21 The frequency of possible side effects listed below is defined using the following system: • very common (affects more than 1 user in 10) • common (affects 1 to 10 users in 100) • uncommon (affects 1 to 10 users in 1,000) • rare (affects 1 to 10 users in 10,000) • very rare (affects less than 1 user in 10,000) • not known (frequency cannot be estimated from the available data)