Gelsemium.
Guarana.
Heat: as hot water-bag or poultice to nape of neck.
Hot Sponging.
Hot Water.
Hydrastis: in congestive headache with constipation.
Hyoscyamus.
Ice-bag: applied to head, or leeches back of ears, in severe cases.
Ichthalbin: to improve digestion and nutrition.
Ignatia: in hysterical headache.