequency: Once daily
NOT A WEIGHT-CALCULATED DOSE — this is a fixed-dose combination tablet, so dosePerKg is deliberately null and no mg/kg figure exists anywhere in the SPC. Adolescents who meet the age and weight thresholds take the same adult tablet once daily: §4.2 (renal paragraph) verbatim refers to 'adults or adolescents (aged at least 12 years and of at least 35 kg body weight)'. Below those thresholds there is no dose: §4.2 verbatim, 'Paediatric population: The safety and efficacy of Emtricitabine/Tenofovir Alafenamide Gilead in children younger than 12 years of age, or weighing < 35 kg, have not yet been established. No data are available.' §4.2 also states: 'No data are available to make dose recommendations in children less than 18 years with end stage renal disease.' Which of the two Table 1 strengths applies to an eligible adolescent is decided by the third agent, exactly as in adults. Paediatric prescribing must be verified against a children's formulary and specialist HIV advice.

Dose adjustments

Renal

§4.2 verbatim: 'No dose adjustment of Emtricitabine/Tenofovir Alafenamide Gilead is required in adults or adolescents (aged at least 12 years and of at least 35 kg body weight) with estimated creatinine clearance (CrCl) ≥ 30 mL/min. Emtricitabine/Tenofovir Alafenamide Gilead should be discontinued in patients with estimated CrCl that declines below 30 mL/min during treatment (see section 5.2). No dose adjustment of Emtricitabine/Tenofovir Alafenamide Gilead is required in adults with end stage renal disease (estimated CrCl < 15 mL/min) on chronic haemodialysis; however, Emtricitabine/Tenofovir Alafenamide Gilead should generally be avoided but may be used in these patients if the potential benefits are considered to outweigh the potential risks (see sections 4.4 and 5.2). On days of haemodialysis, Emtricitabine/Tenofovir Alafenamide Gilead should be administered after completion of haemodialysis treatment. Emtricitabine/Tenofovir Alafenamide Gilead should be avoided in patients with estimated CrCl ≥ 15 mL/min and < 30 mL/min, or < 15 mL/min who are not on chronic haemodialysis, as the safety of Emtricitabine/Tenofovir Alafenamide Gilead has not been established in these populations. No data are available to make dose recommendations in children less than 18 years with end stage renal disease.' Note that the adjustment is stop-or-continue, not a reduced dose — no lower mg strength is offered for renal impairment.

Hepatic

§4.2 verbatim: 'No dose adjustment of Emtricitabine/Tenofovir Alafenamide Gilead is required in patients with hepatic impairment.' §4.4 adds two caveats that are not dose changes: 'The safety and efficacy of Emtricitabine/Tenofovir Alafenamide Gilead in patients with significant underlying liver disorders have not been established (see sections 4.2 and 5.2). Patients with pre-existing liver dysfunction, including chronic active hepatitis, have an increased frequency of liver function abnormalities during combination antiretroviral therapy (CART) and should be monitored according to standard practice. If there is evidence of worsening liver disease in such patients, interruption or discontinuation of treatment must be considered.'

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • §4.3 verbatim, and the only contraindication stated: 'Hypersensitivity to the active substances or to any of the excipients listed in section 6.1.'
  • Not a §4.3 contraindication but a §4.2 restriction: children younger than 12 years of age, or weighing < 35 kg — 'The safety and efficacy ... have not yet been established. No data are available.'
  • Not a §4.3 contraindication but a §4.2 restriction: estimated CrCl ≥ 15 mL/min and < 30 mL/min, or < 15 mL/min and not on chronic haemodialysis — 'should be avoided ... as the safety ... has not been established in these populations'; treatment 'should be discontinued in patients with estimated CrCl that declines below 30 mL/min during treatment'.
  • Not a §4.3 contraindication but a §4.6 restriction: breast-feeding — 'Emtricitabine/Tenofovir Alafenamide Gilead should not be used during breast-feeding. In order to avoid transmission of HIV to the infant it is recommended that women living with HIV do not breast-feed their infants.'
  • Not a §4.3 contraindication but a §4.4 caution: patients co-infected with HIV-1 and hepatitis C virus — 'The safety and efficacy of Emtricitabine/Tenofovir Alafenamide Gilead in patients co-infected with HIV-1 and hepatitis C virus (HCV) have not been established.'
  • ⚠️ §4.4 is truncated at the source-fetch limit and §4.5 (interactions) was not retrieved at all — this is not the complete set of restrictions.

