4.7 Effects on ability to drive and use machines
The clinical status of the patient and the adverse event profile of aciclovir should be borne in mind when considering the patients's ability to drive or operate machinery.

As aciclovir administration is occasionally associated with drowsiness and somnolence (usually in patients receiving high doses or with impaired renal function), patients should make sure that they are not affected before driving or using machinery.

There have been no studies to investigate the effect of aciclovir on driving performance or the ability to operate machinery. Further, a detrimental effect on such activities cannot be predicted from the pharmacology of the active substance.

4.8 Undesirable effects
The frequency categories associated with the adverse events below are estimates. For most events, suitable data for estimating incidence were not available. In addition, adverse events may vary in their incidence depending on the indication.

An estimate of the frequency of undesirable effects has been included though this is not certain for all adverse effects. The following convention has been used for the classification of undesirable effects in terms of frequency: very common (>1/10), common (>1/100, <1/10), uncommon (>1/1000, <1/100), rare (>1/10000, <1/1000, very rare (<1/10000).

Blood and the lymphatic system disorders

Very rare: Anaemia, leucopenia and thrombocytopenia.

Immune system disorders

Rare: Anaphylaxis.

Nervous system disorders

Common: Dizziness and headache.

Very rare: Reversible neurological reactions including agitation, tremor, ataxia, dysarthria, psychotic symptoms, encephalopathy, drowsiness, confusional states, hallucinations, somnolence, convulsions, coma and malaise. These effects were usually reported in patients receiving high doses of aciclovir (usually given intravenously), with renal impairment, or with other predisposing factors (see section 4.4). Aciclovir should be used with caution in patients with underlying neurological abnormalities.

Respiratory, thoracic and mediastinal disorders

Rare: Dyspnoea

Gastrointestinal disorders

Common: Nausea, vomiting, diarrhoea and abdominal pain.

Hepato-biliary disorders

Rare: Reversible rises in bilirubin and liver related enzymes.

Very rare: Hepatitis and jaundice.

Skin and sub-cutaneous tissue disorders

Common: Skin rashes, pruritus (including photosensitivity).

Uncommon: Urticaria, accelerated diffuse hair loss .

Accelerated diffuse hair loss has been associated with a wide variety of disease processes and medicines, the relationship of the event to aciclovir therapy is uncertain.Rare: Angioedema, erythema multiforme, Stevens Johnson syndrome, toxic epidermal necrolysis.

Renal and urinary disorders

Rare: Increases in blood urea and creatinine; renal impairment, usually during intravenous therapy, which is usually reversible and responds to hydration and/or dosage reduction but may progress to acute renal failure in patients with predisposing factors.

Very rare: Acute renal failure, renal pain

Renal pain may be associated with renal failure.

General disorders

Common: