| Head |
| National Head Injury Foundation Family Hotline | 800-444-6443 |
| National Headache Foundation | 800-843-2256 |
| Health |
| National Health Information Center | 800-336-4797 |
| National Information Systems for Health Related Services | 800-922-9234 |
| Health Practitioner |
| Health Practitioner Helpline | 800-767-6732 |
| American Heart Association | 800-242-8721 |
| Heart Information Service | 800-292-2221 |
| Herpes |
| American Social Health Association | 800-230-6039 |
| Hospice |
| Children's Hospice International | 800-242-4453 |
| Hospice Education Institute Hospicelink | 800-331-1620 |
| National Hospice Organization | 800-658-8898 |
| Hospitality Houses |
| National Association of Hospitality Houses, Inc | 800-542-9730 |
| Huntington's Disease |
| Huntington's Disease Society of America | 800-345-4372 |