Side effects

  • §4.8 summary verbatim: 'In clinical studies of treatment-naïve adult patients receiving emtricitabine and tenofovir alafenamide with elvitegravir and cobicistat as the fixed-dose combination tablet elvitegravir 150 mg/cobicistat 150 mg/emtricitabine 200 mg/tenofovir alafenamide (as fumarate) 10 mg (E/C/F/TAF) through 144 weeks, the most frequently reported adverse reactions were diarrhoea (7%), nausea (11%), and headache (6%).'
  • Very common (≥ 1/10), §4.8 Table 3 — gastrointestinal: nausea
  • Common (≥ 1/100 to < 1/10), §4.8 Table 3 — gastrointestinal: diarrhoea, vomiting, abdominal pain, flatulence
  • Common, §4.8 Table 3 — nervous system and psychiatric: headache, dizziness, abnormal dreams
  • Common, §4.8 Table 3 — skin and general: rash; fatigue
  • Uncommon (≥ 1/1,000 to < 1/100), §4.8 Table 3: anaemia; dyspepsia; angioedema, pruritus, urticaria; arthralgia. The SPC footnotes that angioedema, anaemia and urticaria were identified from post-marketing surveillance or from emtricitabine studies rather than from the F/TAF studies themselves.
  • Immune reactivation syndrome, §4.8 verbatim: 'In HIV infected patients with severe immune deficiency at the time of initiation of CART, an inflammatory reaction to asymptomatic or residual opportunistic infections may arise. Autoimmune disorders (such as Graves' disease and autoimmune hepatitis) have also been reported; however, the reported time to onset is more variable, and these events can occur many months after initiation of treatment (see section 4.4).'
  • Osteonecrosis, §4.8: 'Cases of osteonecrosis have been reported, particularly in patients with generally acknowledged risk factors, advanced HIV disease or long-term' — the sentence is cut off by the source-fetch limit at this point.
  • Severe acute exacerbation of hepatitis on stopping, §4.4 verbatim: 'Tenofovir alafenamide is active against hepatitis B virus (HBV). Discontinuation of Emtricitabine/Tenofovir Alafenamide Gilead therapy in patients co-infected with HIV and HBV may be associated with severe acute exacerbations of hepatitis.'
  • Weight and metabolic changes, §4.4 verbatim: 'An increase in weight and in levels of blood lipids and glucose may occur during antiretroviral therapy.'
  • ⚠️ §4.8 is truncated at the source-fetch limit part-way through 'Description of selected adverse reactions' — this is not the complete list.

Monitoring

  • Renal function on treatment — §4.2 requires that the drug 'should be discontinued in patients with estimated CrCl that declines below 30 mL/min during treatment', which presupposes ongoing CrCl measurement.
  • Liver function in pre-existing liver dysfunction — §4.4 verbatim: 'Patients with pre-existing liver dysfunction, including chronic active hepatitis, have an increased frequency of liver function abnormalities during combination antiretroviral therapy (CART) and should be monitored according to standard practice. If there is evidence of worsening liver disease in such patients, interruption or discontinuation of treatment must be considered.'
  • After stopping in HIV/HBV co-infection — §4.4 verbatim: 'Patients co-infected with HIV and HBV who discontinue Emtricitabine/Tenofovir Alafenamide Gilead should be closely monitored with both clinical and laboratory follow-up for at least several months after stopping treatment.'
  • Blood lipids and glucose — §4.4 verbatim: 'For monitoring of blood lipids and glucose reference is made to established HIV treatment guidelines. Lipid disorders should be managed as clinically appropriate.'
  • Infants exposed in utero — §4.4 verbatim: 'These findings should be considered for any child exposed in utero to nucleos(t)ide analogues, who present with severe clinical findings of unknown aetiology, particularly neurologic findings.'
  • ⚠️ No viral-load or CD4 monitoring schedule appears anywhere in the fetched text; §4.2 only requires that 'Therapy should be initiated by a physician experienced in the management of HIV infection.'

Clinical monograph

How it works

Both components are phosphorylated intracellularly and incorporated into viral DNA by reverse transcriptase, acting as chain terminators; tenofovir alafenamide delivers the active metabolite with lower plasma tenofovir exposure than the disoproxil prodrug.

Prescribing in practice

  • Before use, HIV-negative status must be confirmed in the prophylaxis setting and hepatitis B status checked, as stopping therapy can cause severe hepatitis flares in co-infected patients.
  • Tenofovir alafenamide has a more favourable renal and bone profile than tenofovir disoproxil but still requires caution at low levels of renal function.
  • When used for prophylaxis it is one part of a combined prevention strategy and does not protect against other sexually transmitted infections.

Monitoring

Monitor HIV status, renal function and hepatitis B markers, with periodic testing during ongoing use.

Counselling the patient

  • Take once daily and do not stop suddenly, especially if you have hepatitis B.
  • For prevention, continue regular HIV testing and use condoms to guard against other infections.
  • Attend follow-up appointments for kidney and infection monitoring.

Evidence & guidelines

Tenofovir alafenamide-based combinations are established in HIV treatment and prevention, supported by BHIVA and NICE recommendations.

Reference: BHIVA HIV / PrEP guidelines; EACS; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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