Table 3. Special considerations in malaria prophylaxis and stand-by emergency treatment'

People with known or suspected allergies or a previous history of adverse reactions

• If history of allergy to sulfa drugs, antimalarials such as sulfadoxine-pyrimethamine and sulfalene-pyrimethamine should not be taken.
• If history of allergy or other severe reaction to mefloquine or related compounds (quinine, quinidine), mefloquine should not be prescribed for prophylaxis.
• If history of severe pruritus after chloroquine treatment, use an alternative drug to chloroquine for prophylaxis.
• Doxycycline may cause skin photosensitivity and should not be prescribed for people likely to be exposed to prolonged direct sunlight. Those who are sensitive should use a highly protective sunscreen and avoid prolonged direct sunlight or switch to another prophylactic drug.

People with chronic illness

• People with chronic illness should seek individual medical advice.
• Chloroquine should not be taken by people with a family history of epilepsy.
• Chloroquine should not be prescribed for people with a history of generalized psoriasis.
• Mef loquine should not be taken by people with a history of epilepsy or psychiatric disorders.

People taking other drugs and vaccines

• Mefloquine and other related compounds (e.g. quinine, quinidine and chloroquine) may be given concomitantly only under close medical supervision because of possible additive cardiac toxicity.
• The co-administration of mefloquine with anti-arrhythmic agents, beta-adrenergic blocking agents, calcium
  channel blockers, antihistamines including H1-blocking agents, tricyclic antidepressants and phenothiazines might contribute to the prolongation of Q-T, intervals. However, in the light of information currently available, co-administration of mefloquine with such drugs is not contraindicated.
• Vaccination with live bacterial vaccines, such as oral live typhoid vaccines, should be completed at least
  3 days before the first prophylactic dose of mefloquine.

People who develop serious side-effects to an antimalarial.

• Stop taking the drug and seek immediate medical attention; this applies in particular to neurological or psychological disturbances after mefloquine and to rashes after treatment with sulfa-derived antimalarials.

People who vomit . 

• Vomiting of antimalarials given for therapy is less likely if fever is first lowered with antipyretics. A second full dose should be given to patients who vomit less than 30 minutes after receiving the drug. if vomiting occurs 30-60 minutes after a dose, an additional half-dose should be given. Vomiting together with diarrhoea may lead to treatment failure due to poor drug absorption.

People involved in tasks requiring fine coordination and spatial discrimination (e.g. air crews)

• Mefloquine prophylaxis should not be given. After mefloquine treatment, caution should be exercised with regard to driving and operating machinery, and piloting aircraft should be avoided, since dizziness, disturbances of balance and neuropsychiatric reactions have been reported during and up to 3 weeks after the use of this drug. Chloroquine may cause blurring of vision and dizziness in some people; those affected should switch to another prophylactic drug.

(*p 81-82 WHO 2001 year book)